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PubMedDate not supplied

Examination of the binding ability of bovine spermatozoa to the zona pellucida as an indicator of fertility.

Despite the development of many new techniques, laboratory assays still do not predict male fertility accurately. To identify targets for laboratory assessment, we first need to determine which steps in fertilization are most often defective in subfertile males. We developed a competitive in vitro fertilization assay in which spermatozoa from 2 different males, stained with different lipophilic dyes, are incubated together with oocytes in a droplet. By exposing mixed spermatozoa to the same oocytes, this assay controls for many of the variables of in vitro fertilization and should allow identification of the most common faulty steps in fertilization. The relationship of zona-binding ability to fertility is controversial. Therefore, as a first step, we determined if zona pellucida-binding ability, measured by this competitive assay, was related to bovine spermatozoal fertility. Fertility data were collected from 2 groups of bulls by 2 means of evaluation, nonreturn to estrus rates postinsemination and competitive insemination. In the nonreturn to estrus study, semen samples from 15 bulls were effectively ranked by zona-binding ability, using pairwise competitive in vitro zona-binding assays (R(2) = 0.84). However, this ranking was not significantly correlated with nonreturn rates (r = -0.04). In the competitive insemination study, semen samples from 8 bulls were effectively ranked by pairwise comparison using the competitive zona-binding assay (R(2) = 0.67). Again, this ranking was not significantly correlated to the competitive insemination index calculated for these bulls (r = 0.29). In the third study, we tested 3 bulls to determine if in vivo zona binding, assessed by the number of accessory spermatozoa, was correlated with in vitro zona binding. The number of accessory spermatozoa on oocytes recovered from cows after mating was not correlated with in vitro competitive binding of the spermatozoa. In conclusion, in vitro competitive zona binding was not correlated with bovine fertility or binding of accessory spermatozoa to oocytes in vivo.

Animals↗
PubMed1986

Four themes in fertility research.

This study is concerned with four main themes that have been combined to describe U.S. fertility trends since 1920. These themes are identified as a time adjustment mechanism, income, the wife's labor force activities, and some intergenerational factor. "In order to obtain an unambiguous picture each theme will be represented by only one variable. After selecting the variables and estimating a model, an examination of the changing role these variables have had in explaining changes in fertility (the total fertility rate) throughout much of this century will be made. Finally, the implications these themes have for future fertility will be examined." The authors conclude that "in interpreting historical U.S. fertility rates, the results seem to indicate that much of the early decline in U.S. fertility was due to falling infant mortality. After the Second World War, fertility rose sharply as the age-structure variable declined and income rose. Eventually both women's labor force participation rates and the age-structure variable rose and, consequently, fertility fell." They also suggest that the age structure variable may cause a temporary upward swing in fertility in the near future.

Americas↗
PubMed1987

In Vitro Fertilization (Restriction) Act, 1987 (No. 27 of 1987), 23 April 1987.

This Act provides that a person may not carry out an in-vitro fertilization procedure except as part of one of three in-vitro fertilization programs operated by certain named institutions. The Act defines in-vitro fertilization procedure to mean any of the following: "a) the removal of a human ovum for the purpose of fertilization within or outside the body; b) storage of any such ovum prior to fertilization; c) the fertilization by artificial means of any such ovum within or outside the body; d) the culture or storage of a fertilized ovum outside the body; e) the transference of a fertilized or unfertilized ovum into the body." This summary takes account of an amendment introduced by the In Vitro Fertilization (Restriction) Act Amendment Act, 1987 (No. 83 of 1987), 27 November 1987.

Australia↗
PubMed1998

Measuring the impact of HIV on fertility in Africa.

