[Autonomic innervation and male fertility: an underdeveloped area of fertility studies. I].
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Autonomic Nervous System↗
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Eight generations of selection for duration of fertility of frozen-thawed semen in the chicken.
The response to eight generations of selection for duration of fertility of frozen-thawed chicken semen, the correlated responses of other fertility parameters of frozen-thawed semen and the fertility of fresh semen, and the heritabilities of frozen-thawed and fresh semen were studied. The selected and control lines were derived from a base meat-type control male population developed at Peel's Poultry Farm Ltd., Port Perry, Ontario. Selection has improved duration of fertility of frozen-thawed semen significantly (P less than .01) with the mean increasing from 1 day in Generation 1 to 5 days in Generation 8 and an average improvement per generation of .29 day since Generation 3. There were significant (P less than .01) correlated increases in percent fertility for 2 to 8 days postinsemination and percent fertility for the duration of fertility of frozen-thawed semen as well as the fertility of fresh semen. Percent hatchability of fertile eggs of frozen-thawed semen did not change. In Generation 8, means and standard errors of fertility parameters of frozen-thawed semen in the selected and control lines, respectively, were: 38.54 +/- 1.39 and 25.58 +/- 1.77 for percent fertility for 2 to 8 days postinsemination, 47.73 +/- 3.54 and 32.02 +/- 2.17 for percent fertility for the duration of fertility, and 78.21 +/- 1.56 and 79.27 +/- 2.53 for percent hatchability of fertile eggs. For fertility of fresh semen, means and standard errors were: 12.69 +/- .20 and 11.54 +/- .42 for duration of fertility, 82.91 +/- 1.45 and 75.71 +/- 2.83 for percent fertility for 2 to 8 days postinsemination, and 71.89 +/- 1.25 and 69.22 +/- 2.06 for percent fertility for the duration of fertility. The means of the heritability estimates of the fertility of frozen-thawed and fresh semen, respectively, ranged from .01 to .31 and -.01 to .21. The realized heritability of duration of fertility of frozen-thawed semen, based on five generations, was .17 +/- .05. The phenotypic correlations of duration of fertility of frozen-thawed semen with percent fertility for 2 to 8 days postinsemination and percent fertility for the duration of fertility of frozen-thawed semen were high and positive and correlations between fertility of frozen-thawed and fresh semen were low but positive.
Animals↗
Effect of homologous and heterologous seminal plasma on the fertilizing ability of ejaculated bull spermatozoa assessed by penetration of zona-free bovine oocytes.
The ability of seminal plasma to influence the fertility of ejaculated bull spermatozoa was examined using a sperm penetration assay for zona-free bovine oocytes. Washed, ejaculated spermatozoa from bulls of below (low) or above average (high) fertility were mixed with seminal plasma from the same bull, or with seminal plasma from a bull of contrasting fertility. Treated spermatozoa were stained with different fluorochromes and competed to penetrate oocytes after heterospermic insemination in vitro. Washed spermatozoa exposed to seminal plasma from bulls of high fertility penetrated more oocytes than those spermatozoa mixed with seminal plasma from bulls of low fertility (P < 0.01). Mixing low fertility spermatozoa with high fertility seminal plasma generally improved penetrating ability compared with low fertility spermatozoa mixed with low fertility seminal plasma (P = 0.05). Washed spermatozoa from a bull of low fertility mixed with his own seminal plasma had greater ability to penetrate oocytes than did washed spermatozoa from a bull of high fertility mixed with seminal plasma from a bull of low fertility (P < 0.01). The bias associated with using low fertility seminal plasma from the bull providing the spermatozoa was removed by repeating this experiment using pooled seminal plasma from different subfertile bulls. After combination with pooled seminal plasma from bulls of low fertility spermatozoa from bulls of high or low fertility penetrated oocytes in a similar way, but high fertility spermatozoa had a slightly higher penetration rate (P = 0.12). In conclusion, the penetration of zona-free oocytes by ejaculated spermatozoa from bulls of low fertility was marginally improved by seminal plasma from bulls of high fertility, but penetration by high fertility spermaotoza was decreased by exposure to low fertility seminal plasma. Seminal plasma from bulls of low fertility similarly affected the penetrating ability of high and low fertility spermatozoa if the seminal plasma used was foreign to the spermatozoa being tested.
Animals↗
Fertility awareness and natural family planning.
