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PubMed2004

Optimal conditions for successful in vitro fertilization and subsequent embryonic development in Sprague-Dawley rats.

The present study was conducted to determine the optimal conditions for successful in vitro fertilization (IVF) in Sprague-Dawley (SD) rats. The IVF of oocytes from SD and Wistar rats was compared in different fertilization media (mR1ECM, IVF-20, and modified Krebs-Ringer bicarbonate solution [mKRB]), and IVF conditions were then optimized for oocytes of the SD strain. Results showed that in mR1ECM medium, fertilization rates were markedly lower in SD rats (15%) than in the Wistar strain (73%), although this response was significantly improved by increasing the NaCl concentration. In addition, fertilization rates in SD rats were higher in modified IVF-20 (73%) than in IVF-20 (18%) and mKRB (53%). In contrast, fertilization rates in Wistar rats were higher in IVF-20 and modified IVF-20 than in mKRB (78%, 74%, and 36%, respectively). Further investigation concerning the effects of the NaCl supplementation (10- 40 mM) in IVF-20 on the fertilization of oocytes in the SD strain indicated that significantly higher percentages of oocytes were fertilized in IVF-20 supplemented with 30 mM NaCl (66%) and developed to the blastocyst stage (47%) in vitro. After transfer, embryos derived from this IVF system developed to term at a percentage comparable to that of in vivo-fertilized controls. In conclusion, differences exist in optimal IVF conditions between rat strains, and a modified culture medium has been successfully developed for assessment of the developmental competence of oocytes in SD rats.

Animals↗
PubMed2026

Phenotyping of post-fertilization sperm mitophagy determinants discovered in a mammalian gamete-based cell-free system.

The targeted, substrate-specific degradation of paternal mitochondria inside the zygote, known as post-fertilization sperm mitophagy, is a crucial and evolutionarily conserved early embryonic event. It ensures the exclusive maternal inheritance of the mitochondrial genome. Post-fertilization sperm mitophagy was initially thought to only be achieved via the ubiquitin-proteasome system. Until pro-autophagic receptor proteins such as SQSTM1, GABARAP, as well as the proteasome-interacting ubiquitinated protein dislocase VCP, were identified as contributors to the degradation of the sperm mitochondria early after mammalian fertilization. This synergy of proteasomal and autophagic pathways ensures a timely degradation of sperm mitochondria shortly after fertilization. The discovery of these autophagic receptors lead researchers to believe there might be other autophagic receptors and determinants necessary for proper post-fertilization sperm mitophagy. Based on the established inventory of proteins from mass spectrometry trials of boar spermatozoa exposed to porcine oocyte extracts in an intra-specific porcine cell-free system (CFS), five candidate mitophagy determinants were further investigated in this study, namely LACTB, PRDX3, PSMA8, TOMM34, and FUNDC1. These proteins of interest were studied and validated by using in vitro fertilization (IVF) protocols, cell imaging of spermatids, spermatozoa, oocytes and zygotes, protein interactome analysis, and the porcine CFS. The proteins PSMA8 and TOMM34 behaved in accordance with our proteomic study predictions. The PSMA8 labeling increased after exposure to CFS; in agreement with the classification PSMA8 was given from the mass spectrometry findings. TOMM34 underwent a visible decrease in labeling after exposure to CFS, which also agreed with its proteomic classification; this labeling persisted in IVF zygotes. Except for LACTB, the examined proteins showed mutual interactions as well as interactions with previously identified sperm mitophagy factors in the STRING interactome analysis. Results from this study validate the novel porcine CFS as a valuable tool for the exploration of early fertilization events at a molecular level. Future phenotyping and functional studies using porcine CFS will advance the understanding of mitochondrial inheritance and zygotic development and potentially shed light on the origins of certain mitochondrial diseases arising from the failure of post-fertilization sperm mitophagy.

Animals↗
PubMed1983

Relationship between semen characteristics and fertility in electroejaculated mice.