OBJECTIVES: To review evidence for the impact of HIV on fertility from empirical sources pertaining to African populations and to discuss the implications for surveillance based on antenatal clinic populations. METHODS: The theoretical equivalence between the fertility rate ratio for HIV-positive to HIV-negative women and the relative odds of being infected for pregnant women compared with the general female population is demonstrated. This equivalence is used to compare fertility differentials measured in cohort studies with those calculated indirectly from antenatal clinic data. Data from case-control studies and theoretical predictions from a model of the proximate determinants of fertility and HIV incidence are used to obtain plausible explanations of the fertility differences. Estimates of population attributable change are made. RESULTS: Fertility of HIV-positive women is lower than that of HIV-negative women, in all but the youngest age-group, and the differential increases with women's age and epidemic duration. Selection for early start of sexual activity explains the reverse pattern at younger ages. Lower fertility amongst HIV-positive women causes a population attributable decline in total fertility of the order of 0.4% for each percentage point HIV prevalence in the general female population. CONCLUSIONS: In populations that do not use contraceptives, HIV-positive women have lower fertility principally as a result of foetal losses consequent to infection with HIV and coinfection with other sexually transmitted diseases; behavioural factors tend to enhance this differential. Other factors being equal, HIV prevalence estimates based on antenatal surveillance underestimate true prevalence in women in the childbearing years.

Adolescent↗
PubMed1996

Fertility patterns according to occupational grouping in Norway, 1989.

In the early 1990s, most pregnant women in Norway were in gainful employment. This led to increased interest in the possible consequences for reproductive health, and a growing concern for the need to accommodate the pregnancy. We have therefore investigated how accurately general fertility rates predict the number of pregnancies in the workforce. Fertility rates (FR) among employed women and standardized fertility ratios (SFR) in occupational groups were estimated on the basis of information from the Labour Market Statistics and the national survey "Pregnancy and Work", Norway, 1989. The fertility rate among employed women was 17% higher than the general fertility rate. Two occupational groups had significantly different SFRs: technical/professional workers (SFR 118) and transport/communication workers (SFR 82). In addition, differences were found for parity-specific SFRs in administrative/executive work (SFR nullipara 80, SFR para 125) and service work (SFR nullipara 114, SFR para 80). We suggest that work status and occupation should be included among the variables registered in the Medical Birth Registry of Norway, in order to facilitate routine presentations of fertility rates and pregnancy outcomes for women in paid work. The results further indicate that work-specific conditions influence first-birth fertility. This should be explored in demographic studies of the relation between women's fertility and participation in paid work.

Adolescent↗
PubMed1998

The ecology of low natural fertility in Ladakh.

The existence of very low rates of fertility among non-contracepting human populations has intrigued researchers in demography and reproductive ecology. Long inter-birth intervals, driven primarily by the lactational amenorrhoea associated with breast-feeding, have been shown to be important determinants of low natural fertility in several populations. Other reports have suggested that sterility brought about by sexually transmitted diseases (STDs) might also explain low fertility in some populations, especially in Africa. This report presents an analysis of 1981 Indian census data that documents low natural fertility in Ladakh, a high-altitude region of the Himalaya in north India. In Ladakh, there is evidence for low rates of marriage among women that may be attributable to the practice of polyandry, but also high rates of primary and secondary sterility within marriage, resulting in low completed parities for post-reproductive age married women. Age-specific fertility rates derived from the number of current births are also unexpectedly low. Hypotheses to explain very low fertility in Ladakh are considered from among the likely proximate determinants and evaluated using two supplementary sources of information derived from fieldwork in Ladakh in the early 1990s. The most likely explanations for low marital fertility include sterility from STDs, high rates of fetal loss, and possibly nutritional contraints on ovarian hormone status.

Adolescent↗
PubMed1996

Modifications of the lectin binding pattern in the rat zona pellucida after in vivo fertilization.

