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PubMed1993

Abnormal sperm-mucus penetration test predicts low in vitro fertilization ability of apparently normal semen.

OBJECTIVE: To investigate whether Kremer's sperm-mucus penetration test may predict sperm fertilizing ability in IVF. DESIGN: Kremer's test was prospectively performed on semen samples used for 66 consecutive IVF trials and compared with the fertilization rates and fertilization failure rates observed. RESULTS: Fertilization rates were significantly reduced in cases of abnormal Kremer's test (42% versus 51%; n = 745 oocytes with a statistically insignificant increase in fertilization failure rates (21% versus 10%; n = 66 trials). For abnormal semen, fertilization rates (39% versus 39%; n = 208 oocytes) and fertilization failure rates (20% versus 28%; n = 17 trials) were similar regardless of Kremer's test result. For normal semen, an abnormal Kremer's test implied a significant decrease in fertilization rates (44% versus 54%; n = 537 oocytes) with a statistically insignificant increase in fertilization failure rates (21% versus 6%; n = 49 trials). CONCLUSIONS: Abnormal Kremer's test results identify patients with a decreased in vitro fertilizing ability despite apparently normal semen samples and a group with very low fertilizing failure risk in case of normal semen samples and normal Kremer's test. Kremer's test does not add any predictive value to sperm analysis in the case of abnormal semen samples. These observations point out the importance of the male factor in fertilization failure even in the case of normal semen analysis.

Cervix Mucus↗
PubMed1987

Reversible inhibition of rabbit sperm-fertilizing ability by cholesterol sulfate.

Experiments were carried out to examine the influences of lipid treatments on the fertilizing ability of rabbit spermatozoa. In vitro insemination of tubal oocytes with in vivo-capacitated sperm resulted in fertilization (IVF) of 81% of the oocytes (38/47) and in vitro development to the morula or blastocyst stage of 92% (35/38) of the embryos within 72 to 96 h. Treatment of capacitated sperm with cholesterol (Ch, up to 100 micrograms/ml) did not reduce the proportion of oocytes fertilized (fertilization rate, 100%, 8/8). Cholesterol-3-sulfate (Chs) at concentrations of 100 and 1,000 micrograms/ml significantly (p less than 0.001) decreased fertilization rates to 13.6% (8/59), and 3.5% (1/29), respectively. Hypercholesterolemic serum (HChS, 1295 mg cholesterol/dl vs. 45 +/- 18 mg/dl in normal serum), incubated for 2 h with in vivo-capacitated sperm, did not inhibit fertilization. However, a decreasing trend in fertilization was associated with increasing levels of HChS cholesterol. ChS effectively inhibited the fertilizing ability of capacitated sperm (p less than 0.05) compared to control, Ch, and HChS. In another experiment the use of ChS at 100 micrograms/ml significantly (p less than 0.05) reduced the fertilization rate from 56.6% (30/53) to 14.3% (7/49). When a phospholipid-enriched serum medium was added to sperm treated with 100 micrograms ChS/ml, the fertilization rate was 57.7% (23/40), which was not significantly (p less than 0.05) different from the fertilization rate of sperm not treated with ChS (56.6%, 30/53). These data suggest that rabbit sperm fertilizing ability can be reversibly inhibited by cholesterol sulfate.

Animals↗
PubMed1990

Effects of gonadotropins and granulosa cell secretions on the maturation and fertilization of rat oocytes in vitro.