Ejaculates were obtained from C57BL mice by applying two successive series of electrical stimuli which were delivered via a bipolar rectal probe. The ejaculates thus collected contained fertile spermatozoa as indicated by results from in-vitro fertilization. Once separated from the seminal plasma, ejaculated spermatozoa possessed the same in-vitro fertilization rate as epididymal sperm. Ejaculates were analysed for coagulum weight, ejaculate volume, sperm count, sperm motility, acid phosphatase content and fructose content. Significant differences were present between several of these values for fertile and infertile mice, and values were therefore empirically assigned to represent minimal amounts for 'normal' fertility (1.5 microliters ejaculate volume; 10.2 mg coagulum weight; 2.5 x 10(6) spermatozoa/ml; 2.3 x 10(3) motile spermatozoa/ejaculate). One half of the fertile animals had no deficiencies in any of the characteristics measured, whereas 97% of the infertile animals had at least one deficiency. No fertile male had more than 2 deficiencies. These data show that the characteristics of mouse semen obtained by the present method of electroejaculation are related to the fertility status of the animal.

Animals↗
PubMed1990

Morphology and proportion of inner cell mass of bovine blastocysts fertilized in vitro and in vivo.

The morphology and proportion of inner cell mass (ICM) of bovine blastocysts cultured in vitro or in vivo in rabbit oviducts after in-vitro fertilization of in-vitro matured follicular oocytes were compared with those of blastocysts fertilized in vivo by a differential fluorochrome staining technique. The delineation of each ICM cell was improved by the transfer of embryos derived from in-vitro fertilization to a rabbit oviduct although the cell-cell contacts of ICM cells were not as tight as those from in-vivo fertilization. The proportions (15.8 and 14.9%) of ICM in blastocysts cultured in vitro at early and expanded stages were significantly lower than those cultured in rabbit oviducts after in-vitro fertilization and fertilized in vivo. These results show that the transfer of bovine embryos derived from in-vitro fertilization to the rabbit oviduct increased the proliferation of ICM cells to the level of embryos fertilized in vivo although the cell-cell contact of ICM cell is not improved by the process.

Animals↗
PubMed1995

The effects of HIV and AIDS on fertility in East and Central Africa.

Concern has been expressed about the fertility of people infected with HIV: the worry has been that on learning of their condition, HIV-affected individuals may attempt to accomplish unmet reproductive goals knowing that they will not live a normal life span. This article addresses the potential effects of AIDS on fertility and reproductive decisions in East and Central Africa. The problem is seen in terms of a tightly knit continuum of biological, epidemiologic and cultural contexts, and the prevailing conditions of response to the epidemic. AIDS can influence fertility among individuals and groups regardless of any awareness of serostatus by increasing death rates among reproductive populations, and damaging the physical capacities of infected men and women to reproduce. In much of the region, high prevalence of STDs may simultaneously impair the fertility of men and women and increase their risk of contracting HIV. These biological conditions are compounded among those for whom fertility is a highly valued marker of adult status, where the social and economic marginality of young women contributes to reliance on commercialized sex, where the mobility of young men leads to instability in sexual partnerships and frequent partner change, or where women lack the ability to negotiate their fertility with spouses. It appears that even focused programs of testing and counselling with HIV-positive women in Europe and in Africa have not motivated a significant change in reproductive action. Were there a demonstrable effect of counselling on the fertility choices of infected persons, there are numerous practical limitations on the role that interventions can play in affecting the fertility of HIV-positive people.

Adult↗
PubMed1988

[Fertility life tables].

"Three tables for measuring human fertility are presented. The first, the Parity-Fertility-Life-Table, includes the intensity of fertility only. The second table, the Marriage-Duration-Fertility-Life-Table, bases on the Parity-Fertility-Life-Table and measures the tempo of fertility altogether. The third table, the Birth-Interval-Fertility-Life-Table, completes the Marriage-Duration-Fertility-Life-Table in considering the point of time, at which the last parity is reached." The methods are illustrated using official data for the Federal Republic of Germany. (SUMMARY IN ENG)

Birth Intervals↗
PubMed1990

Duration of residence in the United States and the fertility of U.S. immigrants.

"This paper analyzes census data on the fertility of U.S. immigrants to study trends in fertility after migration. The results showed that immigrant fertility may rise after arrival in the new country perhaps because immigrants are making up for births or marriages that may have been postponed due to the move. After a period of time, the fertility of immigrants may fall and as immigrants become more assimilated to the new country their fertility may come to be similar to cohorts of longer duration. These relationships were examined in a multivariate context so that variations between groups in socioeconomic status, fertility in the country of origin, age and marital status could be controlled. Relationships were studied for all U.S. immigrants as well as for subgroups defined by country or region of origin. The results indicate that simple measures of immigrant fertility that do not consider duration of residence are likely to be misleading if used to draw conclusions about the fertility impacts of immigration and advisable policy interventions."