The zona pellucida (ZP) is an extracellular matrix surrounding the mammalian oocyte. It is involved in the sperm-egg adhesion phenomenon, induces the acrosome reaction, and participates in the late blockage to polyspermy. Thus, during the process of fertilization the cortical reaction is induced and the biochemical and biological properties of the ZP are modified. Some of these changes have been suggested to prevent the polyspermy. However, the mechanisms behind most of these changes are not well understood. Carbohydrate residues of the ZP glycoproteins have been shown to play a key role in the early step of fertilization. In the present study, the changes produced in the terminal oligosaccharide sequences of the rat ZP glycoproteins after in vivo fertilization were investigated by means of lectin-gold cytochemistry. A comparative quantitative analysis of the density of labeling in the ZP before and after fertilization was carried out by automatic counting of gold particles. The ZP of fertilized and unfertilized eggs were labeled by a battery of lectins including PNA, LFA, MAA, AAA, DSA, RCA I, and WGA. For all lectin studied in both fertilized and unfertilized eggs the labeling was preferentially located in the inner region of the ZP. After fertilization, binding of PNA, LFA, MAA, AAA, and DSA decreased in both inner and outer regions of the ZP. Labeling of RCA I-binding sites only decreased in the inner ZP, whereas reactivity to WGA was increased in the inner ZP, whereas reactivity to WGA was increased in the inner area of the ZP. Digestion of the thin-sections with neuraminidase prior to labeling with WGA resulted in a decrease of labeling for WGA binding sites. However, the labeling density of WGA binding sites was similar in both unfertilized and fertilized eggs upon treatment with neuraminidase. The present results demonstrate that the oligosaccharide chains contained in the rat ZP are modified after fertilization of the oocyte. Cortical granules of the oocytes might be involved in these modifications by two mechanisms: 1) by hydrolysis of terminal carbohydrate residues of ZP glycoproteins by specific glycosidases contained in the granules; and 2) by addition of new glycoproteins to the ZP after the exocytosis of the cortical granules (cortical reaction).

Animals↗
PubMed2002

Egg-jelly structure promotes efficiency of internal fertilization in the newt, Cynops pyrrhogaster.

Egg-jelly is composed of a network of fibrous components and contains substances regulating the sperm-egg interaction. Many studies on the latter have been conducted, whereas the role of the egg-jelly structure in fertilization has not yet been fully assessed. In this study, we examined the fertilization efficiency in the presence and absence of the structure around the egg of the newt, Cynops pyrrhogaster, using a gelatin gel system. Although de-jellied eggs of C. pyrrhogaster can be fertilized with an adequate number of sperm, the fertilization rate was dramatically increased through the use of the gelatin gel. Sperm showed forward motility with straight morphology in the gel, whereas they swam in circles in solution. This result indicates that the gel structure is significant for sperm guidance to the egg surface, and its presence raises the fertilization efficiency in C. pyrrhogaster. When sperm were entangled in the gel structure, they were immediately folded and never showed any forward motility. Sperm with zigzag morphology were observed in the gelatin gel as well as in the egg-jelly, indicating the elimination of sperm by the gel structure. The effect of sperm elimination on successful fertilization was estimated using gelatin gels of different thickness. Though the variation did not affect the fertilization rate, the rate of normal development gradually increased in the thicker gels. This result indicates that sperm elimination in egg-jelly can function in the fertilization system. The roles of sperm guidance and sperm elimination under the physiological condition of internal fertilization of the newt are discussed.

Animals↗
PubMed1995

Intratesticular retention of sperm and premature decline in fertility in the domestic rooster, Gallus domesticus.

In domestic roosters, which were originally seasonal breeders and that are now kept under unnatural and unchanging conditions throughout the year, fertility peaks at 32 weeks of age (96%) but it subsequently declines rapidly to only 5% at 110 weeks despite the fact that roosters can live for about 10 years. Roosters exhibiting this low-fertility syndrome have reduced levels of spermatozoa in the ejaculate. Concomitantly, however, superabundant but apparently normal spermatozoa are found attached to Sertoli cells and, in addition, the seminiferous epithelium fails to show evidence of the regression of atrophy that characterizes both aging non-seasonal breeders and true seasonal breeders during non-reproductive periods. This syndrome of premature low fertility appears to stem from impaired spermiation with resultant retention of spermatozoa by Sertoli cells. To examine this problem, we compared intratesticular incorporation of 3H-thymidine between high-fertility (32-week-old) and low-fertility (82-week-old) roosters. Radioactivity associated with spermatozoa, 33 days post-injection, was almost 50% higher in the low-fertility roosters than in the high-fertility ones. By contrast, both groups showed similar characteristics with respect to a) intratesticular incorporation of 3H-thymidine, b) dynamics of spermatogenesis, c) intratesticular level of radioactivity just before the initiation of spermiation, and d) the duration of both spermatogenesis and the time required for sperm to pass through the genital tract. Our results confirm that intratesticular retention of sperm occurs in roosters with premature low-fertility syndrome and suggest new possibilities for the study of the complex relationship between Sertoli cells and spermatozoa and the effects of this relationship on fertility.