Fully grown germinal vesicle-stage oocytes are induced to resume meiosis and acquire the capacity to undergo fertilization in response to a surge of gonadotropins. The present study examined possible direct and indirect roles of gonadotropins in the maturation and fertilization of rat oocytes by determining 1) the effect of exogenous administration of gonadotropins (priming) to immature rats prior to oocyte collection on the capacity of oocytes to undergo maturation and fertilization in vitro, 2) the effect of follicle-stimulating hormone (FSH) in the maturation media on the resumption of meiosis and subsequent capacity of oocytes to undergo fertilization, and 3) the capacity of oocytes to undergo maturation and fertilization following culture in preovulatory follicular fluid or in conditioned media obtained from gonadotropin-stimulated granulosa cell (GC) cultures. In the first experiment, oocytes from unprimed rats underwent spontaneous meiotic maturation in vitro and 17% underwent subsequent fertilization. Priming increased the proportion of oocytes undergoing fertilization. Maturation of oocytes in media supplemented with various concentrations of FSH or for various lengths of time (6-16 h) in medium with 500 ng FSH/ml indicated that FSH slowed the rate of meiotic maturation, but had no effect on the capacity of the oocytes to be fertilized. Oocytes obtained from primed animals and cultured in the presence of preovulatory follicular fluid were fertilized in proportions similar to those cultured in serum-containing medium. In the third experiment, medium conditioned by FSH-stimulated GC for 40 h slowed the rate of meiotic maturation; the addition of luteinizing hormone (LH) to the FSH-stimulated cells produced a medium in which the rate of oocyte maturation was not different from that of control oocytes (in medium from unstimulated cells). Medium conditioned by FSH- or LH-stimulated GC, but not fibroblasts, increased the proportions of oocytes undergoing fertilization following maturation in those media. FSH + LH stimulation of GC increased the fertilization of oocytes to proportions significantly higher than with either gonadotropin alone. These data suggest that GC respond to gonadotropin stimulation by providing a factor(s) that regulates the rate of oocyte maturation and promotes the capacity of oocytes to undergo fertilization.

Animals↗
PubMed1989

Evidence that the voltage-dependent component in the fertilization process is contributed by the sperm.

To investigate the mechanisms that account for the voltage dependence of fertilization and provide an electrical block to polyspermy, we studied cross-fertilizations between three species of amphibians having different degrees of voltage dependence. Anurans, such as the toad Bufo japonicus, as well as the primitive urodele Hynobius nebulosus, have voltage-dependent fertilization; other urodeles, such as Cynops pyrrhogaster, have voltage-independent fertilization (Y. Iwao, 1989, Dev. Biol. 134, 438-445). Entry of Hynobius sperm into Cynops eggs was blocked by clamping the egg's membrane potential at +40 mV, as is the case for fertilization of Hynobius eggs with Hynobius sperm, but not for fertilization of Cynops eggs with Cynops sperm. Therefore, fertilization was voltage dependent in an experimental condition where only the sperm could be contributing this characteristic. The voltage-dependent properties of fertilization between Bufo eggs and Hynobius sperm were also characteristic of the sperm species; fertilization was blocked at +50 mV as in Hynobius fertilization, but not at +20 mV as in Bufo fertilization. These results support the conclusion that the voltage dependence of fertilization results from a component contributed by the sperm.

Amphibians↗
PubMed2026

In vitro fertilization-conceived offspring exhibit altered Long Interspersed Nuclear Elements-1 retrotransposition dynamics associated with long-term disease risks.

BACKGROUND: In vitro fertilization has transformed reproductive medicine, yet offspring conceived through in vitro fertilization display elevated risks for diverse long-term health conditions, with underlying mechanisms unclear. Long Interspersed Nuclear Elements-1, a mobile genetic element responsive to environmental stress, represents a potential mediator. OBJECTIVE: This study aimed to test the hypothesis that in vitro fertilization procedures may act as an embryonic stressor that alters Long Interspersed Nuclear Elements-1 dynamics, potentially contributing to genomic instability associated with long-term disease susceptibility. STUDY DESIGN: Umbilical cord blood or peripheral blood from 33 in vitro fertilization and 42 naturally conceived neonates were collected for whole-genome sequencing. Total Long Interspersed Nuclear Elements-1 proportion in individual genome was counted with Bowtie2 software. De novo Long Interspersed Nuclear Elements-1 insertion and Long Interspersed Nuclear Elements-1 deletion were detected with Mobile Element Locator Tool. Three parent-matched in vitro fertilization-naturally conceived sibling pairs were included to control for genetic background. Disease association analysis was performed for genes within 500 kb of differential Long Interspersed Nuclear Elements-1 sites in The Database for Annotation, Visualization and Integrated Discovery (DAVID). Statistical analysis was performed using the R language. RESULTS: In vitro fertilization offspring demonstrate elevated global Long Interspersed Nuclear Elements-1 content compared to naturally conceived controls (P=.04). This finding was corroborated in 3 sibling pairs from identical genetic backgrounds, where in vitro fertilization-conceived children consistently exhibited higher Long Interspersed Nuclear Elements-1 levels than their naturally conceived siblings. Eleven genomic loci with differential Long Interspersed Nuclear Elements-1 insertion frequencies and 14 loci with differential Long Interspersed Nuclear Elements-1 deletion frequencies between in vitro fertilization offspring and naturally conceived controls were identified. Notably, these differential Long Interspersed Nuclear Elements-1 sites demonstrated significant enrichment near genes implicated in metabolic, cardiovascular, neuropsychiatric, and neoplastic diseases, conditions associated with in vitro fertilization conception. CONCLUSION: These findings provide preliminary evidence that in vitro fertilization conception is associated with increased Long Interspersed Nuclear Elements-1 content and altered genomic distribution of Long Interspersed Nuclear Elements-1 elements. The proximity of these differential Long Interspersed Nuclear Elements-1 sites to disease-associated genes suggests a plausible genomic mechanism linking in vitro fertilization-associated embryonic stress to elevated disease risk. This work provides valuable molecular insights that may inform the ongoing discussion about assisted reproductive technology safety and suggests that continued attention to genomic integrity in in vitro fertilization-conceived individuals would be beneficial.