Acculturation↗
PubMedDate not supplied

Mammalian fertilization, IVF, ICSI: physiological/molecular parameters, clinical application.

Fertilization is associated with several phenomena: rearrangement of euplastic cytoskeleton, intra-cellular communication, cellular polarity, and the release of a variety of complex systems. Several criteria are used to score fertilization. On the day after fertilization, oocytes are cleaned of cumulus and examined for presence of 2 pronuclei and any possible cytological anomalies. Function tests to evaluate fertilization include SPA, ZBA, SCSA, AAA acrosome reaction and fluorescent probes. Fertilization failure, silent polyspermy, aster arrest, mitotic arrest, aster growth defect, or immuno-logical mechanisms cause infertility. Sperm-induced oocyte activation may be due to ligand-recep-tor-mediated interaction or a soluble sperm-derived factor that enters the oocyte at the time of fusion. Any abnormalities in transcription, translation, or any other significant molecular process responsible for producing the oocyte-activating ligand/effector molecule during spermatogenesis and/or spermatogenesis will ultimately cause fertilization failure. The centrosome is paternally derived. During the time course of fertilization the sperm centrosome is orchestrating producer mobilization, syngamy and, ultimately, early cleavage. Vesicle-associated membrane protein(VAMP) is typically lost at cell surface during sperm penetration. Understanding cytoskeletal motility during fertilization requires sophisticated digital imaging including conventional epifluorescence microscopy, laser scanning confocal microscopy and time lapse video microscopy. Clinical application of the recent finding is discussed with emphasis on timing of coitus or insemination, to coincide with time of monitored ovulation. Future research directions are outlined.

Animals↗
PubMed1990

The end of an affair? Geography and fertility in late post-transitional societies.

A common theme in the writings of population geographers with a fertility interest has been a concern with the convergence of interregional fertility differentials. It is now clear, however, that the widespread achievement in western societies of below-replacement fertility has resulted in a dramatic diminution of most forms of differential fertility, whether sectoral or spatial. The question of "what remains for the spatial analyst working in the traditional ecological mode?" must therefore be asked. An analysis of small-area fertility differentials in NSW in 1986 suggests (a) that most of the variability in local marital and total fertility is not statistically significant, and (b) that even if this problem is ignored, traditional ecological analysis has only trivial 'explanatory' power. While complete spatial uniformity is unlikely ever to be achieved, it is argued that the intrasocietal convergence of reproductive norms and behavior has proceeded so far that conventional geographic approaches to the analysis of fertility are unlikely any longer to be, if they ever were, fruitful

Australia↗
PubMed1993

Changes in the determinants of fertility in Korea: analyses of pregnancy intervals and outcomes.

Korea completed the whole process of what is called the demographic transition to a low fertility and mortality level with the successful implementation of the national family planning program in 1962, and this has been accompanied by rapid socioeconomic development. Most of the fertility decline was due to a rising age at marriage and to lower marital fertility. The national family planning program, combined with the widespread practice of induced abortion, has placed an important role in reducing marital fertility, particularly among older women. This paper aims, therefore, to examine the determinants of fertility and their changes over time in an effort to suggest future population policy directions for Korea. The analysis is divided into 2 parts-estimation of pregnancy intervals by applying the proportional hazards model, and estimation of the determinants of fertility by adopting the logistic regression model to find out whether a pregnancy terminates in a live birth or in an abortion. In both analyses, the sex was included as the main explanatory variable. A woman's education has been shown to have a significant effect on delaying the timing or on the wife's age at first pregnancy, but its effect on the pace of subsequent pregnancies is much smaller and often positive. On the other hand, the woman's education has a consistently positive effect on the probability of a pregnancy ending in an abortion although the effect shows a steady decline over time. Form first parity, the sex composition of previous children stands out consistently as the most important factor in deciding both the pace of pregnancy and its outcome. The pregnancy risks of the women with sons are reduced by almost 50% at the second and third parities. The probability of a pregnancy ending in an abortion also increases substantially when parents already have a son. The decline of the desired family size but the sustained strong son preference has made the sex of children a more important factor in the determination of Korean fertility. The woman's education, on the other hand, has become a less important factor.