Information about fertility awareness helps to fulfil the broader definition of the services many family planning clinics offer. Although information about natural family planning is requested by a small number of clients seeking family planning advice, many more clients benefit from information about fertility awareness. Fertility awareness is far more than just basic reproductive anatomy and physiology; fertility awareness involves understanding basic information about fertility and reproduction, being able to apply it to oneself, and being able to discuss it with a partner or with a health professional. Fertility awareness is fundamental to understanding and making informed decisions about reproductive health and sexual health. If clients have a better understanding of fertility awareness, they are in a stronger position to make informed decisions about how they wish to manage their reproductive and sexual health, for example: (1) Fertility awareness information is used to help couples to plan pregnancies as well as to avoid them. This can be helpful to couples who are having difficulty conceiving, for the timing of intercourse or for the timing of some of the sub-fertility investigations. (2) The information is also useful when helping couples to understand how each method of family planning works--how the family planning method interrupts normal fertility, how the method will fail if not used correctly, and how fertility returns when the method is discontinued. (3) Women who are fully breastfeeding value the knowledge about reduced fertility, as do women during the perimenopausal years who value being given clear information about their declining fertility. (4) When counselling couples about the importance of avoiding sexually transmitted diseases it is important they understand sexually transmitted diseases may damage their fertility. (5) Couples who choose only to use a barrier method during the time they think the woman is fertile are a group who do not readily identify themselves to family planning providers. These couples often do not have adequate information about fertility awareness. Advances in technology and the understanding of ovulation, ovum and sperm survival have confirmed that the guidelines used to teach fertility awareness and natural family planning effectively identify the fertile phase of the menstrual cycle. Serial ultrasound studies on the ovaries during the menstrual cycle have confirmed the accuracy of the hormonal assays in pinpointing the likely time of ovulation. Ultrasound studies have also shown that subjective observations of the alterations in cervical mucus and the basal body temperature rise are accurate indicators of the fertile phase. Research on the chances of conception on each day of the menstrual cycle, using hormonal assays to estimate the time of ovulation, was carried out in 1994 by Weinberg and Wilcox. Their results showed that the timing of sexual intercourse, in relation to ovulation, strongly influences the chance of conception. Conception only occurred during a 6-day interval that ended on the estimated day of ovulation. The chances of conception fell to zero 24 hours after ovulation. Several different methods of natural family planning are taught; some methods depend on only using one of the indicators of fertility, others are based on two or more indicators. The main indicators of fertility are: observing the cervical mucus, recording the basal body temperature, palpating the cervix and a calculation based on the cycle length. Research studies performed using a combination of the indicators of fertility show that the failure rate using a combination is less than most of the studies which use a single indicator. In each case the method failure is far lower than the user failure. (ABSTRACT TRUNCATED)
Body Temperature↗
Preliminary results of hemizona assay (HZA) as a fertility test for canine spermatozoa.
The Hemizona assay (HZA) is considered to be an effective test for predicting the fertilizing potential of spermatozoa. It is a functional test that distinguishes the zona-binding capacity of spermatozoa from fertile and infertile males. The objective of this study was to validate the HZA for canine spermatozoa, as a test for diagnosing canine male fertility status. Various parameters that affect binding capacity were examined: the presence of an adequate number of capacitated and motile spermatozoa for an HZA, the influence of fertility status, sperm-binding variability within fertile dogs over 60 d, variability in sperm-binding capacity of different oocytes, the lower limit number of spermatozoa binding to a zona from the fertile control, and evaluation of HZI to determine the fertilizing capacity of spermatozoa. Hemizonae were obtained from frozen oocytes of spayed bitches. The oocytes were manually cut into nearly equal halves. Spermatozoa were capacitated by swim-up and 1 h incubation at 37 degrees C in modified Ham's F10 medium. Spermatozoa and hemizonae were co-incubated in 100-microL drops at 37 degrees C for 1 h. Spermatozoa from 7 fertile and 3 infertile dogs were used for this study. The optimal sperm concentration for hemizona insemination was 1 x 10(6)/mL capacitated and motile spermatozoa. A significant difference (P < 0.001) was found the number of tightly zonabound spermatozoa between fertile and infertile dogs. Although there was a small difference in zona binding capacity between ejaculates of the same fertile dog (44 +/- 18.24), the main cause for the difference mentioned above was that of poor zona pellucida-binding capacity of spermatozoa from infertile dogs. We found a maximum of 14.28% bad oocytes when we compared sperm samples from 3 fertile and 3 infertile dogs in 56 HZA replicates. To avoid the effect of bad zona on sperm binding we calculated 37 (95% CI) bound spermatozoa from infertile dogs in 56 replicates. Thus, an HZA experiment in which a control dog had < 37 zona bound spermatozoa was repeated. Based on a minimum of 37 bound spermatozoa for fertile males (controls), a differential zona-binding capacity and hemizona index (HZI) between fertile and infertile dogs and between 2 fertile dogs was determined. The binding differential between fertile and infertile dogs was 64.92 +/- 24.29, while between 2 fertile dogs it was 22.38 +/- 10.02 (P < 0.001). According to the HZI values, a value equal to or less than 41.11 indicated an infertile test dog, while an HZI value equal to or greater than 57.95 indicated a fertile test dog. Any value between these two could indicate either fertility or infertility. The evaluation of fertilizing potential of spermatozoa can be improved using the HZA protocols described above.