Animals↗
PubMed1991

Fertilizing capacity of epididymal and testicular spermatozoa microinjected under the zona pellucida of the mouse oocyte.

Mouse spermatozoa were obtained from the testis and caput, corpus, and cauda epididymis incubated for 2 h in capacitation medium and a single spermatozoon from the capacitated samples microinjected into the pervitelline space of mature mouse oocytes. Spermatozoa from the testis were unable to fertilize oocytes and few spermatozoa from the caput were capable of fertilization (0-7% depending on the method of preparation). Similar fertilization rates (30-45%) were obtained with spermatozoa with forward progressive motility from the proximal and distal corpus and the cauda epididymis, but those that were vibratory or with local circular motility had significantly reduced fertilizing capacity (6-10%). The capacity of spermatozoa from the different regions of the testis and epididymis to bind to zona-free oocytes followed the same pattern as fertilization rate after microinjection. There was a progressive increase in acrosome reactions after 2 h incubation in capacitation medium in samples obtained from the testis to the cauda epididymis. Maturation of the capacity to bind to the perivitelline membrane and to develop forward progressive motility, rather than the capacity to acrosome react, appears to govern the fertilization of oocytes in which the zona has been bypassed by microinjection. These characteristics are obtained in the proximal segment of the corpus. However, there was evidence that the embryo developmental capacity of oocytes fertilized by spermatozoa from the higher segments of the epididymis is reduced, particularly in oocytes fertilized by caput spermatozoa. These observations suggest that sperm microinjection may have only a limited benefit for improving fertilization rates for men with high epididymal obstructive azoospermia.

Acrosome↗
PubMed1991

Comparison of sperm binding potential of uninseminated, inseminated-unfertilized, and fertilized-noncleaved human oocytes under hemizona assay conditions.

In this study, human oocytes obtained after ovarian hyperstimulation for in vitro fertilization (IVF) and gamete intrafallopian transfer (GIFT) were utilized to evaluate sperm/zona pellucida binding potential. Three groups of oocytes were evaluated: 1) uninseminated; 2) inseminated-unfertilized; and 3) fertilized-uncleaved. All oocytes had undergone germinal vesicle breakdown at the time of retrieval and were salt-stored (pH 7.2) for not more than 30 days. Sperm binding was recorded under hemizona assay (HZA) conditions using spermatozoa from eight fertile men (HZA control) and from 1) four teratozoospermic (HZA test) and 2) four normozoospermic (HZA test) infertile men. First, the mean numbers (+/- SD) of sperm tightly bound for fertile controls and teratospermic men to hemizonae from uninseminated oocytes were 69.7 +/- 16 and 14.5 +/- 7, respectively (P = 0.02). Likewise, hemizonae from uninseminated oocytes bound 102.0 +/- 19 and 114.0 +/- 28, respectively, for fertile controls and normospermic men (P = 0.5). Second, hemizonae obtained from inseminated-unfertilized IVF oocytes bound 44.2 +/- 12 and 19.7 +/- 6 for fertile controls and teratospermic men, respectively (P = 0.02). This category of oocytes bound 100.5 +/- 7 and 108.5 +/- 11 sperm, respectively, for fertile controls and normospermic semen (P = 0.3). Third, HZA results of fertilized but uncleaved oocytes showed a mean number of tightly bound sperm of 6.0 +/- 4 compared with 65.0 +/- 1 in control, uninseminated oocytes using fertile sperm. These results demonstrate that uninseminated and inseminated-unfertilized human oocytes, salt-stored under controlled pH conditions, give reliable information regarding sperm binding potential under HZA conditions.

