Candidate gene markers for sperm quality and
fertility of boar
C.L.Lin a,S.Ponsuksili a,b,E.Tholen a,
D.G.J.Jennen a,
K.Schellander a,K.Wimmers a,b,?
a Institute of Animal Breeding and Genetics,University of Bonn,D-53115Bonn,Germany
b Research Institute for the Biology of Farm Animals,Molecular Biology Research Division,
Wilhelm-Stahl-Allee2,18196Dummerstorf,Germany
Received1September2004;received in revised form14April2005;accepted10May2005
Available online19October2005
Abstract
Candidate genes gonadotropin releasing hormone receptor(GNRHR),prolactin(PRL),prolactin receptor(PRLR),follicle-stimulating hormone beta(FSHB),luteinizing hormone beta(LHB),fol-listatin(FST),inhibin alpha(INHA),inhibin beta A(INHBA)and inhibin beta B(INHBB)were investigated for their association with sperm quality traits of sperm concentration(SCON),motility (MOT),semen volume per ejaculate(VOL),plasma droplets rate(PDR),abnormal sperm rate(ASR) and fertility traits of non return rate(NRR)and number of piglets born alive(NBA).The experi-mental material included356boars of Pietrain(PI)and Pietrain×Hampshire(PI×HA).Analysis of variance revealed signi?cant association of GNRHR with MOT(P=0.0161),PDR(P=0.0048) and ASR(P=0.0201),INHBA was found to have signi?cant effects on PDR(P=0.0318)and ASR (P=0.0067),INHBB was signi?cant(P=0.0360)for SCON trait.FSHB,FST,INHA,PRL,PRLR and LHB had no signi?cant effects on any trait in this experiment.
?2005Elsevier B.V.All rights reserved.
Keywords:Candidate genes;Sperm quality;Fertility;Boars;Reproduction
?Corresponding author.Tel.:+493820868700;fax:+49380868702.
E-mail address:wimmers@fbn-dummerstorf.de(K.Wimmers).
0378-4320/$–see front matter?2005Elsevier B.V.All rights reserved.
doi:10.1016/j.anireprosci.2005.05.023
350 C.L.Lin et al./Animal Reproduction Science92(2006)349–363
1.Introduction
Fertility is one of the most important economical traits in swine production.Reproductive performance is controlled by the genetic make-up of the dam,boar and offspring,but in general it is largely affected by environment.Implementation of arti?cial insemination(AI) in swine production allowed improvement of selection on the boars for production traits. At the same time,it stresses the meaning of the individual boar reproduction performance and requires consequent evaluation of fertilization potential of a semen sample for AI in boar stations.Malmgren and Larsson(1984)proposed that semen evaluation could be used as an indicator of fertility in boars.Sperm concentration,motility and normal sperm rate have usually been used as criteria for semen quality evaluation(Colenbrander et al.,1993). However,a number of laboratory assays that examine cellular attributes of sperm are still unable to predict the fertility of a semen sample consistently(Braundmeier and Miller, 2001).
Advances in molecular techniques can now be used to increase rate of response to selection.It has been proposed that candidate gene analysis can be used to identify individ-ual genes responsible for traits of economic importance(Linville et al.,2001).Hormone and hormone receptors are presumed to be good candidate genes for the reproductive traits because they modulate limiting steps in many reproductive pathways(Vincent et al., 1998a).Therefore,gonadotropin releasing hormone receptor(GNRHR),prolactin(PRL), prolactin receptor(PRLR),follicle stimulating hormone beta(FSHB),luteinizing hormone beta(LHB),follistatin(FST),inhibin alpha(INHA),inhibin beta A(INHBA)and inhibin beta B(INHBB)genes known for their function in male hormone pathways were chosen to investigate their effects on sperm quality traits and boar fertility.
The hypothalamic gonadotropin-releasing hormone(GNRHR)is a key regulator of the reproductive system,triggering the synthesis and release of LH and FSH in the pituitary. The gonadotropin-releasing hormone receptor(GNRHR)is a guanine nucleotide-binding protein-coupled receptor with a characteristic seven transmembrane domain motif.It trans-duces the hypothalamic message carried by the decapeptide gonadotropin-releasing hor-mone.At the gonadotrope cell surface the hormone binds to the receptor,leading to pituitary synthesis and secretion of gonadotropins(Cohen,2000).GNRHR de?ciencies and GNRHR mutations are associated with idiopathic hypogonadotropic hypogonadism or Kallmann’s syndrome in humans(Layman et al.,1997;Seminara et al.,1998;Tamaya,2002;Bo-Abbas et al.,2003),because GNRHR mutations reduce GNRHR binding and/or activation of inos-itol triphosphate or phospholipase C(Achermann and Jameson,1999).
PRLR mRNA expression is almost consistent with PRL binding sites except for elongated spermatids and spermatozoa suggesting that PRL may have direct effects on spermatogenic cells(Hondo et al.,1995).PRLR?/?knockout mice showed delayed fertility in males; the effects of PRL on testosterone production of Leydig cells and accessory reproduc-tive glands can obviously be?nally compensated by other regulatory factors(Bole-Feysot et al.,1998).Seminal plasma prolactin concentrations in man were related directly to sperm concentrations and motilities(Aiman et al.,1998).
Follicle stimulating hormone(FSH)acts on the germinal cells in the seminiferous tubules of the testis and is responsible for spermatogenesis up to the secondary spermatocyte stage; later androgens from the testis support the?nal stages of spermatogenesis(Hafez and Hafez,
C.L.Lin et al./Animal Reproduction Science92(2006)349–363351 2000).FSH in?uences the sexual behaviour and testicular morphology and function of the boar(Ellendorff et al.,1970;Zanella et al.,1999).FSH is a heterodimer composed of alpha and beta subunits that are coded by two distinct genes.The beta subunit offers speci?city. The expression of FSHB gene in boar is positively associated with activin beta B-subunit (Li et al.,1998).Male homozygous FSHB knockout mice had normal levels of serum testosterone but had small testes and oligospermia(Layman,2000).
Luteinizing hormone(LH)in?uences the sexual behavior and testicular function of the boar(Ellendorff et al.,1970).The interstitial cells(Leydig cells)produce androgens after LH stimulation(Hafez and Hafez,2000).LH is a glycoprotein composed of an alpha and a beta subunit with a molecular weight of30,000Da and a biologic half life of30min.LHB gene expressed during spermatogenesis and male sexual behavior and FSHB may participate in spermatogenesis,whereas LHB is more involved in spermatogenesis(Degani et al.,2003).
A mutation causing inactivation of the LH beta subunit in human leads to absence of Leydig cells,lack of spontaneous puberty and infertility(Huhtaniemi et al.,1999).
Follistatin(FST)is a protein isolated in testis that may modulate a range of testicular actions of activin(Meinhardt et al.,1998).It not only inhibits the secretion of FSH similar to that of inhibins(INHs)but also binds activin(ACN)and neutralies its biological activity, thus it modulates the secretion of FSH.The gonads are the main source of INH and related proteins,which contribute to the endocrine regulation of the reproductive system.Sertoli cells in the male produce INHs.INHs are not steroids but proteins comprising two disul?de bridges subunits called?and?.In male,INHs are secreted via the lymph.By inhibiting FSH release without altering LH release,INHs may partly be responsible for the differential release of LH and FSH from the pituitary.Besides the regulation of pituitary FSH,INHs related proteins regulated Leydig cell function(Risbridger et al.,1996)over expression of inhibin alpha-subunit gene leads to a disruption of the normal INH-to-ACN ratio and to reproductive de?ciencies,therefore INH and ACN act to regulate FSH secretion and are essential for normal gonadal function(Cho et al.,2001).The expression of INHBA and INHBB,FST and ACNA receptor messenger RNA(mRNAs)in different stages of seminiferous epithelial cycle regulated spermatogenesis(Kaipia et al.,1992).Both levels of serum INHB and seminal plasma INHB could re?ect testis spermatogenesis status,levels of seminal plasma INHB could also re?ect the function of seminiferous duct(Hu and Huang, 2002).
The objective of this study was to elucidate effects of polymorphisms of candidate genes on sperm quality traits of sperm concentration(SCON),semen volume per ejaculate(VOL), motility(MOT),plasma droplets rate(PDR),abnormal sperm rate(ASR).In addition,these genes were also tested for association with fertility traits,non return rate(NRR)and number of piglets born alive(NBA),that re?ect the success rate of arti?cial inseminations.
2.Materials and methods
2.1.Animals
In total,356boars of an AI boar station born between1990and1999and used in commercial pig herds mainly of North Western Germany were included in the study.The
352 C.L.Lin et al./Animal Reproduction Science92(2006)349–363
Table1
Means,standard deviation(S.D.),sample size,ranges of traits
Traits Sample size Mean S.D.Minimum Maximum NRR(%)a3560.554 6.217?24.0719.62 NBA(pig/litter)a3560.0120.550?2.97 1.40 SCON(108/ml)49416 2.9870.979 1.0 6.0 VOL(ml)52221250.1968.4441499 MOT(%)4967185.43 3.497592
PDR(%)41591 6.59 2.37115
ASR(%)43011 6.64 2.55318
a Fertility(NRR,NBA)corrected with factors:parity,farm,season and breed.
boar population was composed of the purebred Pietrain(PI)(n=244)and the crossbred Pietrain×Hampshire(PI×HA)(n=112).
2.2.Phenotypes
Sperm quality traits including sperm concentration(SCON[×108/ml]),sperm motility (MOT[%]),semen volume per ejaculate(VOL[ml]),plasma droplets rate(PDR[%]) and abnormal spermatozoa rate(ASR[%])were obtained from each ejaculate with light microscopy according to the guidelines of the World Health Organization.For each boar the repeated measurements of sperm quality traits were available.The semen samples of boars were collected with date and boar age records,as season and boar age are important factors affecting sperm quality traits.Fertility data(non return rate[NRR]and number of piglets born alive[NBA])of each boar was given as the deviation from the population means within breed,parity of sow,farm and season classes.The sperm quality traits and boar fertility traits are in normal distribution and shown in Table1.
2.3.Molecular tests
Sperm samples of boars were collected from January2000to December2001and stored at?20?C for DNA isolation.Genomic DNA was puri?ed by standard protocol using mercaptoethanol treatment and proteinase K digestion followed by phenol/chloroform extraction and precipitation with isopropanol.
Boars were genotyped for nine candidate gene loci(GNRHR,PRL,PRLR,FSHB,LHB, FST,INHA,INHBA,INHBB).Single nucleotide polymorphisms(SNPs)within GNRHR and LHB gene have been described by Jiang et al.(1999,2001).Primers for GNRHR and LHB were developed from pig sequences(accession no:AF227686and U78106,respectively). Genotyping of these two SNPs was performed by PCR-SSCP.The polymorphism of PRL was described by Vincent et al.(1998b),and primers were designed based on porcine PRL (accession no:X14068).Primer sequences and reaction conditions for FSHB,PRLR and INHA were described by Rohrer et al.(1994),Vincent et al.(1997),and Hiendleder et al. (2002),respectively.The polymorphisms of PRL,PRLR,FSHB and INHA were analyzed by PCR-RFLP.Microsatellite markers in FST,INHBA and INHBB gene were described by Ellegren(1993),Campbell et al.(2001),and Nonneman and Rohrer(2003),respectively.
C.L.Lin et al./Animal Reproduction Science92(2006)349–363353 Length polymorphisms of the repetitive sequences of the porcine FST,INHBA and INHBB gene was determined using a LI-COR DNA sequencer model4200.
2.4.Statistical analysis
Allele frequencies were calculated and genotypes were tested for Hardy–Weinberg equi-librium for these loci using Genepop software version3.3(Raymond and Rousset,1994).