Animals↗
Fertility transition in Bangladesh: understanding the role of the proximate determinants.
Bangladesh has been passing through a crucial phase of fertility transition. The level of fertility declined dramatically during the early 1990s without any remarkable improvement in socioeconomic and health status, and then remained constant at a high level of 3.3, despite the increased use of contraception. Such fertility transition can be traced to variations in one or more of the proximate or direct determinants of fertility. This paper critically analyses the fertility levels in Bangladesh with a view to exploring the possible explanations of fertility decline in the 1990s and then its stabilization. The main focus of the study is to examine the role of the major proximate determinants of fertility in bringing about the change in fertility level in Bangladesh. The data for the study come from a series of nationally representative surveys over the period of 1975 to 1999-2000. The analysis indicates that fertility has temporarily ceased to decline in recent years due to the 'tempo' effect of high past fertility, but in general a declining trend in fertility is underway. The analysis suggests that the fall in fertility is consistent with the underlying trends in most important proximate determinants of fertility. In recent years contraception has emerged as the highest fertility reducing factor in Bangladesh and its effect is greatest in middle and older age groups. Although until the early 1990s postpartum lactational infecundability was the most important and strongest fertility reducing factor in Bangladesh, in recent years its fertility inhibiting effect has gradually decreasing owing to the declining trend in the lactational infecundability period. The analysis reveals that although the fertility reducing effect of the marriage pattern is increasing, its effect is offset by the declining trend in the lactational infecundability period. A review of these two variables suggests that their effect cannot be raised much for prevailing socioeconomic and cultural reasons, and any future reduction in fertility in Bangladesh may be largely dependent on increased use of effective birth control methods.
Adolescent↗
Community structure of ammonia-oxidizing bacteria under long-term application of mineral fertilizer and organic manure in a sandy loam soil.
The effects of mineral fertilizer (NPK) and organic manure on the community structure of soil ammonia-oxidizing bacteria (AOB) was investigated in a long-term (16-year) fertilizer experiment. The experiment included seven treatments: organic manure, half organic manure N plus half fertilizer N, fertilizer NPK, fertilizer NP, fertilizer NK, fertilizer PK, and the control (without fertilization). N fertilization greatly increased soil nitrification potential, and mineral N fertilizer had a greater impact than organic manure, while N deficiency treatment (PK) had no significant effect. AOB community structure was analyzed by PCR-denaturing gradient gel electrophoresis (PCR-DGGE) of the amoA gene, which encodes the alpha subunit of ammonia monooxygenase. DGGE profiles showed that the AOB community was more diverse in N-fertilized treatments than in the PK-fertilized treatment or the control, while one dominant band observed in the control could not be detected in any of the fertilized treatments. Phylogenetic analysis showed that the DGGE bands derived from N-fertilized treatments belonged to Nitrosospira cluster 3, indicating that N fertilization resulted in the dominance of Nitrosospira cluster 3 in soil. These results demonstrate that long-term application of N fertilizers could result in increased soil nitrification potential and the AOB community shifts in soil. Our results also showed the different effects of mineral fertilizer N versus organic manure N; the effects of P and K on the soil AOB community; and the importance of balanced fertilization with N, P, and K in promoting nitrification functions in arable soils.
Ammonia↗
Prospective, auto-controlled study on reinsemination of failed-fertilized oocytes by intracytoplasmic sperm injection.