Humans↗
PubMed2006

Fertility-associated proteins in Nelore bull sperm membranes.

The present study was undertaken to evaluate the protein composition of the sperm membranes (SM) of Nelore bulls, assessing protein markers associated with bull fertility, and whether these markers can be used for predicting bull fertility. Samples were obtained of 20 Nelore bulls, with fertility ranked and divided into three groups (greater, normal and least). To rank the bull's fertility weighted classification was used (according to the number of pregnant cows, number of AI cows and number of herds, considering three different breeding seasons), using the PROC GENMOD as a statistical model, with 99% significance. A total of 7897 Nelore cows, randomly distributed among 28 different farms, were considered in the statistical analyses. The bulls were divided into three fertility groups (pregnancy rates): greater (%F > 80), normal (79 < %F > 71) and least (< 68%F) with 3, 13 and 4 bulls, respectively. Two-dimensional gel electrophoresis (2DE) of sperm membranes indicated in 27 spots (SM40, SM53, SM69, SM93, SM102, SM111, SM137, SM138, SM189, SM196, SM201, SM202, SM204, SM225, SM236, SM237, SM239, SM241, SM246, SM247, SM275, SM283, SM342, SM346, SM355, SM372, SM391) was prevalent in the higher fertility group, and just one spot (SM244) was prevalent in the lower fertility group. Spots SM244 and SM239 had their identification defined by PMF/MALDI-MS, as BSP-A3 and aSFP, respectively. Both these proteins showed a great potential for predicting bull's fertility. The amount of aSFP was 8.5 times greater in the sperm membrane protein profile of the higher fertility groups of Nelore bulls. Besides that, the BSP-A3 was 2.5 times greater in the lower fertility group. For the other spots potentially associated with fertility not yet identified, additional tests will be necessary, but it is clear that the 2D electrophoresis of the sperm membrane can be used for a new approach to predict Nelore bull fertility.

Animals↗
PubMed2006

Phosphorus availability to rice (Oriza sativa L.)-wheat (Triticum estivum L.) in a Vertisol after eight years of inorganic and organic fertilizer additions.

Integrated use of inorganic fertilizer N and well decomposed cattle manure (CM) or 30-35 days old Parthenium (Parthenium hysterophorus L.), a weed grown off site as green manure (GM) under repeated applications of fertilizer P and urea N for eight years in a rice (Oriza sativa L.)-wheat (Triticum estivum L.) sequence was studied on transformation of fertilizer P applied to soil at the National Research Center for Weed Science, Jabalpur, India. Based on the results, it appeared that, repeated applications of 52 kg super-phosphate P resulted in a marked increase in Olsen P linearly with time. Conjunctive use of urea fertilizer N with organic manure resulted in a larger increase in Olsen P in the Vertisol. Studies further revealed that the greater accumulation of fertilizer P applied in excess to crop removal occurred in inorganic P in the plots receiving only fertilizer N. However, plots receiving fertilizer N along with organic manures led to P accumulation predominantly in organic forms. The study suggests that these two pools of P acted as a sink when fertilizer P was applied in excess to crop removal and are bio-chemically active. The Olsen P status after 8 cycles of rice-wheat crops revealed that the average amount of fertilizer P required after adjusting for crop uptake to increase Olsen P by 1 mg kg(-1) soil was 7.2 kg Pha(-1) in the plots receiving only fertilizer N. Whereas, application of 5t FYM or 6t GM reduced it to 4.6 kg Pha(-1). The plots receiving manure always maintained a greater concentration of Olsen P. The application of CM or GM with fertilizer N enriched short-term inorganic P as well as long-term organic P fertility. After eight years, larger concentrations of organic P in the subsurface layer (16-30 cm), compared to initial values, indicates downward movement of P in organic forms.