Female↗
PubMed1994

Mechanism of calcium oscillations in fertilized rabbit eggs.

Changes in intracellular calcium concentrations ([Ca2+]i) occur at regular intervals following fertilization in eggs of all mammalian species studied to date. To investigate the mechanisms of their generation, rabbit eggs were injected with the fluorescent Ca2+ indicator fura-2 dextran. [Ca2+]i oscillations were associated with fertilization (n = 10) and inositol 1,4,5-trisphosphate (InsP3;IICR) appears to participate in their generation because injection of heparin (100 mg/ml in the pipette), a competitive InsP3 receptor antagonist, blocked or considerably delayed the fertilization [Ca2+]i rises in all eggs (8/8). Injection of guanosine 5'-0-(2-thiodiphosphate) (GDP beta[S]), a G-protein antagonist, which possibly reduced the production of InsP3, also resulted in inhibition of [Ca2+]i oscillations (n = 7). Ca2+ injection-induced Ca2+ release in fertilized eggs was observed by injection of CaCl2, which evoked intracellular Ca2+ release in all oscillating eggs (n = 14), but only in a few late fertilization stage nonoscillating eggs (7/19 eggs) and in none of the unfertilized eggs (n = 11). Injection of InsP3 (5 microM) between fertilization [Ca2+]i rises also elicited Ca2+ responses that were similar in peak [Ca2+]i to the fertilization [Ca2+]i rises (n = 5). In unfertilized eggs, injection of guanosine 5'-0-(3-thiotriphosphate) (GTP[S]; 5-20 mM), a stimulator of G-proteins, induced [Ca2+]i oscillations. CaCl2 injections, delivered between GTP[S]-induced [Ca2+]i rises, resulted in increased Ca2+ responses in 5/7 eggs. The results of this study indicate that IICR participates in the generation of fertilization-associated [Ca2+]i rises and that Ca2+ injection-induced Ca2+ release appears to be stimulated by a product of the phosphoinositide pathway. Furthermore, the time to reach threshold levels of InsP3 may dictate the periodicity of fertilization [Ca2+]i rises in rabbit eggs.

Animals↗
PubMed1999

Low fertility in aging roosters is related to a high plasma concentration of insulin and low testicular contents of ACTH and lactate.

Fertility in roosters peaks between 30 and 40 weeks of age and declines rapidly from about 50 weeks of age. Low-fertility, aging roosters have a higher density of elongated spermatids attached to Sertoli cells than do high-fertility roosters, but display normal spermatogenesis and ejaculated spermatozoa. Plasma levels of insulin and lactate and testicular contents of ACTH and lactate were compared in Cornish roosters aged 27 weeks (early state of sexual maturity), 37 weeks (high fertility), 67 weeks (reduced fertility), and 72 weeks (low fertility). Insulin may act as an endocrine regulator of Sertoli cell function, and ACTH as an autocrine regulator of Leydig cells for androgen production and as a paracrine regulator of Sertoli cells by amplifying FSH response. Lactate is the primary energy substrate of spermatocytes and spermatids in the adluminal compartment. Roosters aged 67 and 72 weeks had higher (P < 0.05) plasma insulin levels but lower (P < 0.05) testicular lactate content than roosters aged 27 and 37 weeks. The lower lactate content in testes of low-fertility roosters may reflect an increased consumption of lactate due to the higher density of elongated spermatids. Furthermore, the content of testicular ACTH was lower in low-fertility roosters than in 27-week-old roosters. These results suggest that ACTH may be involved indirectly in the mechanism responsible for the high density of spermatids in the tubuli and the lower spermatozoa concentration in the ejaculate of low-fertility roosters, as was reported in previous studies, since this hormone may serve as a paracrine regulator of Sertoli cell function.

Adrenocorticotropic Hormone↗
PubMed2002

Fertility assessment of hydatid cyst by proton MR spectroscopy.