OBJECTIVE: To evaluate the possible influence of late fertilization after standard IVF on the results of reinsemination of assumed failed-fertilized oocytes by microinjection and to examine the correlation between the effect of aging of (failed-fertilized) oocytes and the ability of these oocytes to become fertilized. DESIGN: Trial 1: Group 1 (injected-day 1), 93 failed-fertilized oocytes injected 1 day after ovum pick-up; group 2 (control), 82 failed-fertilized oocytes with no microinjection performed. Trial 2: Group 1 (ICSI-day 1), 40 failed-fertilized oocytes injected 1 day after ovum pick-up; group-2 (ICSI-day 2), 40 failed-fertilized oocytes injected 2 days after ovum pick-up. In addition, 35 two- to eight-cell stage embryos, obtained after ICSI of IVF failed-fertilized oocytes, were fixed for cytogenetic analysis. MAIN OUTCOME MEASURES: Normal and abnormal fertilization and embryo development. RESULTS: Trial 1: 53% normal (2 pronuclear [PN]) and 25% abnormal (> or = 3PN) fertilization rates were obtained in group 1 (injected-day 1), and 71% of the 2PN and 74% of the > or = 3PN oocytes cleaved with < 50% fragmentation. No pronuclear (> or = 2PN) development occurred in the control group. Trial 2: 45% and 8% normal and 25% and 40% abnormal fertilization rates were obtained, respectively, after ICSI of 1-day-old and 2-day-old failed-fertilized oocytes. Two days after microinjection, 67% and 67% of the 2PN and 80% and 44% of the > or = 3PN oocytes cleaved with < 50% fragmentation in group ICSI-day 1 and in group ICSI-day 2, respectively. CONCLUSIONS: Late fertilization after initial in vitro insemination does not play a role in the high fertilization rate obtained after reinsemination of assumed failed-fertilized oocytes by ICSI. Normal (2PN) fertilization rate, however, decreases strongly and the abnormal (> or = 3PN) fertilization rate increases with oocyte aging and derived embryos seem to have a high incidence of cytogenetic abnormalities.
Cell Nucleus↗
Evaluation of the duration of sperm fertilizing ability in five lines of commercial broiler breeder and Delaware cross males.
The ability to characterize the reproductive potential of male fowl can be affected by a number of factors, including age, type, insemination scheme, and number of sperm inseminated. Fertility is a complex interaction of traits involving two individuals of differing genetic composition: In modern broiler breeders, selected predominantly for growth and carcass characteristics, fertility problems may be exacerbated. In order to evaluate the male components of fertility, an experiment investigating the effects of male line on both average fertility and the duration of fertility was completed. Male chicks from five commercial broiler breeder male lines or sired by subfertile Delaware cross roosters were reared to adulthood. Between 30 and 60 wk of age, semen was collected from five males per line, extended and used to inseminate each of 10 to 12 hens from four broiler breeder female lines or Single Comb White Leghorn hens with 80 x 10(6) live sperm. Following a single insemination eggs were collected for 21 d and fertility determined by visual inspection following 4 d incubation. The percentages of live sperm and overall fertility data for the replicate trials were analyzed, following transformation, with a linear model and daily fertility data were analyzed by iterative least squares regression. Whereas there were large differences in fertility among individual males (durations from 3.4 to 14.5 d) within a line, there were no significant male line or replicate effects on overall fertility or the duration of fertility. However, there was a significant (P < 0.05) line-dependent reduction in the percentage of live sperm in broiler breeder males, with the subfertile Delaware cross males being intermediate. There were no significant female line or replicate effects on the duration of fertility; however, there were significant female line effects on overall fertility at both 7 and 21 d. These data suggest that although individual males varied widely, there were no male line effects on the duration of fertility in the lines of broiler breeders evaluated when analyzed by iterative least squares. Furthermore, these data suggest that although females may have significant affects on overall fertility, the duration of fertility appears to be a predominantly male characteristic. Therefore, iterative least squares regression may be a useful tool for identifying males with superior sperm fertilizing ability.
Animals↗
Semen profile, testicular volume, and hormonal levels in infertile patients with varicoceles compared with fertile men with and without varicoceles.