2.4.1.Association analysis for fertility traits
The fertility traits of NRR(%)and number of NBA(per litter)were only available as an average of the mated sows.The statistical?xed model comprised the effects of breed,boar birth year and genotype.This analysis was carried out using model1with the procedure “PROC GLM”of SAS software package(SAS System for Windows,release8.02;SAS Institute,Cary,North Carolina,USA).
y ijkl=μ+breed i+genotype j+year k+εijkl[Model1]
where y ijkl is the boar fertility traits(NRR,NBA),μis model constant,breed i is the?xed effect of the i th breed(i=PI,PI×HA),genotype j is the?xed effect of the j th genotype (j=1–2for GNRHR;j=1–3for PRLR,LHB,FSHB,INHA,j=1–4for PRL;j=1–16,for FST;j=1–5for INHBA,j=1–14for INHBB),year k is the?xed effect of the k th boar-birth-year(k=1–3:boar born before96,in96–97and in98–99),εijkl is residual.For microsatellite marker FST,INHBA and INHBB,alleles were replaced by a pseudo allele999when the allele frequency was less than5%.Therefore,16genotypes of FST,5genotypes of INHBA, and14genotypes of INHBB were used in association analysis.For GNRHR,PRL,FST, INHBA and INHBB not all possible genotypes were found in the boar population,with the total number of genotypes as indicated above.
The additive and dominance effects on fertility traits NRR and NBA were evaluated for FSHB,LHB and INHA gene.Additive effect was estimated by comparison of the means of the traits value for homozygote,i.e.a=1/2(BB?AA).The dominance effect (d)for alleles A and B was calculated from the means for three genotypes as follows: d=AB?1/2(AA+BB).The estimates of effects were tested by t-test on signi?cant devia-tion from zero.
For microsatellite marker FST,INHBA and INHBB,allele substitution effects of the most frequent alleles were evaluated.The following alleles were used in allele substitution effect estimation:?ve alleles142,143,144,147and148of FST;three alleles252,254and256 of INHBA;?ve alleles161,163,171,173and175of INHBB locus.The allele substitution effects show whether the breeding value of fertility traits NBA and NRR change if the frequency of the single allele increases by selective mating.Allele substitution effects were tested by multiple regression analysis with different covariable and it revealed whether the relevant allele positively or negatively in?uence the fertility traits of boars that was homozygote or heterozygote for this allele.The statistical analysis was carried out with the following Model2using the procedure“PROC GLM”of the SAS software package(SAS System for Windows,release8.02).
y ijkl=μ+breed i+b j allele j+year k+εijkl[Model2]
354 C.L.Lin et al./Animal Reproduction Science92(2006)349–363
where y ijkl is the boar fertility traits(NRR,NBA),μis model constant,breed i is?xed effect of the i th breed(i=PI,PI×HA),allele j is the frequency of allele by the ijkl th boar,b j is line regression coef?cient for all allele(j=5for FST,INHBB,j=3for INHBA),year k is ?xed effect of the k th boar-born-year(k=1–3:boar born before96,in96–97,in98–99),εijkl is residual.
2.4.2.Association analysis for sperm quality traits
Analyses of variance were performed with the procedure“PROC MIXED”of the SAS software package(SAS System for Windows,release8.02)to address effects on sperm quality including sperm concentration(SCON[×108/ml]),sperm motility(MOT[%]), semen volume per ejaculate(VOL[ml]),plasma droplets rate(PDR[%])and abnormal spermatozoa rate(ASR[%]).Statistical analyses were carried out using Model3with the ?xed effects of breed,collected season(eight seasons within2years),age(covariable), genotype of boars and random permanent effect of the boar(repeated measurement).
y ijhlm=μ+breed i+age ijhlm+season h+genotype l+animal ijhlm+εijhlm
[Model3]
where y ijhlm is sperm quality traits(SCON,VOL,MOT,PDR,ASR),μis overall population mean,breed i is the?xed effect of the i th breed(i=PI;PI×HA),age ijhlm is?xed effect of boar age(covariable),season h is?xed effect of the h th season(h=1–8),genotype l is?xed effect of the l th genotype(l=1–2for GNRHR;l=1–3for PRLR,LHB,FSHB,INHA;l=1–4 for PRL;l=1–16for FST;l=1–5for INHBA;l=1–14for INHBB),animal ijhlm is permanent environmental effect of the ijhlm th boar(random),εijhlm is residual.
The additive and dominance effect on sperm quality traits was estimated for candidate gene FSHB,INHA and LHB,when these markers were signi?cantly associated with any sperm quality trait(SCON,VOL,MOT;PDR,and ASR).
The allele substitution effect on sperm quality traits was estimated for microsatellite markers FST,INHBA and INHBB,when these markers were signi?cantly associated with any sperm quality trait(SCON,VOL,MOT,PDR and ASR).Allele substitution effect on the sperm quality trait was evaluated using multiple regression analysis with different allele covariable.Statistical analysis was carried out with Model4using the procedure“PROC MIXED”of the SAS software package(SAS System for Windows,release8.02).
y ijhlm=μ+breed i+age ijhlm+season h+d l allele l+animal ijhlm+εijhlm
[Model4]
where y ijhlm is sperm quality traits(SCON,VOL,MOT,PDR,ASR),μis overall population mean,breed i is?xed effect of the i th breed(i=PI;PI×HA),age ijhlm is?xed effect of boar age(covariable),season h is?xed effect of the h-th season(h=1–8),allele l is frequency of the relevant allele by the ijklm th boar,d l is line regression coef?cient for all alleles(l=5for FST,INHBB;l=3for INHBA),animal ijhlm is permanent environmental effect of the ijhlm th boar(random),εijhlm is residual.
Results of calculation with above models are presented as least square means(LSM) and their standard errors(S.E.).Only signi?cant effects were shown in data.Rare geno-
C.L.Lin et al./Animal Reproduction Science92(2006)349–363355 Table2
Frequencies of alleles of GNRHR,PRL,PRLR,LHB,INHA and FSHB within PI and PI×HA
Gene allele GNRHR PRL PRLR LHB INHA FSHB
C G A B C A B C T A B A B PI.93.07.48.09.43.72.28.59.41.11.89.83.17 PI×HA.83.17.59.17.24.90.10.63.37.34.66.82.18
types(frequency less than1%)of microsatellite markers were excluded from the statistical analysis.
3.Results
3.1.Allele frequency
The allele frequencies of markers were calculated within breed as shown in Tables2and3.The chi-square revealed that the locus GNRHR,FSHB,INHA and LHB are in Hardy–Weinberg equilibrium in both PI and PI×HA breeds.The PRLR gene was not in Hardy–Weinberg equilibrium in the PI purebred;the INHA gene was not in Hardy–Weinberg equilibrium in the crossbred;and the PRL gene is not in Hardy–Weinberg equilibrium in either breed.
For microsatellite markers FST,INHBA and INHBB,the allelic frequencies are shown in Table3.For FST locus in both PI and PI×HA breeds and INHBB locus in crossbred PI×HA,there are signi?cant deviation of the observed genotype frequencies from the expected under Hardy–Weinberg equilibrium.In contrast,INHBA in both PI and PI×HA breeds and INHBB in the pure PI breed are in Hardy–Weinberg equilibrium.
Table3
Allele frequencies of FST,INHBA and INHBB within PI and PI×HA
FST INHBA INHBB
Allele PI(n=244)PI×HA
(n=112)Allele PI(n=244)PI×HA
(n=112)
Allele PI(n=244)PI×HA
(n=112)
140bp0.0020248bp0.0060159bp0.0020.125 141bp0.0160.036252bp0.7970.705161bp0.0040.156 142bp0.1090.297254bp0.1450.152163bp0.0430.103 143bp0.2950.290256bp0.0430.098171bp0.5060.451 144bp0.0900.062258bp00.045173bp0.2270.129 145bp0.0350.022262bp0.0080175bp0.2170.036 146bp0.0510.054
147bp0.1600.165
148bp0.2270.080
149bp0.0120.004
356 C.L.Lin et al./Animal Reproduction Science92(2006)349–363
Table4
Least square means for GNRHR genotype effects on sperm quality traits
Genotype MOT(%)PDR(%)ASR(%) CC84.80±0.15y 6.80±0.07a 6.95±0.09x CG85.56±0.28x 6.39±0.13b 6.51±0.17y LSM signi?cantly for genotypes with different superscripts(a,b:P<0.01;x,y:P<0.05).
Table5
Allele substitution effect of INHBA marker on PDR(%)and ASR(%)
Allele PDR(%)ASR(%)
Estimates P-value Estimates P-value 252bp0.06±0.270.82?0.40±0.340.2387 254bp0.19±0.280.490.01±0.350.9686 256bp0.21±0.3100.49?0.24±0.390.5434
3.2.Candidate gene effects
Analysis of variance revealed signi?cant association of GNRHR with MOT(P=0.0161), with PDR(P=0.0048)as well as with ASR(P=0.0201)in the population as shown in Table4.Heterozygote boars for GNRHR had signi?cantly higher sperm motility and were prone to decrease abnormal sperm rate and immature sperm rate when compared to homozy-gote CC.
INHBA gene signi?cantly affected PDR(P=0.0318)and ASR(P=0.0067)in the boar population.The allele substitution effects at INHBA locus on PDR and ASR in the boar populations were estimated with model4as shown in Table5.For PDR trait,allele substi-tution effects were positive but not signi?cant.For ASR trait,allele252bp and allele256 bp tend to have negative effects on ASR trait.Allele254bp tends to have positive effect on ASR trait;anyhow none of the allele substitution effects were signi?cant.
INHBB gene was signi?cantly associated with SCON(P=0.0360)in the boar population. The allele substitution effects on SCON were estimated as shown in Table6.These allele sub-stitution effects were mainly negative and varied from?0.133×108/ml to0.030×108/ml, but no signi?cant allele substitution effect on ASR was observed.
Table6
Allele substitution effect of INHBB locus on SCON(108/ml)
Allele SCON(108/ml)
Estimates P-value 161bp?0.080±0.1570.6095 163bp?0.090±0.1810.6195 171bp?0.073±0.1490.6251 173bp?0.133±0.1520.3799 175bp0.030±0.1600.8492
C.L.Lin et al./Animal Reproduction Science92(2006)349–363357
Candidate gene FST,FSHB,INHA,PRL,PRLR and LHB had no signi?cant effect on
any trait in this experiment.No signi?cant relationship between genotypic variation of all
nine loci and boar fertility traits NRR and NBA were observed.
4.Discussion
Obviously female fertility has a greater impact on the reproductive performance real-
ized in a commercial herd than boar fertility and therefore,more efforts have been made to
elucidate genetic components controlling female fertility.Candidate gene analyses for repro-
ductive traits in female of swine have successfully demonstrated the opportunity to select for
improved reproductive performance,such as a favourable gene ESR reported by Rothschild
et al.,1996.Traits related to fertility of boar are of low heritability(h2≈0.01–0.06;See, 2000)and are strongly affected by environmental and genetic effects of the boar itself,the
dam and the offspring.Therefore,effects of single loci are expected to be low and require a
higher number of animals to be identi?ed.In contrast,sperm quality traits have moderate to
medium heritability(h2≈0.19–0.37;See,2000).In male,more and more candidate gene loci for sperm quality or boar fertility traits have been detected,such as the heat shock pro-tein70.2gene(HSP70.2)(Huang et al.,2002),steroid21-hydroxylase gene(CYP2)(Kmiec et al.,2002),ryanodine receptor gene(RYR1)(Hardge et al.,1995;Urban and Kuciel,2001), prolactin receptor gene(PRLR)and osteopontin gene(OPN)(Steinheuer V on et al.,2002) and retinol-binding protein4gene(RBP4)(Steinheuer V on et al.,2003).On the other hand, the QTL reported for male sexual development were obtained from genital tract measure-ments after either castration or slaughter in Meishan×Large White crosses.The signi?cant associations were detected on seven different chromosomes(SSC1,SSC3,SSC4,SSC7, SSC10,SSC13,and SSCX)(Bidanel et al.,2001;Rohrer et al.,2001).In present study, focus was six candidate genes with single nucleotide polymorphisms,GNRHR,PRL,PRLR, LHB,INHA,FSHB and three candidate genes with microsatellites,FST,INHBA,INHBB. Association with boar fertility was pointed out for GNRHR,INHBA and INHBB.Some loci, PRLR in Pietrain,INHBB in the crossbreeds and PRL,INHA and FST in both populations, show deviation from Hardy–Weinberg equilibrium.This is likely to be due to divergent allele frequencies in the purebred and/or selection.AI boars are highly selected for a num-ber of traits.Thus deviation from Hardy–Weinberg equilibrium is not necessarily due to selection for the traits examined here but also other traits that maybe under control of the genes analyzed or closely linked genes.