BACKGROUND: Hydatid cysts, the larvae of the parasite Echinococcus granulosus, may lodge in any organ of intermediate hosts, namely, man and sheep. Complete cyst removal is the treatment of choice; however, spillage of fertile cysts during surgery leads to disease recurrence that may be prevented by preoperative detection of the fertility status of the cyst. With this perspective, ex vivo proton (1H) MR spectroscopy of hydatid fluid of human and sheep origin was performed to differentiate fertile from sterile cysts on the basis of their metabolite pattern. PATIENTS AND MATERIALS: Cysts of sheep and human origin were used as source of hydatid fluid. A fraction of this fluid was tested for cyst fertility and the rest was used for ex vivo1H spectroscopy. Histopathology of the cyst wall was done as a gold standard for this study. RESULTS: Of 10 sheep samples, 7 were fertile and 3 were sterile, while among 6 human samples, 5 were fertile and 1 was sterile. Spectroscopic and histopathological results corroborated each other. The fluid from microbiologically proven fertile cysts contained malate and fumarate along with other resonances and the histopathology of the fertile cyst wall demonstrated germinal lining and protoscoleces. CONCLUSIONS: The ex vivo spectroscopic differentiation of fertile and sterile cysts may be a stepping-stone for their in vivo separation in future and thus help in framing strategies for percutaneous/surgical management.

Animals↗
PubMed1988

Hyaluronidase removal of the cumulus oophorus increases in vitro fertilization.

The effect of hyaluronidase removal of the cumulus oophorus on the in vitro fertilization rate of oocytes obtained from patients with poor oocyte fertilizability has been evaluated. Eighty-eight oocytes were obtained from 13 patients undergoing in vitro fertilization and embryo transfer (IVF-ET) for indications of male-factor, immunological, and idiopathic infertility. In addition, patients in whom fertilization did not occur on previous IVF cycles were evaluated in the study. The oocytes of each individual patient were randomly assigned into a treatment (removal of the cumulus; N = 40 oocytes) or nontreatment group (control; N = 48 oocytes). Hyaluronidase was used to remove the cumulus immediately following oocyte retrieval, and insemination was performed 6-8 hr later. The overall oocyte fertilization rate (both treated and untreated) was 42%. The treatment group demonstrated a higher rate of fertilization compared to the nontreatment group (55% vs 31%; P less than 0.05). Examination of various patient groups revealed a statistically significant difference in fertilization rates between the treated and the untreated oocytes only in the "no previous fertilization" group (60% vs 28%; P less than 0.05). A higher rate of fertilization of the treated oocytes was also seen in the immunologic infertility group, however, statistical significance was not achieved (50% vs 25%; P = 0.07). Only one clinical pregnancy was achieved in this group of 13 patients. We conclude that in this group of patients, removal of the cumulus prior to insemination may, in some cases, increase the fertilization potential of the oocyte.

Female↗
PubMed1976

Population dose from natural radionuclides in phosphate fertilizers.

The natural radionuclide content of mineral phosphate fertilizers has been determined gammaspectrometrically. The investigations comprised ca. 70% of the mineral phosphate fertilizers authorized and used in the Federal Republic of Germany (FRG). At maximum, we found specific activities of 62 nCi Unat/kg, 23 nCi 226Ra/kg, 1.6 nCi Thnat/kg and 262 nCi 40K/kg. The mean values, weighted by the percentual agricultural consumption of the main phosphate fertilizer groups in 1973/74 and related to the phosphate content, amounted to 58, 40, 2, and 584 nCi/kg P2O5 for Unat, 226Ra, Thnat, and 40K respectively. This resulted in an annual distribution due to phosphate fertilizing of about 3.9 muCi Unat, 2.7 muCi 226Ra, 0.1 muCi Thnat, and 39.9 muCi 40K per ha of arable or pasture land in 1973/74 on the average. From these values the air dose rates over agricultural areas have been estimated under extreme conservative assumptions resulting in an additional external exposure of members of the population of 0.02 mrd/a on the average and 0.4 mrd/a in the region of highest phosphate fertilizing intensity. If it is assumed that radium contained in phosphate fertilizers were completely accumulated in the soils during the last 80 years, this value would be raised to 0.3 mrd/a on the average. The occupational external radiation exposure due to natural radionuclides contained in phosphate fertilizers was estimated to be 0.1 mrd/a on the average and 2.3 mrd/a at maximum for persons working in agriculture. These estimates show that natural radionuclides in phosphate fertilizers contribute but very little to the mean terrestrial radiation exposure of the population which is 50 to 55 mrd/a in Germany. Only for the small group of persons working in fertilizer production plants or storehouses a significant increase of the external radiation exposure has to be expected which could reach a doubling of the mean natural exposure value.