Agriculture↗
PubMed1983

Association of birth outcome with subsequent fertility.

The association between birth outcome and subsequent fertility was analyzed by using linked Norwegian birth certificates. All births of order 1, 2, and 3 which occurred during 1967 through 1974 were considered index births; there were approximately 207,000 index births of order 1, 165,000 of order 2, and 87,000 of order 3. The mothers' fertility after these index births was summarized with a life-table technique. Fertility was most pronounced if there were no survivors of an index birth, intermediate if there was one survivor, and lowest if both members of a set of twins survived. Advanced maternal age was associated with markedly reduced fertility. The sex of a surviving singleton had little effect on a mother's subsequent fertility. However, there was a sex-related difference if index twins survived; fertility was lower after the birth of unlike-sex twins and higher after the birth of like-sex twins. This probably reflects reproductive limitation rather than a differential fecundity for mothers of dizygotic and monozygotic twins. A comparison of fertility after births of like-sex and unlike-sex twins with one survivor may indicate that mothers of dizygotic twins were more fertile, but the number available for study was small. Reproduction among women who had two index births during 1967 through 1974 was examined separately. Fertility was most marked if neither of the first two infants survived and lowest where three survived (i.e., where one of the index births involved twins). If there were two survivors, the sex composition of the pair influenced fertility; fertility was greater if the two survivors were of the same sex and lower if they were of unlike sex. Since a woman who has an unfavorable outcome in one pregnancy will be at a higher risk of having an unfavorable outcome in a subsequent pregnancy, the higher fertility of such women will, to some degree, inflate the frequency of unfavorable outcomes in a population of births.

Adolescent↗
PubMed2001

Male partner screening before in vitro fertilization: preselecting patients who require intracytoplasmic sperm injection with the sperm penetration assay.

OBJECTIVES: To determine the diagnostic accuracy of the sperm penetration assay (SPA) and standard semen parameters for subsequent fertilization in in vitro fertilization-embryo transfer (IVF-ET). DESIGN: Prospective study. SETTING: Andrology Laboratory, and university research laboratory. PATIENTS: Two hundred sixteen couples undergoing male-partner screening before IVF-ET (265 cycles). INTERVENTION(S): Male-partner screening (semen analyses [SA] and SPA), standard IVF-ET procedures, follow-up of fertilization in IVF-ET. MAIN OUTCOME MEASURE(S): Diagnostic accuracy of SA and SPA for prediction of fertilization in IVF-ET. RESULT(S): The SPA predicted IVF fertilization with high negative (84%) and positive (98%) predictive rates, and correct prediction in 88% of cycles. In contrast, sperm concentration, motility, morphology, and complete SA showed poor diagnostic accuracy, with correct prediction of IVF fertilization in 64%, 65%, 45%, and 68% of cycles, respectively. CONCLUSION(S): Very low sperm concentration and/or motility were good predictors of poor IVF fertilization, however, low to normal semen parameters were not predictive of successful IVF fertilization. The SPA is a useful screening tool that predicts IVF fertilization with high diagnostic accuracy. The SPA may be useful to discriminate between those couples with a high probability of normal fertilization in IVF and those with a low probability of normal fertilization that may benefit from assisted fertilization by intracytoplasmic sperm injection (ICSI).

Animals↗
PubMed2002

Follicular development and steroid concentrations in cows with different levels of fertility raised under nutritional stress.