GNRHR locus was for the?rst time shown to be signi?cantly associated with MOT,PDR and ASR.In human,GNRHR mutations are signi?cantly associated with male infertility (Layman et al.,1997).The C allele of GNRHR was the most abundant in the purebred PI and the crossbred PI×HA animals while the G allele was the favourable one with regard to the fertility traits.Jiang et al.(2001)reported that frequency of G allele of GNRHR was0.42 in European Large White and0.94in Meishan which is known for its better reproductive performances(Borg et al.,1993).This may indicate there was no selection pressure on GNRHR when recruiting boars for AI.This might be due to the small effect of the locus on fertility and/or effects of GNRHR on other traits.Rohrer et al.(2001)showed that QTL regions affecting the concentration of serum FSH in Meishan×Large white boars on
358 C.L.Lin et al./Animal Reproduction Science92(2006)349–363
different chromosomes,including SSC8(Position19cM).However,GNRHR was assigned to SSC8q1.1–1.2(Rohrer,1999)in far distance from that QTL for FSH serum concentration. QTL for growth traits have been identi?ed in vicinity to GNRHR as well as QTL for other fertility traits like age at puberty,prenatal survival and ovulation rate(Casas-Carrillo et al.,1997;Milan et al.,2002;Cassady et al.,2001;King et al.,2003;Rathje et al.,1997) supporting suggestions raised by our?nding.
A high polymorphic(CA)n repeated sequence exists in porcine INHBA gene as described by Moran(1993).Campbell et al.(2001)reported six alleles and heterozygote0.78in the parents of pig in the USDA-MARC porcine linkage map experiment.In the present study,?ve alleles in PI breed and four alleles in PI×HA boars were observed.The lacking allele/s in both boar populations might result from selection or small population size.The heterozygosities in PI(0.32)and in PI×HA(0.52)were less than that reported by Campbell et al.(2001).The polymorphism of INHBA was signi?cantly associated with PDR and ASR in this study.Kaipia et al.(1992)reported that the expression of inhibin beta A in different stages of seminiferous epithelial cycle regulated spermatogenesis.
Nonneman and Rohrer(2003)reported that a length polymorphisms of the repetitive sequences(AG)n exists within exon2of INHBB gene with six alleles.In the present study, also six alleles were https://www.doczj.com/doc/a811886971.html,paring the allele frequencies within both breeds,showed that the allele171bp had highest frequency in both breeds,but the distributions of other alleles were different within both breeds.The signi?cant association of INHBB locus with SCON trait was observed for the?rst time.Serum inhibin B was suggested as marker for sperm production and infertility in man and monkey(Hu and Huang,2002;Plant and Marshall,2001).
The effects observed here were above the5%signi?cance level for each testing,but did not reach even the10%signi?cance level after correction for multiple testing(P<0.0018;56 tests).Failure to detect more pronounced effects is due to unfavourable allelic distribution–as for GNRHR with the most desired genotype missing in our sample–and low gene effects requiring high animal numbers to be statistically con?rmed.Anyhow there are functional and positional data that support our?ndings.
For the genes PRL,PRLR,FSHB,FST,INHA and LHB no signi?cant effects on any sperm quality traits were observed in PI and PI×HA boar population.
Two polymorphic sites were identi?ed with restriction enzyme BstUI in ampli?ed frag-ments of intron2of the PRL gene.A total of four possible alleles were observed by Vincent et al.(1998b).Three alleles A,B,C and?ve genotypes AA,AB,AC,BC and CC were observed in PI and PI×HA boar populations,the fourth allele,representing the undigested PCR product was not detected in this study.This result was similar to the?ndings in polish 990synthetic pig line reported by Korwin-Kossakowska et al.(2003).Vincent et al.(1998b) reported allele A was most frequent with frequency ranging from0.41to1.0in seven pig breeds of Chester White,Hampshire,Landrace,Large White,Yorkshire and Meishan.This is in agreement with our?nding that allele A was most frequent in the boar populations of PI(0.49)and PI×HA(0.59).QTL regions affecting development of male gonads and accessorial gland(testes weight,epididymis weight and length of bulbo-urethral gland) were identi?ed in Meishan×Large White boars at position66cM,86cM,and143cM of SSC7(Bidanel et al.,2001).The PRL gene maps in this region but is not marked as a positional candidate by our study.
C.L.Lin et al./Animal Reproduction Science92(2006)349–363359
The allele A of PRLR was prevalent in PI and in PI×HA boars,this is similar to ?ndings in the Duroc(79%),Landrace(72%),and Meishan(56%)breed(Vincent et al., 1997).Linville et al.(2001)reported that the frequency of allele B of PRLR gene increased in two lines selected for an index of ovulation rate and embryo survival,and litter size.The effect of selection,different allelic frequencies in the founder animals and random genetic drift could have caused allele frequencies to differ among lines(Linville et al.,2001). Functional evidence for association of PRLR arises from knock out experiments showing delayed fertility in male mice.Steinheuer V on et al.(2003)reported the polymorphism of PRLR locus had signi?cant effect on number of piglets alive in boars of German Landrace breed.
Homozygote AA of FSHB gene was very frequent in both breeds,allele A was more than80%in PI and PI×HA boar population.Korwin-Kossakowska et al.(2003)reported allele A of this reproduction gene FSHB was even more frequent(>90%)in polish990pig synthetic line.The frequency of allele A of FSHB might be enhanced by selection of AI boar for reproduction traits.The functional evidence for association of FSHB arises from knock out experiments showing that de?ciency at FSHB gene decreased sperm concentration75% (Layman,2000).Ford et al.(1997)reported that a negative relationship in mature Meishan boars between FSH secretion and testicular size was accompanied with decreased total daily sperm production.Furthermore,seminal FSH and testosterone concentrations were positively correlated with sperm output in man(Vasquez et al.,1986).
A mononucleotide repeat(A)n of porcine follistatin gene was reported by Moran(1993). Ellegren(1993)found six alleles,heterozygosity0.69at FST locus derived from ten founder animals(two wild boars and eight Large White sows)in the Swedish reference pedigree.In the present study,10alleles,heterozygosity0.49in Pietrain and nine alleles,heterzyogosity 0.47in crossbred PI×HA were https://www.doczj.com/doc/a811886971.html,paring the allele frequencies in both breeds showed that their frequency pro?les were strongly similar.Follistatin and activin A interact (Shimonaka et al.,1991;Mather et al.,1993)to modulate secretion of FSH in pig(Hafez and Hafez,2000),follicle stimulation hormone regulated spermatogenesis(Zanella et al.,1999; Lunstra et al.,1997),these might be functional evidence for marker FST locus associated with the sperm quality traits.
Hiendleder et al.(2002)found that allele A of INHA occurred with frequency of0.24 in29unrelated individuals of Duroc,German Landrace,Large White,Meishan,and Wild boar,but?ve Meishan pigs were homozygous for the B allele.Meishan breed is known for its better reproductive performances(Borg et al.,1993).Here,we found the B allele to be the predominant in the AI boars.The frequency of B allele of the reproductive gene INHA could have increased among these boars that have been selected for reproduction traits. Some functional evidence for signi?cant association of INHA gene with sperm quality traits is that activation of inhibin-alpha gene during testis development correlated with the histological maturation of the testis and the acquisition of fertility in male(Seok et al., 2004),as well as overexpression of inhibin alpha-subunit gene leading to a disruption of the normal inhibin-to-activin ratio and to reproductive de?ciencies(Cho et al.,2001).
A polymorphism(T>C)at position177(U78106),within exon2of gene LH
B was described by Jiang et al.(1999).In the present study,the allele frequencies hardly showed any difference in both PI and PI×HA breeds and the heterozygote T
C was in both breeds more than40%.Allele frequencies at this locus have not been reported yet for any other
360 C.L.Lin et al./Animal Reproduction Science92(2006)349–363
swine breed.Therefore,no comparison can be made between different breeds.The func-tional evidence arises from LHB gene expressed during spermatogenesis and male sexual behavior and FSHB may participate in spermatogenesis,whereas LHB is more involved in spermatogenesis(Degani et al.,2003).
While this study promotes GNRHR,INHBA and INHBB as candidates for boar fertility traits it reveals no support for effects of PRL,PRLR,FSHB,FST,INHA and LHB on the traits analysed.However,these results do not role out possible impact of these genes on boar fertility.The polymorphism in the genes studied may not directly affect the trait. These polymorphisms could be markers linked with a causative mutation within the gene or a closely linked gene.Different linkage relationships may be the reason estimates of the effects of genes differ across populations(Linville et al.,2001).Moreover,background effects of other genes and interactions of these genes with other genes can also mask the effects and cause estimates of gene effects to differ across populations.Little is known about the magnitude of epistatic effects on the traits studied here.Because of epistasis,polymorphisms for one gene could have a small effect in one population;yet explain a signi?cant portion of the variance in other boar populations.The boars analysed here are those that have been selected for AI;i.e.they represent animals inheriting favourable production performance and exhibiting auspicious reproductive performance.The use of animals with low fertility would increase the power of the analysis for the sperm quality traits as well as fertility traits.
This study elucidated signi?cant association of GNRHR,INHBA and INHBB with sperm quality traits in the boar population.These polymorphisms are markers for potentially linked polymorphisms with impact on protein structure and/or expression level.Polymorphisms of these candidate genes might be used as markers for improving sperm quality traits.However, further validation for the usefulness of these markers is necessary. Acknowledgement
The authors gratefully acknowledge Dr.A.Niggemeyer of the GFS-Ascheberg for pro-viding us with sperm samples and boar reproduction records for this work.
References
Achermann,J.C.,Jameson,J.L.,1999.Fertility and infertility:genetic contributions from the hypothalamic-pituitary-gonadal axis.Mol.Endocrinol.13,812–818.
Aiman,J.,Mcasey,M.,Harms,L.,1998.Serum and seminal plasma prolactin concentrations in men with normo-spermia,oligospermia,or azoospermia.Fertil.Steril.49,133–137.
Bidanel,J.P.,Prunier,A.,Iannuccelli,N.,Milan,D.,2001.Detection of quantitative trait loci for male and female reproductive traits in Meishan×Large White F2pigs.In:Proceedings of The52nd EAAP Annual meeting, Budapest,Hungary,26–29August.
Bo-Abbas,Y.,Acierno,J.S.J.R.,Shagoury,J.K.,Crowley,W.F.J.R.,Seminara,S.B.,2003.Autosomal reces-sive idiopathic hypogonadotropic hypogonadism:genetic analysis excludes mutations in the gonadotropin-releasing hormone(GNRHR)and GNRHR receptor genes.J.Clin.Endocrinol.Metab.88,2730–2737. Bole-Feysot,C.,Gof?n,V.,Edery,M.,Binart,N.,Kelly,P.A.,1998.Prolactin(PRL)and its receptor:actions,signal transduction pathways and phenotypes observed in PRL receptor knockout mice.Endocr.Rev.19,225–268.
C.L.Lin et al./Animal Reproduction Science92(2006)349–363361 Borg,K.E.,Lunstra,
D.D.,Christenson,R.K.,1993.Semen characteristics,testicular size,and reproductive hor-mone concentrations in mature duroc,meishan,fengjing,and minzhu boars.Biol.Reprod.49,515–521. Braundmeier,A.G.,Miller,D.,2001.The search is on:?nding accurate molecular markers of male fertility.J.
Dairy Sci.84,1915–1925.
Campbell,E.M.,Fahrenkrug,S.C.,Vallet,J.L.,Smith,T.P.,Rohrer,G.A.,2001.An updated linkage and compar-ative map of porcine chromosome18.Anim.Genet.32,375–379.
Casas-Carrillo,E.,Prill-Adams,A.,Price,S.G.,Clutter,A.C.,Kirkpatrick,B.W.,1997.Mapping genomic regions associated with growth rate in pigs.J.Anim.Sci.75,2047–2053.
Cassady,J.P.,Johnson,R.K.,Pomp,D.,Rohrer,G.A.,van Vleck,L.D.,Spiegel,E.K.,Gilson,K.M.,2001.Iden-ti?cation of quantitative trait loci affecting reproduction in pigs.J.Anim.Sci.79,623–633.
Cho,B.N.,Mcmullen,M.L.,Pei,L.,Yates,C.J.,Mayo,K.E.,2001.Reproductive de?ciencies in transgenic mice expressing the rat inhibin alpha-subunit gene.Endocrinology142,4994–5004.