Agriculture↗
PubMed1995

Second polar body extrusion is highly predictive for oocyte fertilization as soon as 3 hr after intracytoplasmic sperm injection (ICSI).

OBJECTIVE: Our objective was to evaluate the time course and the predictive value of the extrusion of the second polar body after intracytoplasmic injection (ICSI) related to the fertilization rate, embryo cleavage and quality. SETTING: The setting was the in vitro fertilization program of a university hospital. PATIENTS: Twenty-one patients were treated with intracytoplasmic single sperm injection either for fertilization failure in IVF, low fertilization in IVF (< 5%), or severe male factors. DESIGN: One hundred thirty-five of 205 metaphase 2 oocytes treated with intracytoplasmic single sperm injection were observed 1, 2, and 3 hr after the assisted fertilization procedure. Extrusion of the second polar body was recorded. For each of these oocytes, fertilization was noted 18 hr after ICSI and cleavage and embryo quality were assessed 24 hr later. The 70 remaining oocytes were used to assess a possible negative effect of repeated exposure to light microscopy. RESULTS: The extrusion of the second polar body 3 hr after injection was an observation with a sensitivity of 0.87, a specificity of 0.58, and a high positive predictive value (0.90) toward oocyte fertilization. Twenty-nine and four-tenths percent of the oocytes extruded a second polar body within the first hour, 56.6% within the first 2 hr, and 78.3% had a second polar body 3 hr after injection. This time course was related neither to the speed of embryo cleavage nor to the embryo quality. Fertilization, cleavage, and embryo quality were not affected by repeated observation as deduced from comparison with the control group and confirmed by a high pregnancy (62% per oocyte retrieval) and implantation rate (22% per replaced embryo). CONCLUSION: Oocytes can be checked, in all safety, 3 hr after a single sperm injection for the presence of a second polar to predict oocyte fertilization with a high certainty.

Chorionic Gonadotropin↗
PubMed1986

Failure of fertilization as a cause of preimplantation loss induced by methyl chloride in Fischer 344 rats.

Methyl chloride (MeCl) is a testicular and epididymal toxicant in the Fischer 344 rat that induces significant decreases in sperm quality in males and significant increases in preimplantation embryonic loss in females mated to exposed males. This study examined the possibility that these losses are due to failure of fertilization and not to preimplantation embryonic death. Groups of males either were exposed to 1000 or 3000 ppm MeCl 6 hr/day for 5 days or received a single ip injection of 0.2 mg/kg triethylenemelamine (TEM) on Day 5 and were bred to two females weekly for up to 8 weeks. Females were killed 12 hr postmating; embryos and ova were isolated and scored as fertilized or unfertilized. Nearly 90% (602/683) of the normal ova recovered from females bred to control males were fertilized, and fertilization rates in the 1000-ppm MeCl and TEM groups were not significantly depressed from that level. The percentage of fertilized ova in the 3000-ppm MeCl group was significantly decreased, ranging from 3 to 72% over the 8 weeks. The frequency of unfertilized ova in this group always equaled or exceeded the frequency of preimplantation loss recorded in an earlier dominant lethal assay. In contrast, only a fraction of the preimplantation losses caused by the genotoxicant TEM could be accounted for by failure of fertilization. After culture of fertilized ova for 24 hr, only the TEM group exhibited a significant decrease in the number of fertilized ova which cleaved (85 vs 96% in the control). We conclude that the preimplantation loss caused by MeCl exposure is due to failure of fertilization and not to a genotoxic effect of MeCl. The methods used here permit a more accurate assessment of the reproductive toxicity of a chemical by discriminating between its cytotoxic and genotoxic effects.

Animals↗