The aim of the present study was to characterize ovarian follicular development and steroid concentrations during postpartum and the estrous cycle of Brangus Ibagé cows (3/8 Nelore + 5/8 Aberdeen Angus) with different levels of fertility. Cows were classified as having high or low fertility according to the calving interval (CI). The average CI of the herd from which cows used in this study were selected was 404.6+/-5.44 and 711.2+/-20.89 days for the high and low fertility groups, respectively. Four cows of high fertility and five cows of low fertility had calves removed between 70 and 100 days after parturition. Ovarian activity was monitored daily by ultrasound for 16 days after calf removal. Days to emergency of the first follicular wave after calf removal, number of follicles with diameter >9 mm, growth rate of largest follicle, maximum diameter of largest follicle, length (days) and number of follicular waves were recorded. During this period, blood was collected daily for measurements of serum progesterone (P(4)) and estradiol (E(2)) concentrations. In another experiment, ovarian activity and P(4) and E(2) concentrations were examined during estrous cycle in five cows of high fertility and four cows of low fertility. Ovarian activity and steroid concentrations were assessed from the day prior to estrus to the 15th day of the estrous cycle (estrus = day 0). In postpartum cows of high fertility, the total number of follicles >5mm and the maximum diameter of the largest follicle were higher than in cows of low fertility (P < 0.05). Concentrations of P(4) and E(2) did not differ between groups in the postpartum cows. However, E(2) increased 5 days after calf removal (around 90 days of postpartum) in the high fertility group, followed by an increase in P(4) with average values indicating ovulation around 100 days postpartum. In cycling cows, the profile of follicular development was similar between cows of high and low fertility. There was no difference between groups for number of follicles >5mm, but the day effect was significant (P < 0.01). Plasma concentrations of P(4) and E(2) were similar in both groups. These data suggest that cows, from a population raised in the same environment have different fertility as a consequence of individual physiological characteristics.

Animal Nutritional Physiological Phenomena↗
PubMed2006

Period and cohort dynamics in fertility norms at the onset of the demographic transition in Kenya 1978-1998.

A characteristic of African pre-transitional fertility regimes is large ideal family size. This has been used to support claims of cultural entrenchment of high fertility. Yet in Kenya fertility rates have fallen. In this paper this fall is explored in relation to trends in fertility norms and attitudes using four sequential cross-sectional surveys spanning the fertility transition in Kenya (1978, 1984, 1989 and 1998). The most rapid fall in the reported ideal family size occurred between 1984 and 1989, whilst the most rapid fall in the total fertility rate occurred 5 to 10 years later, between 1989 and 1998. Thus these data, spanning the fertility transition in Kenya, support the traditional demographic model that demand for fertility limitation drives fertility decline. These data also suggest that the decline in fertility norms over time was partly a period effect, as the reported ideal family size was seen to fall simultaneously in all age cohorts, and partly a cohort effect, as older age cohorts reporting higher ideal family sizes were replaced by younger cohorts reporting lower ideal family sizes. These data also suggest that a new fertility norm of four children may have developed by 1989 and continued until 1998. This is consistent with, and perhaps could have been used to predict, the stall in the Kenyan fertility decline after 1998.

Adolescent↗
PubMed1998

Treatment policy after poor fertilization in the first IVF cycle.

PURPOSE: The chance of recurrence of poor fertilization in a second in vitro fertilization (IVF) cycle was assessed. METHODS: Total fertilization failure was defined, and the relationship between the fertilization rate and the number of motile sperm cells per milliliter of semen was assessed. Patients with a total fertilization failure or poor fertilization (20% or less of the oocytes fertilized) were divided into three subgroups with different chances of fertilization and were followed in a subsequent IVF cycle. RESULTS: The recurrence rate of total fertilization failure was high in all three groups (45-70%), and poor fertilization frequently occurred in the second cycle (50-75%). CONCLUSIONS: Poor fertilization frequently recurs in the second IVF cycle. The use of intracytoplasmic sperm injection could be considered after fertilization of 20% or less of oocytes in the first cycle, irrespective of the number of motile sperm cells per milliliter of semen.

Female↗
PubMed1994

Importance of bicarbonate/CO2 for fertilization of pig oocytes in vitro, and synergism with caffeine.