Cohen,D.P.,2000.Molecular evaluation of the gonadotropin-releasing hormone receptor.Semin.Reprod.Med.
18,11–16.
Colenbrander,B.,Feitsma,H.,Grooten,H.J.,1993.Optimizing semen production for arti?cial insemination in swine.J.Reprod.Fertil.48(Suppl.),207–215.
Degani,G.,Jackson,K.,Goldberg,D.,Sarfati,R.,Avtalion,R.R.,2003.betaFSH,betaLH and growth hormone gene expression in blue gourami(Trichogaster trichopterus,Pallas1770)during spermatogenesis and male sexual behavior.Zool.Sci.20,737–743.
Ellendorff,F.,Roth,E.,Smidt,D.,1970.The in?uence of FSH,LH and testosterone on the sexual behaviour and testicular function of the boar.J.Reprod.Fertil.21,347–352.
Ellegren,H.,1993.Abundant(A)n·(T)n mononucleotide repeats in the pig genome:linkage mapping of the porcine APOB,FSA,ALOX12,PEPN and RLN loci.Anim.Genet.24,367–372.
Ford,J.J.,Wise,T.H.,Lunstra,D.D.,1997.Negative relationship between blood concentrations of follicle-stimulating hormone and testicular size in mature boars.J.Anim.Sci.75,790–795.
Hafez,B.,Hafez,E.,2000.Reproduction in farm animals,seventh ed.Lea and Febiger.
Hardge,T.,Scholz,A.,Gregor,1995.The in?uence of RYR1genotype on male fertility in pigs.In:Proceedings of The46th EAAP Annual Meeting,Prague,Czech Republic,4–7September,p.268(abstracts). Hiendleder,S.,Reiner,G.,Geldermann,H.,Dzapo,V.,2002.SNPs in the porcine INHA gene and linkage mapping to SSC15.Anim.Genet.33,247–248.
Hondo,E.,Kurohmaru,M.,Sakai,S.,Ogawa,K.,Hayashi,Y.,1995.Prolactin receptor expression in rat sper-matogenic cells.Biol.Reprod.52,1284–1290.
Hu,Y.A.,Huang,Y.F.,2002.A serum marker of spermatogenesis-inhibin B.Natl.J.Androl.8,57–60. Huang,S.Y.,Chen,M.Y.,Lin,E.C.,Tsou,H.L.,Kuo,Y.H.,Ju,C.C.,Lee,W.C.,2002.Effects of single nucleotide polymorphisms in the5 -?anking region of heat shock protein70.2gene on semen quality in boars.Anim.
Reprod.Sci.70,99–109.
Huhtaniemi,I.,Jiang,M.,Nilsson,C.,Pettersson,K.,1999.Mutations and polymorphisms in gonadotropin genes.
Mol.Cell Endocrinol.25(151),89–94.
Jiang,Z.H.,Gibson,J.P.,Archibald,A.L.,Haley,C.S.,2001.The procine gonadotropin-releasing hormone receptor gene(GNRHR):genomic organization,polymorphisms,and association with the number of corpora lutea.
Genome44,7–12.
Jiang,Z.H.,Rottmann,O.J.,Pirchner,F.,1999.Identi?cation and characterization of genetic polymorphisms at exon2of porcine FSHB and LHB genes.Available from:https://www.doczj.com/doc/a811886971.html,/entrez/viewer. Kaipia,A.,Penttila,T.L.,Shimasaki,S.,Ling,N.,Parvinen,M.,Toppari,J.,1992.Expression of inhibin beta A and beta B,follistatin and activin-A receptor messenger ribonucleic acids in the rat seminiferous epithelium.
Endocrinology131,2703–2710.
King,A.H.,Jiang,Z.,Gibson,J.P.,Haley,C.S.,Archibald,A.L.,2003.Mapping quantitative trait loci affecting female reproductive traits on porcine chromosome8.Biol.Reprod.68,2172–2179.
Kmiec,M.,Zimemak,J.,Dybus,A.,Matusiak,S.,2002.Analysis of relations between polymorphism in steroid 21-hydroxylase gene(CYP21)and quantitative and qualitative characters of boar semen.Czech.J.Anim.Sci.
47,174–199.
Korwin-Kossakowska,A.,Kamyczek,M.,Cieslak,D.,Pierzchala,M.,Kuryl,J.,2003.Candidate gene markers for reproductive traits in polish990pig line.J.Anim.Breed.Genet.120,181–191.
362 C.L.Lin et al./Animal Reproduction Science92(2006)349–363
Layman,L.C.,2000.Mutations in the follicle stimulating hormone beta(FSHB)and FSH receptor genes in mice and humans.Semin.Reprod.Med.18,5–10.
Layman,L.C.,Peak,D.B.,Xie,J.,Sohn,S.H.,Reindollar,R.H.,Gray,M.R.,1997.Mutation analysis of the gonadotropin-releasing hormone receptor gene in idiopathic hypogonadotropic hypogonadism.Fertil.Steril.
68,1079–1085.
Li,M.D.,Macdonald,G.J.,Wise,T.,Ford,J.J.,1998.Positive association between expression of follicle-stimulating hormone beta and activin beta B-subunit genes in boars.Biol.Reprod.59,978–982.
Linville,R.C.,Pomp,D.,Johnson,R.K.,Rothschild,M.F.,2001.Candidate gene analysis for loci affecting litter size and ovulation rate in swine.J.Anim.Sci.79,60–67.
Lunstra,D.D.,Ford,J.J.,Klindt,J.,Wise,T.H.,1997.Physiology of the Meishan boar.J.Reprod.Fertil.Suppl.
52,181–193.
Malmgren,L.,Larsson,K.,1984.Semen quality and fertility after heat stress in boars.Acta Vet.Scand.25, 425–435.
Mather,J.P.,Roberts,P.E.,Krummen,L.A.,1993.Follistatin modulates activin activity in a cell-and tissue-speci?c manner.Endocrinology132,2732–2734.
Meinhardt,A.,O’bryan,M.K.,Mcfarlane,J.R.,Loveland,K.L.,Mallidis,C.,Foulds,L.M.,Phillips,D.J.,de Kretser,D.M.,1998.Localization of follistatin in the rat testis.J.Reprod.Fertil.112,233–241.
Milan,D.,Bidanel,J.P.,Iannuccelli,N.,Riquet,J.,Amigues,Y.,Gruand,J.,Le Roy,P.,Renard,C.,Chevalet,C., 2002.Detection of quantitative trait loci for carcass composition traits in pigs.Genet.Sel.Evol.34,705–728. Moran,C.,1993.Microsatellite repeats in pig(sus domestica)and chicken(gallus domesticus)genomes.J.Hered.
84,274–280.
Nonneman,D.,Rohrer,G.A.,2003.Molecular cloning of the porcine inhibin-beta B gene and reassignment to chromosome15.Anim.Genet.34,213–215.
Plant,T.M.,Marshall,G.R.,2001.The functional signi?cance of FSH in spermatogenesis and the control of its secretion in male primates.Endocr.Rev.22,764–786.
Rathje,T.A.,Rohrer,G.A.,Johnson,R.K.,1997.Evidence for quantitative trait loci affecting ovulation rate in pigs.J.Anim.Sci.75,1486–1494.
Raymond,M.,Rousset,F.,1994.Population genetics software for exact test and ecumenicism.J.Hered.86, 248–249.
Risbridger,G.P.,Thomas,T.,Gurusinghe,C.J.,Mcfarlane,J.R.,1996.Inhibin-related proteins in rat prostate.J.
Endocrinol.149,93–99.
Rohrer,G.A.,1999.Mapping four genes from human chromosome4to porcine chromosome8further develops the comparative map for an economically important chromosome of the swine genome.Anim.Genet.30, 60–62.
Rohrer,G.A.,Alexander,L.J.,Beattie,C.W.,1994.Mapping the?subunit of follicle stimulating hormone(FSHB) in the porcine genome.Mamm.Genome5,315–317.
Rohrer,G.A.,Wise,T.H.,Lunstra,D.D.,Ford,J.J.,2001.Identi?cation of genomic regions controlling plasma FSH concentrations in Meishan-White composite boars.Physiol.Genomics6,145–151.
Rothschild,M.F.,Jacobson,C.,Vaske,D.,Tuggle,C.,Wang,L.,Short,T.,Eckardt,G.,Sasaki,S.,Vincent,A., Mclaren,D.,Southwood,O.,van der Steen,H.,Mileham,A.,Plastow,G.,1996.The estrogen receptor locus is associated with a major gene in?uencing litter size in pigs.Proc.Natl.Acad.Sci.93,201–205. Shimonaka,M.,Inouye,S.,Shimasaki,S.,Ling,N.,1991.Follistatin binds to both activin and inhibin through the common subunit.Endocrinology128,3313–3315.
See,M.T.,2000.Selection for AI Stud traits.In:Record of Proceedings National Swine Improvement Federation Conference and Annual Meeting,Nashville,Tennessee,USA,7–8December(NSIF25).
Seminara,S.B.,Hayes,F.J.,Crowley,W.F.J.R.,1998.Gonadotropin-releasing hormone de?ciency in the human (idiopathic hypogonadotropic hypogonadism and Kallmann’s syndrome):pathophysiological and genetic con-siderations.Endocr.Rev.19,521–539.
Seok,O.S.,Ahn,J.M.,Mayo,K.E.,Cho,B.N.,2004.Developmental changes in inhibin-alpha gene expression in the mouse testis.Mol.Cells29(17),67–72.
Steinheuer V on,R.,Dr¨o gem¨u ller,C.,Hamann,H.,G¨o tz,K.-U.,Distl,O.,2002.Sch¨a tzung von Kandidatengenef-fekten auf die Anzahl lebend geborener Ferkel bei Sauen und Ebern der Deutschen Landrasse.Z¨u chtungskunde 74,276–287.
C.L.Lin et al./Animal Reproduction Science92(2006)349–363363 Steinheuer V on,R.,Dr¨o gem¨u ller,C.,Hamann,H.,G¨o tz,K.-U.,Distl,O.,2003.Ein?uss von Kandidatengeneffekten auf die Anzahl lebend geborener und aufgezogener Ferkel bei Besamungsebern der Deutschen Landrasse.
Z¨u chtungskunde75,204–213.
Tamaya,T.,2002.Normosmic idiopathic hypogonadotropic hypogonadism with GNRHR receptor mutation.Jpn.
J.Clin.Med.(Osaka)60,319–324.
Urban,T.,Kuciel,J.,2001.The effect of point mutation in RYR1gene on the semen quality traits in boars of Large White and Landrace breeds.Czech.J.Anim.Sci.46,460–464.
Vasquez,J.M.,Ben-Nun,I.,Greenblatt,R.B.,Mahesh,V.B.,Keel,B.A.,1986.Correlation between follicle-stimulating hormone,luteinizing hormone,prolactin,and testosterone with sperm cell concentration and motility.Obstet.Gynecol.67,86–90.
Vincent,A.L.,Wang,L.,Tuggle,C.K.,Robic,A.,Rothschild,M.F.,1997.Prolactin receptor maps to pig Chro-mosome16.Mamm.Genome8,793–794.
Vincent,A.L.,Evans,G.,Short,T.H.,Southwood,O.I.,Plastow,G.S.,Tuggle,C.K.,Rothschild,M.F.,1998a.The prolactin receptor gene is associated with increased litter size in pigs.In:Proceedings of the6th WCGALP, vol.27,Armidale,Australia,11–16January,pp.15–18.
Vincent,A.L.,Wang,L.,Tuggle,C.K.,Rothschild,M.F.,1998b.Linkage and physical mapping of prolactin to porcine chromosome7.Anim.Genet.29,27–29.
Zanella,E.,Lunstra,D.,Wise,T.,Kinder,J.,Ford,J.,1999.Testicular morphology and function in boars differing in concentration of plasma follicle-stimulating hormone.Biol.Reprod.60,115–118.