Abortion, Induced↗
PubMed1978

Declining world fertility: trends, causes, implications.

This Bulletin examines the evidence that the world's fertility has declined in recent years, the factors that appear to have accounted for the decline, and the implications for fertility and population growth rates to the end of the century. On the basis of a compilation of estimates available for all nations of the world, the authors derive estimates which indicate that the world's total fertility rate dropped from 4.6 to 4.1 births per woman between 1968 and 1975, thanks largely to an earlier and more rapid and universal decline in the fertility of less developed countries (LDCs) than had been anticipated. Statistical analysis of available data suggests that the socioeconomic progress made by LDCs in this period was not great enough to account for more than a proportion of the fertility decline and that organized family planning programs were a major contributing factor. The authors' projections, which are compared to similar projections from the World Bank, the United Nations, and the U.S. Bureau of the Census, indicate that, by the year 2000, less than 1/5 of the world's population will be in the "red danger" circle of explosive population growth (2.1% or more annually); most LDCs will be in a phase of fertility decline; and many of them -- along with most now developed countries -- will be at or near replacement level of fertility. The authors warn that "our optimistic prediction is premised upon a big IF -- if (organized) family planning (in LDCs) continues. It remains imperative that all of the developed nations of the world continue their contribution to this program undiminished."

Africa↗
PubMed1988

Has Thailand's fertility decline stalled?

Thailand is 1 of the third world countries in which a very substantial fertility decline has occurred during the last 2 decades. However, there has been some recent concern, based on fertility rates derived from 3 national contraceptive prevalence surveys conducted in 1978/1979, 1981, and 1984, that the fertility decline may have lost momentum at a level well above replacement fertility. New evidence now available from a more recent national survey which permits calculation of retrospective fertility trends, in combination with those from registration data, clearly contradicts the suggestion of a fall in the fertility decline. Moreover, because expected family size remains low among women currently starting their reproductive careers and evidence shows that the preferred number of children has fallen more or less steadily, low fertility may be expected to be a feature of the Thai population for some time to come.

Asia↗
PubMed1996

Persistence of the developmental block of in vitro fertilized domestic cat embryos to temporal variations in culture conditions.

A series of studies examined the influence and temporal interaction of energy substrate, media complexity, and tissue co-culture on the development of in vitro fertilized cat embryos and the persistence of the morula-to-blastocyst developmental block. In study I, oocytes were fertilized and cultured for 144 hr in a simple culture medium (modified Krebs Ringer bicarbonate; mKrb), containing either glucose or glutamine, or cultured in mKrb w/ glutamine for the initial 72 hr with transfer to mKrb w/ glucose for the final 72 hr. Fertilization rate, percent development to morulae, and cell number per embryo were similar (P > 0.05) between treatments and blastocyst formation was universally low (< 10%). In Study II, oocytes were fertilized and cultured in either mKrb (w/glucose or glutamine) or in a complex medium, Ham's F10 (w/ 10% fetal bovine serum [FBS]). After 72 hr of initial culture, embryos in mKrb were transferred into Ham's F10. Fertilization rate was lower (P < 0.01) in Ham's F10 but embryo development to the morulae stage and cell number per embryo were comparable (P > 0.05) for all treatments. A higher percentage of blastocysts and morulae becoming blastocysts were observed after initial culture in mKrb w/ glutamine than after initial culture in mKrb w/ glucose. In Study III, oocytes were fertilized and cultured initially in mKrb (w/ glutamine), and then switched to either Ham's F10 or cat oviductal cell monolayers (in Ham's F10). Additional embryos were cultured exclusively in Ham's F10 or on cat oviductal cell monolayers. Fertilization rates were lower (P < 0.05) on oviductal cells but cell number per embryo was similar (P > 0.05) in all treatments. Blastocyst formation was lower (P < 0.05) on oviductal cells than in mKrb-Ham's F10 treatment and was < 20% in all treatments. In summary, while in vitro fertilization-derived cat embryos develop to morulae under a variety of culture conditions, the morula-to-blastocyst developmental block was minimally responsive to alterations in energy substrate and medium complexity or fluctuations in their temporal availability. In addition, oviductal cell culture, alone or in combination with other culture variations, was ineffective in overcoming the developmental block.