Fertilization of pig oocytes was performed in vitro in modified Tyrode's media in which either HEPES or bicarbonate/CO2, or both, were included as buffer systems; caffeine (2 mM) was also included in some of the media because it is a reported stimulant of fertilization. The composition of the bicarbonate-containing media was designed so as to maintain the same pH and osmolality as bicarbonate-free media. The inclusion of bicarbonate during gamete co-incubation in caffeine-containing medium led to high levels of fertilization (66% of 238 mature oocytes were fertilized). However, essentially no fertilization occurred if bicarbonate was replaced with HEPES (0.7% of 146 oocytes were fertilized; significantly different, P < 0.001). Inclusion of HEPES in bicarbonate-containing medium during gamete co-incubation did not affect fertilization, showing that HEPES did not exert an inhibitory effect. Omission of bicarbonate during sperm preincubation also did not affect fertilization. If caffeine was included in bicarbonate-containing medium, 73% of 311 oocytes were fertilized whereas if caffeine was omitted only 14% of 326 oocytes were fertilized (significantly different, P < 0.001). In the absence of bicarbonate, when fertilization was very low, caffeine had no stimulatory effect. The results indicate that bicarbonate is essential for pig fertilization in vitro, but that caffeine exerts a synergistic stimulatory effect.

Animals↗
PubMed1997

The Chlamydomonas mating type plus fertilization tubule, a prototypic cell fusion organelle: isolation, characterization, and in vitro adhesion to mating type minus gametes.

In the biflagellated alga Chlamydomonas, adhesion and fusion of the plasma membranes of gametes during fertilization occurs via an actin-filled, microvillus-like cell protrusion. Formation of this approximately 3-microm-long fusion organelle, the Chlamydomonas fertilization tubule, is induced in mating type plus (mt+) gametes during flagellar adhesion with mating type minus (mt-) gametes. Subsequent adhesion between the tip of the mt+ fertilization tubule and the apex of a mating structure on mt- gametes is followed rapidly by fusion of the plasma membranes and zygote formation. In this report, we describe the isolation and characterization of fertilization tubules from mt+ gametes activated for cell fusion. Fertilization tubules were detached by homogenization of activated mt+ gametes in an EGTA-containing buffer and purified by differential centrifugation followed by fractionation on sucrose and Percoll gradients. As determined by fluorescence microscopy of samples stained with a fluorescent probe for filamentous actin, the method yielded 2-3 x 10(6) fertilization tubules/microg protein, representing up to a 360-fold enrichment of these organelles. Examination by negative stain electron microscopy demonstrated that the purified fertilization tubules were morphologically indistinguishable from fertilization tubules on intact, activated mt+ gametes, retaining both the extracellular fringe and the internal array of actin filaments. Several proteins, including actin as well as two surface proteins identified by biotinylation studies, copurified with the fertilization tubules. Most importantly, the isolated mt+ fertilization tubules bound to the apical ends of activated mt- gametes between the two flagella, the site of the mt- mating structure; a single fertilization tubule bound per cell, binding was specific for gametes, and fertilization tubules isolated from trypsin-treated, activated mt+ gametes did not bind to activated mt- gametes.

Animals↗
PubMed2000

Is the mouse a clinically relevant model for human fertilization failures?

This study compares failed fertilization oocytes from patients participating in an in-vitro fertilization (IVF) programme with failed fertilization oocytes from B6SJLF(1)/J mice, in order to characterize and describe the distribution of DNA in oocytes that do not undergo normal fertilization. Our goal is to evaluate the mouse IVF system as a model to gain insight into reasons for human fertilization failures. All oocytes were stained with the vital fluorescent dye, Hoechst 33342, which rapidly stains double-stranded DNA. Of the 237 human oocytes that had been scored as failed fertilization by brightfield microscopy, 61 (25.7%) showed the presence of at least one spermatozoon within the oocyte cytoplasm. In contrast, out of 69 failed fertilization mouse oocytes, only one oocyte showed the presence of a spermatozoon within its cytoplasm. Mouse failed fertilization oocytes exhibited a significantly lower internal sperm rate (P < 0.0001) than human failed fertilization oocytes. Human failed fertilization oocytes show a higher incidence of sperm penetration, but the cytoplasm fails to support pronuclear development, whereas, at least in this strain, mouse failed fertilization oocytes arise from an inability of the spermatozoa to penetrate the oocyte. This study suggests that the mouse is not a clinically relevant model for human fertilization failures.

Animals↗
PubMed1989

Fertilization of human oocytes in capillary tubes with very small numbers of spermatozoa.