种猪精子和卵子在子宫内的存活时间 来源: https://www.doczj.com/doc/a811886971.html,山东价格网编辑:王华鑫2012年11月10日星期六 成熟卵子从卵巢排出以后，其存活时间是有限的，精子在子宫的存活时间也是有限的，把握好了这两个时间，在正确时候进行人工授精，才能提高受胎率。 1. 精子在子宫内的运输 精子在子宫内的运输主要是依靠外力、子宫的收缩及输卵管收缩和纤毛的摆动而到达受精部位。猪精子进入母猪的生殖管道后，将开始“艰难地跋涉”，它们一部分贮存在子宫内陷窝中形成若干个精子贮库，精子在这些贮库中不断释放，以保证受精部位总是不断有受精能力的精子出现，等待卵子的到来。 精子沿着母猪的生殖管道向前进行，密度呈现一个梯度状的减少，在子宫颈部分精子密度最高，达100000000个以上，而到达输卵管的上段精子的密度仅为1000个(受精部位)。猪精子的这种高选择性和运行期间的巨大损耗，使更有生命力、活性最好的精子才有可能达到受精部位，同时也限制了到达受精部位的精子数目，而绝大多数的精子则被白细胞吞食或杀死。 2. 精子维持受精能力的时间 精子由公猪体内排出后维持受精能力的时间为24-42h。母猪的卵子生存时间仅为8-12个h，只有当精子和卵子都保持较好的活力，才有可能获得较好的受胎率。而当精子或卵子有一方老化，都会导致受胎率的下降，这说明正确的发情鉴定及适时输精对于提高受胎率至关重要。 3. 精子的损失 授精或者紧张导致子宫收缩加剧，都会减少有效精子数，白细胞的吞噬也使精子损失。此外，子宫或者输卵管有可能产生抗精子的抗体，使受精力下降。 4. 卵子的运输 母猪的卵子可以由卵泡表面进入到输卵管的伞口部，并很快沿着薄壁的伞部进入到壶峡结合部的受精部位。 5. 卵子的老化 如果卵子排出后进入受精部位但未能及时与精子相遇并受精，那么卵子将很快老化。这种变化在排卵后12h十分明显，因此说明，配种或人工授精一定要在排卵前的适宜时间进行，否则卵子就有可能老化。根据精子在母猪生殖道中运行的速率及保持受精能力的时间推测，
精子卵细胞的形成及受精作用 开课教师：胡彬 开课班级：高二（5）班 开课时间：2006年12月21日教学目标 知识与技能 1．掌握精子和卵细胞的形成过程； 2．减数分裂和受精作用的意义。 过程与方法 1．通过学习精子和卵的形成过程，进一步掌握减数分裂过程中染色体行为的变化； 2．通过对精子和卵形成过程的比较，提高自身的归纳、总结、比较能力。 情感态度与价值观 通过本节课的学习，明白世界上的每一个人都是一个独立而又唯一的个体，能够健康的来到这个世界是多么的幸运和不容易，要尊重和珍爱自己、他人的生命。 教学重点 精子和卵细胞的形成过程 教具准备 多媒体课件、自制染色体磁性贴 教师结合减数分裂图讲 述精子形成过程，及各分裂 段细胞的名称。
知识介绍：在变形的过程中，精细胞的细胞核集中在精子的头部，部分细胞质集中在精子的颈部和长长的尾部， 教师介绍卵巢是形成卵细胞的场所。卵巢中的卵原细胞，通过减数分裂产生卵细胞。请学生观察书上卵细
学生任务
课后反思 比较满意的地方 1．制作了染色体磁性贴，传统与现代教学技术有机结合。本节课将“减数分裂各时期细胞内染色体行为变化”在学习“精子和卵细胞形成过程”之前作为复习引入。一方面要求学生在练习纸上画出减数分裂各时期细胞内染色体的行为，另一方面由一位学生用磁性贴到黑板上排出，目的是为了检查学生是否掌握好了此内容。通过教学发现磁性贴的好处是便于修改，而用多媒体课件就无法做到这点。 2．利用“受精作用及胎儿在母体内孕育过程”录象来激发学生对生命的感悟，学生对此录象非常感兴趣，课上有的学生说：“生命太奇妙了”，有的说：“人真是太强大了”，有的说：“要珍惜自己的生命”。通过学生谈观后体会，在无形中渗透了生命教育。 3．整节课思路比较清晰，各知识点之间过渡衔接较好。通过设疑—思考—回答、课上画或排染色体行为变化和归纳总结精卵形成过程不同点来落实重点，引导学生积极主动参与到教学中。 不足之处 课堂气氛沉闷。一方面教学内容较难，本人也发现科普类的课简单与生活较贴近，学生总能说出点什么，容易调动气氛。而知识点较复杂的课，课堂气氛总是不尽人意。另一方面由于听课教师、家长太多（整整塞满了一个教室，还有很多老师搬着凳子坐在外面，通过窗户听课），在这样的一个环境中，开课班级学生出现了与平时截然不同的反应，甚至是很奇怪的现象，本来观看录象是本节课的高潮部分，很多班级看到此内容，都会发出感叹忍不住要议论纷纷，而开课的班级学生竟然只是仰着头看，没有发出任何的声音，教室里异常地安静。这又使我发现了两个值得探究的地方，一个是教学内容既然很难，那么教师如何来调动学生的课堂气氛；另一个是我觉得教师应当在开课之前关心学生的心理，因为每次开课我们似乎都只考虑到教师会紧张，而学生呢？其实学生也会很紧张，怕说错了丢教师和自己的面子，所以作为老师应当在开课之前关心一下你的学生，帮助他们减减压，对学生进行适当的心理辅导也是一种生命的教育。最后使学生能够明白：区级公开课不光是在提高教师的专业
姓名：谭克强 专业：生物技术 学号：2009211803 比较精子和卵子的形成过程。 答：人体的基本构造是由数以百万亿计的细胞组成的，人类的繁衍同样靠细胞支持。人类具有两种细胞，一种是体细胞，如构成心、肝、肺、肾、肌肉、骨骼等人体器官的都是体细胞，而另一类则生衍后代性细胞。性细胞又叫生殖细胞，在男性，就是精子；女性则为卵子。 精子是在男性睾丸内生成的。其生殖的基础，是由几百万条曲细精管内产生的。曲细精管生精上皮的精原细胞，是生殖的基础。 曲细精管生精上皮的精原细胞经过多次分裂，最后成熟为精子，这个过程也需要一定的时间，一般需要75天左右。 男性青春发育以后，睾丸便拥有延续不断的生精能力。成年男人的睾丸重约10--20克，而平均每克睾丸组织每天可产生约1千万个精子。一般到40岁后，生精能力逐渐减弱。 精原细胞经过前期的染色体复制进入减数第一次分裂，同源染色体分离，变成两个次级级精母细胞，进入减数第二次分裂，类似有丝分裂，着丝体分离，变成4个精细胞，然后变形为4个精子，每个精子之含有体细胞染色体数的一半。
女人的生殖基础是卵子，卵子由卵巢产生，但卵巢常常受多方面的影响。 卵子是由卵巢生卵上皮的原始卵母细胞发育成熟而成。原始卵母细胞和它周围的一层颗粒细胞构成一个原始卵泡，胎儿卵巢内原始卵泡多达二百万个。 但是，这些数量的原始卵泡在出生后大部分退化，到青春期仅仅剩下三万个左右。卵巢的生卵作用是不连续的。一个妇女一生约排出400个卵子，最多也不过500个。 卵原细胞经过前期的染色体复制进入减数第一次分裂，同源染色体分离，变成1个次级卵母细胞和一个集体，一个大一个小，进入减数第二次分裂，类似有丝分裂，着丝体分离，变成4个细胞，由次级卵母细胞分裂的大的为卵细胞，小的和另一个集体分裂成的两个集体构成3个集体，每个卵子之含有体细胞染色体数的一半。
受精到胚胎发育全过程 作者：佚名2005-2-8 受精和胚胎发育是生命的开始，每个人都要经历，但大多数人都一头雾水。心里有好多疑惑，可又不好意思问出口。那就看看这里吧！ 受精 精子 精子是男性的生殖细胞，由睾丸产生，平时就储存在睾丸和附睾里。正常男子每次射出精液2～6毫升，每毫升约有0.6～1.5亿个精子。射出的精子依靠鞭毛的摆动奋力向前游去，与等候在输卵管的卵子结合。 成熟卵泡（箭头所指处） 卵子是女性的生殖细胞，由卵巢产生并排出。女性进入生育期以后，卵巢每月会排出一个卵子，有时 可以排两个。卵子从卵巢排出后进入输卵管内，停留在输卵管的峡部与壶腹部的交界处等待受精。
性交过程 男性通过性交将精液射入女性的阴道内，精子离开精液经宫颈管进入宫腔，当精子与卵子相遇，精子通过酶的作用得以穿过卵子的外围到达卵子的表面，一当精子与卵子表面接触便开始了受精过程。到达卵子表面的精子会借助尾部的摆动而进入卵子的内部。 受精卵（箭头所指分别为精原核和卵原核） 精子和卵子各带23条染色体，受精即精子和卵子的染色体结合，这样就有了46条染色体，受精卵由单细胞分裂成两个相同的细胞，并慢慢向宫腔移动，边移动边分裂，到子宫时已成为约有48个细胞的中空团块，叫胚泡或囊胚，进行下一步的植入。 受精卵的发育与着床
卵子受精后即开始有丝分裂，并在一边分裂的同时一边向子宫腔方向移动。受精卵在输卵管内36小时后分裂为2个细胞，72小时后分裂成16个细胞，叫桑椹胚。受精后第4日，细胞团进入子宫腔，并在子宫腔内继续发育，这时，细胞已分裂成48个细胞，成为胚泡准备植入。胚泡可以分泌一种激素，帮助胚泡自己埋入子宫内膜。受精后第6-7日，胚泡开始着床。着床位置多在子宫上1/3处，植入完成意味胚胎已安置，并开始形成胎盘，孕育胎儿了。 1、受精卵 2、精原核和卵原核开始互相融合 3、受精卵开始有丝分裂 4、几近完成的有丝分裂
精子与卵子“终成眷属”说媒人”功不可没 输卵管位于女性盆腔内，左右各一，是女性体内一对细长的管状器官，其重要任务是运送卵子和精子，输卵管的中部（即壶腹部）较宽，是卵子和精子相遇结合的地方。 女性排卵时，成熟的卵子离开它的母体卵巢，投入输卵 管的腹腔开口处一一输卵管伞部的怀抱。由于上皮细胞纤毛的摆动，几分钟后，卵子即被送入输卵管的壶腹部稍作停留，卵子外围保护层中排列紧密的冠状细胞松散，等待精子的到来。 性生活时，精子从阴道经过重重关卡，来到输卵管壶腹部，与卵子相遇，就像“牛郎”与“织女”相会于“鹊桥” 当它们激情相拥融为一体时，人类的新生命一一受精卵就此诞生。 输卵管不畅：精子、卵子“终生不见” 输卵管的管腔较为狭窄，最狭窄部分直径仅为1?2毫米。如果输卵管邻近器官出现炎症，如阑尾炎感染可蔓延至输卵管，导致输卵管粘连、盆腔粘连。阴道炎、宫颈炎、子宫内膜炎等上行感染，人工流产、上环、输卵管通液术等宫腔手术后发生生殖器炎症，也会导致输卵管堵塞。当发生输卵管炎或盆腔炎时，输卵管的最狭窄部分及伞 端很容易发生 粘连或完全闭锁。 “鹊桥”输卵管的通畅是受孕必不可少的条件之一。当出现以上这些情况时，“精子牛郎”与“卵子织女”就会被生生分隔于“鹊桥”两