Animals↗
PubMed1995

Protein tyrosine phosphorylation during sea urchin fertilization: microtubule dynamics require tyrosine kinase activity.

Protein tyrosine phosphorylation plays an important role in cell growth, mitosis, and tumorigenesis. It has also been implicated in meiotic maturation and fertilization. We have used anti-phosphotyrosine immunofluorescence and immunoblotting to identify sperm and egg proteins which are phosphorylated on tyrosine residues prior to and during sea urchin fertilization. On immunoblots of sperm proteins, the monoclonal anti-phosphotyrosine antibody detected three major proteins with molecular weights of 44, 82, and 100 kD, and six minor bands at 46, 48, 70, 76, 95, and 150 kD. These phosphotyrosyl proteins were localized to the sperm acrosomal and centriolar fossae. In contrast, staining was found globally in unfertilized eggs, and the antibody recognized two major egg phosphotyrosyl proteins of molecular weights 42 and 50 kD, and five minor bands at 40, 90, 116, 130, and 150 kD. While immunofluorescent staining remained throughout the fertilized egg cytoplasm, there were dynamic changes in the staining intensity of single bands. The 90 kD immunoreactive band increased in intensity, and the 40 and 42 kD bands disappeared by 15 min after fertilization. Loss of the 40 and 42 kD bands was due to dephosphorylation by okadaic acid-sensitive phosphatase(s). The 50 kD immunoreactive protein was unchanged up to the 8-cell stage and was still present in blastulae, indicating its importance throughout fertilization and early development. Alterations in the pattern of phosphotyrosine-containing proteins during fertilization did not depend on nascent proteins and could not be completely mimicked by increasing intracellular calcium, pH, and protein kinase C activity alone. Since changes in the fertilization pattern of phosphotyrosyl proteins occurred during formation of the sperm aster and mitotic spindle, we analyzed the role of protein tyrosine kinase activity in these processes using the tyrosine kinase specific inhibitor, erbstatin. Both the sperm aster and mitotic spindle were disrupted, indicating an involvement of tyrosine phosphorylation in these processes during interphase and mitosis. We conclude that the changes in phosphotyrosyl proteins play an important role in fertilization and early development of sea urchin eggs. Control of microtubule assembly into the sperm aster and mitotic spindle of the first cell cycle are examples of such roles.

Animals↗
PubMedDate not supplied

Correlation between human sperm swelling in hypoosmotic medium (hypoosmotic swelling test) and in vitro fertilization.

Human ejaculates (n = 83) were analyzed for standard sperm parameters (concentration, motility, and morphology), as well as for the ability of the spermatozoa to react (swell) in a hypoosmotic medium (Jeyendran et al, 1984). Subsequently, the fertilizing capacity of the spermatozoa was tested by their ability to fertilize human oocytes in vitro. Although the sperm concentration was adjusted for in vitro fertilization, no adjustments were made for sperm motility and morphology. Correlation of the in vitro fertilizing capacity of the spermatozoa with the hypoosmotic swelling test (r = 0.56) was much higher than with standard sperm parameters (r varied from -0.04 to 0.25). Complete overlap was noted with standard semen parameters whether the ejaculate did or did not fertilize oocytes and ranged from very low to very high values in both cases. By contrast, all the semen samples that fertilized oocytes showed a 60% or higher reaction in the hypoosmotic swelling test, whereas the majority of the "infertile" semen samples showed less than 60% swelling. It therefore appears that, under the conditions of our studies, the hypoosmotic swelling test is a more accurate predictor of successful in vitro fertilization outcome than the conventional semen parameters. A combination of all parameters, however, is likely to be most useful. The hypoosmotic swelling test is simple and economical, and it is recommended that this test be further scrutinized for its value as an additional tool in the assessment of the in vivo fertilizing capacity of ejaculated spermatozoa.

Cell Survival↗
PubMed1981

Inhibition of in vitro fertilization of mouse eggs: 3-quinuclidinyl benzilate specifically blocks penetration of zonae pellucidae by mouse spermatozoa.