Human oocytes can be fertilized with high rates of success under in-vitro conditions even if only low numbers of spermatozoa are used. A culture system has been developed in which fertilization is performed in haematocrit capillary tubes (length 75 mm; i.d. 0.8-0.9 mm). Oocytes were fertilized in 5-10 microliters of different sperm suspensions containing a total of 500, 1000, 2000 and 4000 spermatozoa per oocyte (0.1-0.4 x 10(6) spermatozoa/ml). Oocytes were obtained from 10 patients participating in an in-vitro fertilization programme; of these, 32 oocytes were fertilized in capillary tubes and 32 oocytes were cultured using standard methods (1 ml culture medium in tissue culture tubes; 0.1-0.2 x 10(6) spermatozoa/ml). The overall fertilization rate of oocytes cultured in tissue culture tubes was 78% (25/32) and the fertilization rates in capillary tubes using 4000, 2000, 1000 or 500 spermatozoa per oocyte were 71% (5/7), 86% (6/7), 60% (6/10) and 50% (4/8), respectively. The fertilization rate of mature oocytes was higher compared with immature oocytes when fertilization was performed in culture tubes (83 and 63%) or in capillary tubes (74 and 44%). Fertilization in capillary tubes using a 10 microliter of oocyte and spermatozoa suspension compared to 5 microliters seemed to provide better culture conditions, resulting in higher fertilization and cleavage rates. These preliminary results indicate that fertilization of human oocytes under in-vitro conditions can be achieved even with very low numbers of spermatozoa.

Female↗
PubMed1983

Factors affecting successful in vitro fertilization of bovine follicular oocytes.

These experiments were designed to define and optimize the efficiency of a system whereby bovine oocytes could be fertilized in vitro. The frequency of ova penetrated and the stage of fertilization were the end points examined. All experiments utilized cumulus-oocyte complexes from 1- to 5-mm follicles which were matured in vitro prior to fertilization. The experiments were designed to examine the effects of the following factors on fertilization: 1) pretreatment of sperm with ionomycin (a Ca++ ionophore), 2) preincubation of sperm at a high concentration and the presence of hypotaurine and epinephrine during fertilization, 3) the use of either follicle-stimulating hormone (FSH) or cAMP for the induction of cumulus expansion prior to fertilization, and 4) the need for the presence of cumulus cells during fertilization. Sperm exposure to ionomycin or preincubation at high sperm concentrations was not necessary for fertilization. The presence of hypotaurine and epinephrine during fertilization improved (P less than 0.05) the quality of fertilization (i.e., higher frequencies of oocytes with both female and male pronuclei were observed). However, they did not increase the percentage of ova penetrated (P greater than 0.05). Fertilization frequencies were not different (P greater than 0.05) between oocytes with cumulus expansion induced by FSH or cAMP. However, the use of either treatment resulted in higher fertilization rates when compared to untreated controls (P less than 0.05). Finally, while the presence of cumulus cells was not necessary for penetration of ova, increased frequencies of ova with both male and female pronuclei were found when cumuli were present (P less than 0.05).

Animals↗
PubMed2004

The population impact of HIV on fertility in sub-Saharan Africa.

OBJECTIVES: To examine new evidence from studies on the estimates of the fertility rate ratio comparing HIV-infected and uninfected women, of the population change in total fertility attributable to HIV, and to review the evidence of changes in fertility in HIV-uninfected women. DESIGN: A review and analysis of data from the many individual studies that have examined the associations between HIV/AIDS and fertility. METHODS: Data from sub-Saharan Africa were collected from published studies, personal communications and the Demographic and Health Surveys. A mathematical model was used to demonstrate the impact of the HIV/AIDS epidemic on the number of births in Uganda. RESULTS: Fertility was lower among HIV-infected women than HIV-uninfected women, with the exception of those aged 15-19 years, in whom the selective pressure of sexual debut on pregnancy and HIV infection led to higher fertility rates among the HIV infected. This fertility differential resulted in a population-attributable decline in total fertility of 0.37% (95% confidence interval 0.30%, 0.44%) for each percentage point of HIV prevalence. The evidence for fertility changes in HIV-uninfected women was ambiguous. An estimated reduction of 700 000 births occurred in Uganda, as a result of the reduced fertility in HIV-infected women and premature mortality among reproductive age women. CONCLUSION: Large fertility differentials existed between HIV-infected and uninfected women, with substantial variation by age. The extent to which these could be attributed to the direct impact of the epidemic on both infected and uninfected women, as opposed to pre-existing differences in their fertility, merits further study.

Adolescent↗