端而不能相见，郁郁而终。 精子卵子“说媒人” ：“五联疗法” “鹊桥”输卵管的通畅是顺利孕育的重要环节。当输卵管有问题时，精子与卵子无法结合，女性也就无法怀孕。 输卵管炎性不孕症的治疗原则是疏通管腔，恢复功能。炎症造成的管壁毛糙、僵硬、管腔狭窄，仅靠手术无法解决问题，且术后可能重新粘连，使患者仍然不孕或发生异位妊娠。这时，如果有位“说媒人”打通“鹊桥” ，就能让“精子牛郎”与“卵子织女”相会。这位“说媒人” （“五联疗法+”）擅长中西医结合方法，可以帮助炎症增生组织 的软化吸收，恢复输卵管的蠕动功能，5 名“兄弟”加1 名“义弟” 完成。 “五兄弟”的老大是患者每天口服的中药，具有针对性强、药味少、花费低的特点。输卵管性不孕症分为三型，这三型都离不开一个“瘀”字。血瘀是输卵管炎性不孕症的主要病机，活血化瘀是基本治法，治则多以活血化瘀、软坚散结为主。多选用活血化瘀中药，如三棱、莪术、当归、丹参、桃仁、红花、赤芍等2?4味。病久气血耗 伤，常可因瘀致虚，故治疗时应注意辨别虚实寒热。 老二仍是中药，但独辟蹊径，采用中?保留灌肠，可使药 物通过肠道直接吸收，促使病变部位血管扩张，病灶粘连松解，加速管腔疏通，且药效不受消化道诸多因素的影响，维持时间长。温热的药液在直肠中，还可改善盆腔血液循环，加速炎症物质吸收，软化增生组织。
生命的开始精子和卵子相遇全过程 【摘要】生命的开始是一个神奇的过程，同房后，精子开始走上了漫漫寻爱之旅。精子同卵子要“相会”，至少要过４关：即通过阴道，穿过子宫颈，在宫腔内运行，最后进入输卵管同卵子“相会”。一起来直击卵子与精子相遇过程。 生命的开始是一个神奇的过程，当精子遇上了卵子，它不早不晚，时机刚刚好，才有了受精卵，受精卵在子宫里发育为胎儿，妈妈十月怀胎，直到新生命降临。 看起来这个过程都是那么顺理成章，但是大家知道吗？要让精子与卵子的相遇时机刚刚好，却不是一件随随便便就可以实现的事情。因为正常女性一个月只排出1个卵子，而卵子的存活时间只有1~2天，如何让精子在卵子最美的时候相遇？抓住排卵期和排卵日就变得很 有必要哦。
什么是排卵期？ 正常育龄女性每个月来1次月经，从本次月经来潮开始到下次月经来潮第1天，称为1个月经周期。 排卵发生在两次月经中间。女性的月经周期有长有短，但排卵日与下次月经开始之间的间隔时间比较固定，一般在14天左右。所以排卵日推算法就是从下次月经来潮的第1天算起，倒数14天就是排卵日。卵子排出后在输卵管内能生存1-2天，精子在女子的生殖道内可维持2-3天受精能力，故在卵子排出的前后几天里性交容易受孕。为了保险起见，将排卵日的前5天和后4天，连同排卵日在内共10天称为排卵期。
找准排卵日比推算的排卵期更靠谱 为什么卵子的生存时间只有1~2天，但是排卵期却有10天那么 长呢？那是因为排卵也会受到环境、心情、饮食等因素的影响而发生改变（这就是为什么我们的月经周期不会永远都固定为30天或28天），因为排卵日会有小幅的浮动，就只能用一个大概的时间段来推算排卵期，卵子排出后有1~2天的存活时间。精子在女性生殖道里可存活2～3天，而受精能力多在排卵后的24小时之内，超过2～3天精子即失去与卵子结合的能力。因此，在排卵前2～3天和排卵后1～2天同房，才更有机会受孕。所以，利用辅助工具（例如排卵测试笔等）找准排卵的那2天，比推算出来10天的排卵期更加靠谱。 在排卵期的相爱精子和卵子相遇全过程 排卵之后同房了，精子开始走上了漫漫寻爱之旅。精子同卵子要“相会”，至少要过４关：即通过阴道，穿过子宫颈，在宫腔内运行，最后进入输卵管同卵子“相会”。 在排卵期，宫颈粘液助精子一臂之力：在排卵期，子宫粘液量多而稀薄，便于精子通过；同时宫颈粘液中白细胞数量减少，从而减少了吞吃精子的机会；另外，此时子宫颈粘液碱性增强，而精子正是喜碱厌酸，故起到了保护精子的作用。而在其他时期，子宫颈粘液少而
受精到胚胎发育全过程加上减数分裂从无性人体实在来不及同时进化出男女世蔚摘要自网页 作者：佚名2005-2-8 受精和胚胎发育是生命的开始，每个人都要经历，但大多数人都一头雾水。心里有好多疑惑，可又不好意思问出口。那就看看这里吧！ 受精 精子 精子是男性的生殖细胞，由睾丸产生，平时就储存在睾丸和附睾里。正常男子每次射出精液2～6毫升，每毫升约有0.6～1.5亿个精子。射出的精子依靠鞭毛的摆动奋力向前游去，与等候在输卵管的卵子结合。 成熟卵泡（箭头所指处） 卵子是女性的生殖细胞，由卵巢产生并排出。女性进入生育期以后，卵巢每月会排出一个卵子，有时 可以排两个。卵子从卵巢排出后进入输卵管内，停留在输卵管的峡部与壶腹部的交界处等待受精。
性交过程 男性通过性交将精液射入女性的阴道内，精子离开精液经宫颈管进入宫腔，当精子与卵子相遇，精子通过酶的作用得以穿过卵子的外围到达卵子的表面，一当精子与卵子表面接触便开始了受精过程。到达卵子表面的精子会借助尾部的摆动而进入卵子的内部。 受精卵（箭头所指分别为精原核和卵原核） 精子和卵子各带23条染色体，受精即精子和卵子的染色体结合，这样就有了46条染色体，受精卵由单细胞分裂成两个相同的细胞，并慢慢向宫腔移动，边移动边分裂，到子宫时已成为约有48个细胞的中空团块，叫胚泡或囊胚，进行下一步的植入。 受精卵的发育与着床
卵子受精后即开始有丝分裂，并在一边分裂的同时一边向子宫腔方向移动。受精卵在输卵管内36小时后分裂为2个细胞，72小时后分裂成16个细胞，叫桑椹胚。受精后第4日，细胞团进入子宫腔，并在子宫腔内继续发育，这时，细胞已分裂成48个细胞，成为胚泡准备植入。胚泡可以分泌一种激素，帮助胚泡自己埋入子宫内膜。受精后第6-7日，胚泡开始着床。着床位置多在子宫上1/3处，植入完成意味胚胎已安置，并开始形成胎盘，孕育胎儿了。 1、受精卵 2、精原核和卵原核开始互相融合 3、受精卵开始有丝分裂 4、几近完成的有丝分裂
精子如何与卵细胞结合 罗密欧和朱丽叶的艰辛爱情算啥？精哥哥想见到卵MM，那就是九死一生哪！来看看精哥哥不平凡的一生吧！ 酸物质洗礼 当男主人努力贡献了那一抹暖流之后，夺冠率为亿分之一的生命竞赛就开始了。精哥哥朝着心中那唯一的圣地进发，它们遇到的第一道障碍就是PH为酸性的阴道环境。 阴道酸性环境的pH值为3.5～4。在这样艰苦的酸性环境里，大部分精哥哥进入阴道没多久就死光了，极少数生命力顽强的精哥哥才能获得进入子宫的机会。在这一场酸性战役中，那些有体力没脑力的、有脑力没体力的、没脑力没体力的家伙会被秒杀。剩余的精哥哥会在90-180秒之内到达子宫颈口，然而你以为这样就结束了吗？它们还要面对下一场考验。 子宫粘液障碍 女主人在排卵期，粘液量更多，变清，外流。精哥哥会到达子宫颈处，此时“宫颈粘液”的像考试官一样对精哥哥们进行验身。游不快的不要，体力不好的不要，没有八块腹肌的不要...那些没有被选中的精哥哥，会流出女主人体外，完成他悲催而短暂的一生。一般情况下，啪啪后2小时，90%精哥哥都阵亡了。 子宫腔内考验重重 剩下10%的精哥哥并不都是精华，进入子宫腔后，又开始了一场智慧PK！在这里它们会遭遇子宫腔设置的各种陷阱：粘液、绒毛、死角、旋涡、褶皱，如果不小心误入歧途，只能沦为白细胞的盘中餐。 向左走还是向右走 通过陷阱考验的精子，终于离成功只有一步之遥。却有一个残酷的现实：一般情况，女主人每次只排出一个卵MM，两侧卵巢交替排卵。然而哪边卵巢排卵，在“岔路口”并没有提示路标，所有剩下的精哥哥中有50%踏上永远不能见到卵MM的歧途。 直接竞争 选对路的精哥哥，会在输卵管稍做休息，精心打扮一下，等待卵MM出现，其中只有一个幸运者会获得卵MM垂青，结合成受精卵，所以在这场上亿人的战场中只有那一人获胜。是不是很残酷？但是只有这样的筛选机制才能帮助卵美美找到最佳伴侣呢！ 突然胃痛怎么快速缓解 有时候一些人会突然发生胃痛的现象，其实胃痛疾病是很常见的，所以说当出现胃痛的时候，也一定要掌握他的一些快速缓解方法，因为这样的话才能给自己减轻病痛。那么突然，胃痛怎么快速缓解呢？都有哪些好的处理方法呢？下面就跟大家分享一下。 突然胃痛怎么快速缓解
精子与卵子的约会激情过后，陈蓉望着身边渐渐沉重梦乡的方建业，嘴角轻轻地向上扬起。高潮时小腹传来的轻微抽动现在还令她快乐地战栗。大学那会儿，陈蓉是历史系小有名气的美女加才女，追求陈蓉的男生可不少，其中还不乏佼佼者。但是陈蓉偏偏选中了数学系的方建业。她看中的是方建业的沉稳踏实。大学毕业后，两人就结婚了，陈蓉成了一位中学历史老师，方建业则进了一家企业。婚后的生活充满着安宁的幸福，他们决定要一个小孩。她希望这一次方建业的精子能顺利进入体内，和卵子结合，早日实现自己做妈妈的愿望。 事实上，精子和卵子的约会并不容易。女人在一年间，只有30天有机会受孕。就算是在那些日子里，成功受孕也需要一连串没有关系的事件配合得天衣无缝。成功与否全要看女人自青春期即展开的周期。 ★卵巢的结构 当女性进入青春期后，卵巢会发生一系列的变化。卵巢是两个像核桃一样的器观，分别位于女性的骨盆两侧，它们不仅分泌造成青春期的荷尔蒙，同时也含有创造新生命的原材料：女性的卵子。每个卵巢中含有十万个以上的卵子，从青春期开始，女性大脑中的脑下垂体每个月都会告诉她释放一个卵子。有两根输卵管连接着卵巢与子宫。经过输卵管，卵子要花三天才能完成从卵巢到子宫这段15公分的距离。
在这里，卵子等待着精子的到来。和卵子一起被排出的，还有大约500多个营养细胞，它们是一些黏糊糊的近乎透明的东西，它们裹挟着卵子，为卵子提供所需的营养。女人的一生只能排卵400次，这是创造新生命的机会。 ★精子的结构 精子就像小蝌蚪，头部近圆柱形，尾部细长。男性自青春期后，一生当中都能够产生精子。而且他们产生精子的速度很快，每秒可以产生数千个精子。男性一次射精就可以射出5亿个精子，但这其中，仅有一个可能使一个卵子受精。 精子经过睾丸中错综复杂的管道到达勃起的阴茎，这个距离将近一公尺，它们身处的白色液体不过是补充它们长途旅行所需的营养物质。在高潮来临时，肌肉收缩，将这些液体从男人体内一路送到女人阴道内。 女性的阴道壁是酸性的，以保护她不受细茵感染，但对精子来说，这却是致命的。一个小时内，5亿精子死伤过半。幸存的精子依然勇猛地往子宫进发。但是，这段路程依然曲折。从阴道通往子宫的路并非直线，它是一个90度的转角。 ★精子在子宫内的运动 子宫的形状像一个倒放的梨子，由一堆的肌肉组织形成。子宫最狭窄的那端约有3厘米的部分露出于阴道内，这就是子宫颈。在子宫颈内，有一根导管通往阴道，而这也正是精子们到达子宫的唯一途径。子宫颈里充满着黏液，它们