The fertilization in vitro of mouse with intact zonae pellucidae by mouse cauda epididymal spermatozoa was inhibited in a concentration- dependent fashion by 3-quinuclidinyl benzilate (QNB), normally used as a specific antagonist for the muscarinic class of cholinergic receptors. Inhibition was observed with both cumulus-intact and cumulus-free preparations. QNB at 50 microM inhibited fertilization of cumulus-free eggs by greater than 90% but had no effect on the fertilization of zona-free eggs. At this concentrations, QNB had no adverse effect on sperm motility, nor did it prevent binding of spermatozoa to the zona pellucida. The inhibitory effects of QNB were fully reversible. QNB is therefore a useful specific inhibitor of zona penetration. Spermatozoa in the in vitro fertilization medium bound QNB with a concentration dependence which matched that of the inhibition of fertilization. This binding was saturable and corresponded to 700 pmole/10(7) cells with KD = 10 microM. The in vitro fertilization medium contains 2% (w/v) bovine serum albumin (BSA) which also binds QNB according to the mass action law. The large amount of QNB bound to sperm in this medium appears to be QNB binding to BSA adsorbed on the sperm cell surface: these spermatozoa bind QNB specifically in the absence of BSA with a saturable capacity of only 70 fmole/10(7) cells with KD = 5 nM. Calculation of the distribution of QNB between BSA binding sites and sperm surface binding sites in the in vitro fertilization medium indicates that the specific sperm sites become saturated with the same concentration dependence as inhibition of fertilization. However, the dissociation rate of QNB from sperm in both the presence and absence of BSA is too rapid to permit confirmation of these sites as the locus of the inhibitory effect; this locus remains to be clarified.

Animals↗
PubMed1988

Effects of cytochalasins B and D on the fertilization of zebrafish (Brachydanio) eggs.

The effects of selected concentrations of cytochalasins B (1-10 micrograms/ml; CB) and D (10, 50 micrograms/ml; CD) on the morphology and fertilization of zebra danio (Brachydanio) eggs were studied primarily with light and scanning electron microscopy. Eggs pretreated with either CB (10 micrograms/ml) or CD (10, 50 micrograms/ml) prepared in Fish Ringer's solution-0.5% DMSO showed a flattened shape, alterations in the form of surface microplicae and microvilli, and occasional spontaneous exocytosis of cortical granules. All eggs preincubated in either CB or CD were activated upon transfer to tap water, showing cortical granule exocytosis, elevation of the chorion, and formation of a fertilization cone. When eggs were pretreated for 5 minutes with 1-5 micrograms/ml CB or 10 micrograms/ml CD and inseminated, they incorporated the fertilizing sperm and typically developed to the two-cell stage. A single sperm cell attached to and fused with the sperm entry site microvilli but failed to enter the cytoplasm in eggs preincubated with 10 micrograms/ml CB. Eggs that were immersed continuously in either CB (10 micrograms/ml) or CD (50 micrograms/ml) 15 seconds after insemination also failed to incorporate the fertilizing sperm. Treatment of eggs after insemination with CD (10 micrograms/ml), however, did not prevent sperm cell incorporation or fertilization cone formation. Our drug data suggest the presence of actin-containing filaments in the danio egg before and following fertilization. These filaments appear to play a role in maintaining the shape of the egg cell and its surface specializations and in the incorporation of the fertilizing sperm. The fertilization cone appears to form independently of actin polymerization.

Actin Cytoskeleton↗
PubMed1988

Caffeine promotes in vitro fertilization of mouse ova within 15 minutes.

Epididymal sperm were collected from C57Bl6/J X DBA2/J (B6D2) males and allowed to capacitate for 2 hr. When cumulus-free oocytes were exposed to sperm for 15 min in either the presence (6.0 mM) or absence of caffeine, fertilization did not occur. However, when cumulus cells were left intact, 23% of oocytes were fertilized in caffeine-free medium and 62% in caffeine-containing medium. When cumulus-free oocytes were incubated with sperm for 30 min, none was fertilized in the absence of caffeine, but 33% were fertilized when 6.0 mM caffeine was present (P less than .02). These effects of caffeine were on the sperm, as sperm exposed to caffeine and then coincubated with oocytes for 15 min in essentially caffeine-free media fertilized a similar percent of oocytes (93%) as when sperm and oocytes were exposed to caffeine during the fertilization period (86%). When sperm were capacitated in caffeine-containing medium, the percentage of ova fertilized was similar to capacitation without caffeine. We conclude that both cumulus cells and caffeine speed up the fertilization process with mouse gametes and that the effect of caffeine is on the sperm, but not due to more rapid capacitation.

Animals↗