如对您有帮助，可购买打赏，谢谢 精子和卵细胞结合介绍 导语：日常生活中各位男女朋友，相信都知道要如何进行孕育一个健康的宝宝，是需要健康的精子和卵子细胞结合，那么有的朋友就会出现不孕不育，这就 日常生活中各位男女朋友，相信都知道要如何进行孕育一个健康的宝宝，是需要健康的精子和卵子细胞结合，那么有的朋友就会出现不孕不育，这就代表着精子和卵子出现了一定的问题，无法进行结合，那么这是什么原因造成的呢？接下来为大家介绍一下。 当成熟的卵子离别它的母体——卵巢后，就投入了输卵管伞部的怀抱，由于上皮细胞纤毛的摆动，几分钟后即被送人。输卵管的腹腔开口处，而来到壶腹部。在那里它将稍作停留，并使外围保护层中排列紧密的冠状细胞松散，以等待精子的到来。当精子冲破重重障碍而来到输卵管与卵子相遇时，两者并不能马上结合。结合前需经过两个重要的过程： 第一过程是要破除卵子外围的保护层；它们由丰富的粘多糖和糖蛋白组成，这些保护层阻止精子与卵子结合。因此精子必须释放一系列的酶，以消化粘多糖与蛋白质，才能使三个保护层溶解。这些酶平常存在于精子头部的顶体内，只有在顶体膜破裂后才能释放出来。这一破裂和释放的过程被称为顶体反应。顶体酶系中含有好几种酶，如酸性水解酶、透明质酸酶、放射冠分散酶及顶体蛋白酶等，都是溶解保护层的重要酶。当精子越过卵丘和放射冠后，便同透明带表面疏松地粘着。这时树透明带内外表面各点上的受体便对精子进行识别，这种识别保证了人卵子只能和人精子结合的专一性。经过识别后，透明带才分解，允许精子进入卵细胞内。 了解了精子和卵细胞结合的，过程相信各位朋友们对此有了一定详生活中的小知识分享，对您有帮助可购买打赏
精子与卵子受精过程 准爸爸的精子和准妈妈的卵子相遇，结合在一起形成了受精卵，一个新生命从这里开始。在未来的几个月，胎宝宝就开始在子宫内发育了。那么精子与卵子受精过程是什么样子呢？和妈网编辑一起来了解一下。 1、一次性交会有3亿精子进入阴道 精子从阴道到达输卵管最快时间仅需数分钟，最迟4-6小时，一般1-1.5小时。精子在前进过程中，沿途要受到子宫颈粘液的阻挡和子宫腔内白细胞的吞噬，最后到达输卵管的仅有数十条至一二百条。精子在和卵子受精前还要在女性生殖腔内经过一段时间的孵育后，经过形态、生理、生化的改变，才具有受精能力，这个过程称为精子获能。 2、精子与卵子结合的奇妙瞬间 进入了女性的阴道后，精子们立即就开始了长时间的游泳，从阴道游到子宫的入口。顺利通过关卡”的精子大约是射精时的千分之一。这以后，他们以每分钟2-3毫米的速度往前游，这时，落后的精子是数之不尽的：有些体力不济的中途歇气了；有些没有干劲的早就放弃了；还有些在原地打转；有的则走错了方向。坚持到最后、一直游泳着的精子，数目还不到200。 3、精子与卵子相结合 精子在女性输卵管内能生存1-3天，卵子能生存1天左右，如在女子排卵日前后数天内性交，精子和卵子可能在输卵管壶腹部相遇，这时一群精子包围卵子，获能后的精子其头部分泌顶体酶，以溶解卵子周围的放射冠和透明带，为精子进入卵子开通道路，最终只有一条精子进入卵子，精子完全进入卵子体内以后，通过核的融合，使父、母各23条染色体结合成为46条（23对）染色体，然后形成一个新的细胞，这个细胞称为受精卵或孕卵，这个过程称为受精。这是一个新生命的开始。 受精卵在受精后24小时即进行细胞分裂。受精卵从输卵管分泌的液体中吸取营养和氧气，不断进行细胞分裂。与此同时，通过输卵管的蠕动，受精卵逐渐向宫腔方向移动，3-4天后到达宫腔。 4、受精后8天，胚牙嵌入子宫内膜 3-4天后到达宫腔时已发育成为一个具有12-16个细胞的实心细胞团，形状象桑椹，所以称为桑椹胚。桑椹胚在子宫腔内继续细胞分裂，体积增大，出现腔隙及细胞液。此时的受精卵称为囊胚或胚泡。大约在受精后6-8天胚泡的透明带消失而进入子宫内膜，这个过程，即孕卵植入，叫做着床或种植。此过程大约需要4-5天。孕卵着床的部位多在子宫腔上部的后壁，其次为前壁，偶见于侧壁。当受精卵在子宫着床时你可能会有些感觉，就是轻微的出血现象。 5、胚胎逐渐发育成胎儿 胚泡着床后其细胞继续进行分化，形成三个胚层：外胚层、中胚层及内胚层，并相应地在不同的孕周发育成为胎儿的各个组织及器官。外胚层主要分化成神经系统、皮肤表皮及毛发等；中胚层主要分化为肌肉、骨骼、血液系统、循环系统及泌尿生殖系统的大部分；内胚层主要分化为消化系统、呼吸系统的上皮组织及有关腺体等。停经5-8周，受精卵发育为胚胎，9周以后发育成为胎儿。胎盘等胎儿的附属物则一部分来自于胚泡细胞的分化，一部分来自母体细胞的分化，由此两部分形成。
精子和卵子结合有什么反应 精子和卵子结合有什么反应？精子与卵子结合的时候大多是没有过于明显的表现，而当受精卵成形的时候，孕妇就会有各种的症状。 大多数人在受精卵着床时并没有太明显的症状，也有些人有着床症状出现，小腹胀胀的，身体有些酸软无力。基础体温会下降，有些人会着床出血，敏感的人会觉得酸痛的感觉。另外，你应该了解一些有关怀孕过程的知识，在男子的精子射入女子的阴道后，因为宫颈管粘液呈碱性，有利于精子活动，所以精子很快即游向宫颈管。排卵后，由于卵巢雌激素的作用，宫颈口松弛，宫颈粘液稀薄，使精子易于穿透而进入宫腔。卵巢排卵后，卵泡液带着卵子缓慢流出，至腹腔内输卵管伞端附近，借助于输卵管的“拾卵”作用（伞端纤毛的大量摆动），卵子很快被吸入输卵管。由于在输卵管峡部一壶腹部连接点的肾上腺素能使肌肉括约的作用，卵细胞会在此处停留；由于壶腹部输卵管液流速慢，卵子在此处遇到精子时则可受精。 怀孕的时机，一般情况下是：如果你的月经周期规律的话，月经周期平均为28天。如果把月经来潮的日子（正常出血量）算作第一天，你一般会在下次月经来潮前两周左右排卵。在此以月经周期30天为例：第1天（月经来潮）第15-19天（排卵）第30天（下次月经来潮前一天）算出排卵的日子你就可以有计划地在排卵前后同房，受孕的几率就会很大，根据你的情况来看受孕的几率在90%以上。判断是否怀孕最直接有效的方法是用早孕试纸按照说明检查即可，也可以再来了解一些怀孕自身感觉的问题，通常情况下首先体温会升高，基础体温是指睡眠6小时以上，醒来不动，不吃东西，安静状态下测出的体温，也是用来判断怀孕的一个指标。如月经到期未来潮，体温升高后不再下降，并保持在18天以上，这时表示已经怀孕。 怀孕初期，许多孕妇有尿频的情形，有的每小时一次，这是增大的子宫压迫膀胱引起的。在怀孕3个月后，子宫长大并超出骨盆，症状会自然消失然后是早孕反应，月经过期不久的时候(2个星期左右)就开始发生胃口的改变。常发生在早晨起床后，有恶心、反酸、食欲不振、挑食等现象。有些人简直不想吃甚至要呕吐，有些人很想吃些酸味的东西。这些症状称为早孕反应，一般经过半个月至一个月，会自然消失。另外乳房发生变化，怀孕后，在雌激素和孕激素的共同刺激下，于第8周起，乳房逐渐长大，乳头和乳晕部颜色加深,乳头周围有深褐色结节等现象,12周以后还会有少许清水样乳汁分泌。还有一个现象是大家都知道的就是停经！ 怀孕是有很多东西都要知道，不要随随便便就怀上了，这样对你对宝宝都不好。在怀孕之前我们应该了解以上的知识，这样才能轻松自如面对怀孕。
精子和卵子有个体特征吗？ 在现在的生命科学研究中，据我所看到的资料和我所掌握的知识看，这一种学说认为：人的精子和卵子是一些在一个人的睾丸（或卵巢）中具有共性而无个性的个体（或者说在一次的可输出期里是这样）。 在这种假设中就出现了这样的结果：即在数亿个精子向同一个卵子发动进攻的时候，他们并没有任何的个体差异，谁进去都一样。因为大家都一样，所以数亿个精子就是为了同一个目标（受精，而且只能有一个成功）前赴后继，视死如归地向卵子发动进攻，当大多数精子为了创造一个受精的良好环境而牺牲的时候，大家拱托的一个精子终于获得成功，钻进了卵子，一个新的生命诞生了。 这样的结果符合实际的过程吗？我总觉得有些问题。首先，在人类的社会里，一群人要为了一个人的成功而视死如归的现象是难得一见的。大家为了一点小事尚且尔虞我诈，互相倾轧，你死我活，不要说为了生死存亡的终极大事，还能够把生的机会留给别人，把死的结果送给自己了。所以很难想象，从新生命的开始阶段，精子之间还能够有如此的大度。研究表明生命从基因开始就是自私的，精子和卵子不过是基因的产物，他们怎么可能不是自私的呢？所以我更愿意想象在精子进入阴道以后，条件一旦适宜，数亿精子之间的生死大战就开始了，顷刻之间死者为生者铺就了一条通向希望的路。 其次在人的社会里，每一个人都有自己的个体特征，这个情况
是从受精卵就开始出现的。对于人的社会来说，这个个体人的个体特征也是从一开始就予以承认。那么，我们是否也应该考虑一下，人的个体特征从什么时候开始的，精子和卵子是否也存在个体的特征，是不是每一个精子（或卵子）都具有自己的特点，而且这种特点是造成个体人的个体特征的唯一来源。这样一说就出现了以下的情况：对于一个卵子来说，在一次受精的机会里，数亿个精子都有可能成为候选者，也都有成功的可能，也就是说这个卵子有可能变出数亿个人的个体特征。而最后形成的那一个人是数亿个精子你死我活拼斗的结果。 再次，任何一个生命体内都存有三种意识，现代科学只承认人的显意识，而我在N学中早已论述了三种意识（显意识、潜意识和氨基酸意识）的存在，后两种意识在生命之初的作用是非常之大的，科学不能承认这两种意识的存在，所以也就无从研究他们在生命的开始阶段的作用。这是科学的一大谬误。因为是存在，所以即使在没有能力去说明的时候也要去充分的想象。没有想象就不可能引出真相。我认为潜意识和氨基酸意识在个体生命诞生之初是积极发挥作用的，而且这个作用是不可替代的，他们也可能在性交中就开始了一种从谈恋爱到结婚产子的过程，这个过程不是随意的，是精子和卵子有意识选择和结合的。 基于上述三个原因，我们是否可以重新想象一下生命的生长过程呢（不单指人）？ 在一个生命体内，卵巢和睾丸是两个创造后代的地方。这个地方有一个设计室，他具有独立的意识又可以接受来自人体的各种信
解析从受精到着床全过程（图片来源：家庭医生在线） 精子在女性生殖系统各环节存活的时间由于女性的排卵期各不相同，而性交时间又不一定，这就要求精子必须等待卵子的时间，以增加相遇的机会。所以精子在女性生殖道内生存的时间长短与生育有重要关系。 1、精子在女性生殖道内存留时间：阴道酸性分泌液平常为pH3.5～4。虽然理论上只要有一个活的精子就可以受精，但实际上在阴道的酸性环境下，大部分精子进入阴道没多久就死光了，只有在一定量精液的缓冲下，才有可能使极少数生命力强的精子存活的时间得以延长，获得进入子宫和受精的机会。如果没有大量精子的牺牲，如果没有一定量的精液缓冲改善阴道里的酸碱环境，单独一个精子或极少量的几个精子在阴道酸性环境里是不可能生存下来并受精的。一般情况下，精子在阴道内的存活时间是：性交之后2小时，90%死亡;36小时，连死的也看不见了。在孕妇的阴道内，酸度越强精子死亡越快。 2、精子在宫颈处的存留时间：宫颈粘液酸碱度的变化，对精子的穿入有很大影响。pH 小于6.5时，精子停止活动，pH7时，有轻度穿入能力，pH7.5时，穿入能力正常，pH8。2时穿入能力更强。在宫颈外口处有许多粘液阻塞，导致许多精子不能穿入，死在外边。宫颈粘液在月经刚过时，稠厚而韧性大;在接近排卵期时，因血液中雌性激素增加，粘液变多，变清，抽丝度增加;在排卵期时，粘液量更多，变清，外流，精子易于穿入。精子穿透宫颈粘液，是依靠酶的水解作用。胰蛋白本科糜蛋白酶和透明质酸酶能水解宫颈粘液，降低粘度，丧失粘丝形成，而有利于精子通过。一般情况下，精子在宫颈处的存活时间是：在宫颈内，性交后15分钟，就能在宫颈粘液中发现精子;一个小时后，精子进入内口;在宫腔内，性交后1小时宫腔内即有精子，6小时后，全是活动精子，12小时后5/6的精子仍存活，36小时后1/4的精子仍存活，三天之后，就没有活的了。但有时有个别的精子存活时间则特别长。
精子与卵细胞的产生和受精及减数分裂的意义 目标导航 1.在复习有丝分裂遗传物质变化的基础上，归纳减数分裂中遗传物质的数目变化规律。2.结合教材图文，通过列表比较精子和卵细胞形成过程的异同。3.概述受精作用的过程和减数分裂的意义。 一、精子与卵细胞的产生 1．精子的产生 在雄性性腺(睾丸)中有精原细胞，它们的染色体数目与一般的体细胞相同。它们中的一部分经过染色体复制，成为初级精母细胞(2n)，该细胞通过减数第一次分裂产生两个次级精母细胞(n)，再通过减数第二次分裂产生四个精细胞(n)，再经过一系列的形态变化，形成四个精子(n)。 2．卵细胞的产生 在雌性性腺(卵巢)中有卵原细胞，它们的染色体数目与一般的体细胞相同。它们中的一部分经过染色体复制，成为初级卵母细胞(2n)，该细胞通过减数第一次分裂产生一个较大的次级卵母细胞(n)和一个较小的第一极体(n)。次级卵母细胞再通过减数第二次分裂产生一个大的卵细胞(n)和一个小的第二极体(n)；第一极体通过减数第二次分裂产生两个等大的第二极体(n)。 二、受精作用和减数分裂的意义 1．受精作用 (1)概念：是指精子和卵细胞结合形成受精卵的过程。 (2)实质：精核和卵核融合在一起。 (3)结果：受精卵中的染色体数目又恢复到原来体细胞的染色体数目(2n)，其中，一半的染色体来自精子(父方)，另一半的染色体来自卵细胞(母方)。 2．减数分裂的意义 (1)通过减数分裂和受精作用，保持了生物在不同世代间的染色体数目和遗传性状的相对稳定。 (2)减数分裂为生物的变异提供了重要的物质基础，有利于生物对环境的适应和进化。 判断正误：
(1) 卵细胞的形成场所是卵巢。( ) (2) 初级卵母细胞、次级卵母细胞和极体的分裂都是不均等的。( ) (3) 1个卵原细胞只形成1个卵细胞。( ) (4) 卵细胞和精子的形成过程都需要变形。( ) (5) 卵细胞与精子形成过程的最大区别在于初级卵母细胞和次级卵母细胞的分裂是不均等的。( ) (6)一个精原细胞和一个卵原细胞经过减数分裂均形成四个配子。( ) 答案(1)√(2)×(3)√(4)×(5)√(6)× 一、精子和卵细胞的产生 1．精子与卵细胞形成过程比较 比较项目精子卵细胞 形成部位动物睾丸、植物花药动物卵巢、植物胚囊原始生殖细胞精原细胞(或小孢子母细胞) 卵原细胞(或大孢子母细胞) 细胞质的分裂与分配情况两次分裂都均等只有减数第二次分裂中第一极体均等分裂，其他分裂皆不均 等 续表 分裂结果1个精原细胞形成4个精细胞(生殖细 胞) 1个卵原细胞形成1个卵细胞(生殖细 胞)＋3个极体(消失) 是否变形4个精细胞变形生成4个精子不需变形 相同点①染色体的行为和数目变化的过程是一样的，表现在：a.染色体都是在减Ⅰ前的间期完成复制；b.减Ⅰ过程都发生同源染色体配对形成四分体、同源染色体分离；c.减Ⅱ过程都有着丝粒的分裂，姐妹染色单体的分开。②产生的子细胞数目都是4个，且细胞中染色体数目减半 (1)据配对现象判断：细胞中有染色体两两配对现象时，说明细胞中一定含同源染色体。 (2)据染色体数目判断：当正常细胞中染色体数目为奇数时，说明细胞中无同源染色体。 (3)据染色体的形态和大小判断：一个细胞中的每条染色体在该细胞中均有一条形态、大小与之相同的染色体时，说明细胞中可能有同源染色体。
3.1 体内受精和早期胚胎发育 第一课时 【教材分析】 1.教学内容分析 《体内受精和早期胚胎发育》一节的主要内容包括精子和卵子的发生、受精（准备阶段1——精子获能，准备阶段2——卵子的准备，受精阶段）、胚胎发育等三部分内容，本节是第一课时。 “科技探索之路”的内容通过对胚胎工程的建立历史的介绍，帮助学生建立科学、技术、社会相辅相成，协同发展的认识。 关于“精子和卵子的发生”部分的内容，这是受精作用和早期胚胎发育完成的基础。由于在必修二第2章第1节中，学生已比较详细的学习过减数分裂，所以教材此处的内容明显侧重于精、卵子发生的场所、形态、功能等变化的介绍，并通过“讨论”部分的设问帮助学生理解“排卵”等重要概念。 2.课程标准要求 本模块以专题的形式着重介绍现代生物科学和技术中一些重要领域的研究热点、发展趋势与应用前景，以开拓学生视野，增强科技意识，由于本模块所涉及的领域进展迅速，教师要积极引导和组织学生查阅有关资料，练习撰写专题综述报告，并组织开展口头交流、辩论等活动。 【教学目标】 1.知识目标 能简述哺乳动物的精子和卵子的发生过程和特点。 能举例说明精子与卵子发生的异同。 2.能力目标 在知识学习的过程中，学会整合提取文本重要信息，构建流程图的能力。 3.情感、态度、价值观目标
认同生物结构与功能相适应的观点。 【教学重点】 哺乳动物精子和卵子的发生。 【教学难点】 哺乳动物精子和卵子发生过程的异同。 【教学策略】 借助PPT，通过图片辅助，设问导入的方式，引出胚胎工程的概念。然后按照教材的思路，首先大体复习必修二第二章第一节“减数分裂”内容，然后通过设置相关问题，引导学生自主阅读、思考，提取信息；最后通过老师辅助梳理完成精子、卵子发生过程的教学。【教学过程】
精子与卵子的爱情故事 在我们的邻国日本，学者们用非常生动有趣的 来描述精卵结合的传奇，使人们能更加形象地了解整个生命起源的过程。 妊娠是如何形成的？为什么多数妊娠都能顺利进行，而有的妊娠在刚开始时就失败了？ 生命的起源，有多少不为我们所知的秘密？ 就让我们来看一看日本学者笔下的“精、卵恋爱故事”吧。 当卵子和精子在特定的时间内相会时，妊娠就开始了。几十万个卵子和几亿个精子中仅仅各有一个被选中，这是命运安排的恋爱。我们先来介绍一下“受精”的故事。 延伸阅读：精子与卵子的趣味对话壮烈的细胞：精子团队精神 从排卵、射精到受精 女性是带着卵子出生的 女性的体内共有两个卵巢，左右各有一个，卵巢内有卵细胞（装卵子的口袋）。令人惊奇的是，卵巢在胎儿期就已经存在了，那里面有700万的原始卵细胞。这个数量，在以后的岁月里会慢慢减少，出生的时候减少到200万，到了青春期就只有50万。 在卵细胞中有卵子，和包围着卵子的其他细胞。在女性出生以前，卵子生长在温暖的卵细胞中，沉着而安然地睡着，将来，“选择某个月，成为某人的新娘”，就这样一直期待着这一天。 一个月只有一次，从几十万的数目中脱颖而出。那么首先，我们先来看一下她的诞生。 一月一次的排卵中，卵子产生了 女性的体内，一旦到了青春期以后，一个月一次，不可思议的事情就发生了。几十万的卵细胞中，最终只有一个卵细胞能发展成熟。是哪一个卵细胞被选中，只有上帝才知道…… 这个月被选中的她，沐浴在卵细胞荷尔蒙中渐渐长大。等到她完全成熟的时候，就会大量生成黄体酮荷尔蒙，这样，一直包围、守护着新娘的卵细胞破裂了，她势如破竹般地从卵巢中飞跃出来，走上了和精子哥哥相会的旅程。这就是“排卵”。 成熟的卵子从卵巢中飞跃而出后，像喇叭一样大开着口的卵管入口就向她发出引诱："到这里来。"卵子很自然地流动着，进入了输卵管中。她在输卵管膨胀的部分等待着命运的相会。
高三生物——精子与卵细胞的产生和受精 知识梳理 1．精子、卵细胞的产生过程 (1)精子的产生：在雄性性腺(睾丸)中有精原细胞，它们的染色体数目与一般的体细胞相同。它们中的一部分经过染色体复制，成为初级精母细胞(2n)，该细胞通过减数第一次分裂产生两个次级精母细胞(n)，再通过减数第二次分裂产生四个精细胞(n)，再经过一系列的形态变化，形成四个精子(n)。 (2)卵细胞的产生：在雌性性腺(卵巢)中有卵原细胞，它们的染色体数目与一般的体细胞相同。它们中的一部分经过染色体复制，成为初级卵母细胞(2n)，该细胞通过减数第一次分裂产生一个较大的次级卵母细胞(n)和一个较小的第一极体(n)。次级卵母细胞(n)再经过减数第二次分裂产生一个大的卵细胞(n)和一个小的第二极体(n)；第一极体也分裂为两个第二极体。2．精子、卵细胞的产生过程不同 (1)卵细胞的产生经历了两次细胞质的不均等分裂。 (2)卵细胞可由减数分裂直接形成，不需要变形。 (3)一个卵原细胞只能产生一个卵细胞和三个极体，一个精原细胞能够产生四个精子。3．配子中染色体组合多样性的原因 (1)同源染色体的分离和非同源染色体的自由组合。 (2)同源染色体上非姐妹染色单体之间发生交叉互换。 4．受精(如图) 5．减数分裂的意义 (1)减数分裂和受精作用可保持生物染色体数目的恒定。 (2)减数分裂为生物的变异提供了可能，有利于生物对环境的适应和进化。 (1)减数分裂中若没有染色体片段的交换，则不利于生物对环境的适应和进化(×)
(2)减数分裂中发生均等分裂的细胞有可能是极体(√) (3)高等动物产生精子或卵细胞的过程中，只有非同源染色体上基因之间发生的自由组合属于基因重组(×) (4)正常情况下，在人的初级卵母细胞经减数分裂形成卵细胞的过程中，一个细胞中含有的X 染色体条数最多为4条(×) (5)若细胞中含有1 条Y染色体，则可确定该细胞为初级精母细胞(×) (6)精子和卵细胞的相互识别是通过细胞的直接接触完成的(√) (7)受精卵中的染色体和遗传物质均有一半来自父方，一半来自母方(×) (8)受精作用实现了基因重组，造成有性生殖后代的多样性(×) (9)受精的实质是精子进入卵细胞中(×) 1．减数分裂过程中的相关曲线图与柱形图(以精子形成为例) (1)甲为精原细胞；乙为初级精母细胞；丙、丁为次级精母细胞；戊为精细胞。 (2)染色体的数目变化及原因 ①减数第一次分裂末期，同源染色体分开平均进入两个子细胞，染色体数目减半。 ②减数第二次分裂后期，着丝粒分裂，染色体数目加倍到体细胞水平。 ③减数第二次分裂末期，细胞一分为二，染色体数目减半。 (3)核DNA数目变化及原因 ①减数第一次分裂前的间期，DNA复制，核DNA数目加倍。 ②减数第一次分裂末期，细胞一分为二，核DNA数目减半。 ③减数第二次分裂末期，细胞一分为二，核DNA数目再减半。 (4)染色单体的数目变化及原因