OBJECTIVE: To assess semen analysis, testicular volume, and hormone levels in fertile and infertile patients with varicoceles and fertile men without varicoceles. DESIGN: Retrospective study. SETTING: Academic medical center. PATIENT(S): Patients were divided into three groups: fertile men with varicoceles (n = 79), infertile men with varicoceles (n = 71), and fertile men without varicoceles (n = 217). INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): Levels of LH, FSH, and total T and testicular volume in fertile and infertile men with varicoceles and fertile controls without varicoceles. RESULT(S): LH (IU/L) and T (ng/dl) levels were not statistically different across the three groups. FSH levels were significantly higher in infertile men with varicoceles (7.8 +/- 7.6 IU/L) than in the fertile men with varicoceles (3.5 +/- 2.1 IU/L) or in fertile men without varicoceles (3.5 +/- 1.9 IU/L). The right testicle was smaller in infertile patients with varicoceles (18.7 +/- 8.3 cm(3)) than in fertile men with varicoceles (25.2 +/- 13 cm(3)) or in fertile men without varicoceles (24.9 +/- 10.7 cm(3)). In addition, the left testicle was smaller in infertile men with varioceles (17.6 +/- 8.9 cm(3)) than in fertile men with varicoceles (21.6 +/- 7.8 cm(3)) or in fertile men without varicoceles (23.4 +/- 8.3 cm(3)). Sperm concentration was lower in infertile men with varicoceles (33.7 +/- 23.3 x 10(6)/mL) than in fertile men with varicoceles (101.8 +/- 76.6 x 10(6)/mL) or in fertile men without varicoceles (111.8 +/- 74.2 x 10(6)/mL). In addition, sperm motility was lower in infertile men with varicoceles (37.2% +/- 23.9%) than in fertile men with varicoceles (53.9% +/- 17.4%) or fertile men without varicoceles (58.9% +/- 15.8%). CONCLUSION(S): Infertile patients with varicoceles have higher levels of FSH, smaller testes, and lower sperm concentration and motility compared with controls with or without varicoceles. No statistical differences were seen in the variables evaluated among the fertile men with incidental varicoceles detected at physical examination and those without varicoceles.
Adult↗
Treatment of male infertility and idiopathic failure to fertilize in vitro with under zona insemination and direct egg injection.
OBJECTIVE: Failure to fertilize eggs in vitro may be countered by micromanipulation of gametes to place selected spermatozoa underneath the zona pellucida of the egg or directly into the egg, thereby improving chances of fertilization and production of viable embryos. Analysis of our clinical data for assisted fertilization was undertaken to assess those factors of relevance in this therapy, and a description of our procedures are given. STUDY DESIGN: Retrospective analysis of 85 cycles (73 couples) of in vitro fertilization and embryo transfer performed at a private infertility clinic, in which micromanipulation for assisted fertilization was used to overcome either severe male factor infertility or idiopathic failure to fertilize, was performed. RESULTS: In 60 cycles where only embryos from under zona insemination were available for uterine transfer, 15 singleton and two twin pregnancies occurred (28.3% viable pregnancy rate per transfer, 14.1% embryonic implantation). In 14 of these cycles embryos arose only after repeated under zona insemination adding more spermatozoa; this accounted for four of the singleton and one of the twin pregnancies (38.5% pregnancy rate, 22.2% embryonic implantation). No embryos arose from partial zona dissection performed in five cycles on sibling eggs. However, in 16 cycles conventional insemination yielded fertilization in six cycles, and mixed transfer of these embryos and sibling embryos from under zona insemination gave rise to one pregnancy from four transfers (pregnancy rate 25%, embryonic implantation 7.1%). Likewise, in nine cycles donor spermatozoa yielded fertilization in eight cycles, and mixed transfer with sibling embryos fertilized by under zona insemination with partner's spermatozoa gave rise to two pregnancies from five transfers (pregnancy rate 40%, embryonic implantation 15.8%). Fertilization and pregnancy rates did not differ whether couples suffered either from male factor infertility or from previous idiopathic fertilization failure. Direct egg injection of a single spermatozoon into 105 eggs gave an 88.6% egg survival and 32.3% fertilization. Mixed transfers with sibling embryos from conventional and under zona insemination yielded one triplet, one twin, and three singleton pregnancies. CONCLUSIONS: Overall, a 24.7% (21/85) viable pregnancy rate per cycle initiated occurred when only embryos from assisted fertilization were available. This strongly indicates that assisted fertilization made a real contribution in cases where either insufficient spermatozoa were available for conventional insemination or in cases where previous fertilization failure had arisen. The wide range of seminal parameters were found to be unhelpful in defining chances of success with assisted fertilization.
Female↗
Poor implantation of cryopreserved reinsemination-fertilized human embryos.
OBJECTIVE: To investigate whether a poor rate of implantation after in vitro fertilization (IVF) was due to poor embryonic/endometrial synchrony during the original IVF cycle, we have cryopreserved reinseminated-fertilized embryos for later more synchronous replacement after thawing. The chance of implantation of fresh reinseminated fertilized human oocytes is approximately one tenth that of timely fertilized embryos. STUDY DESIGN AND DATA: Retrospective study of 35 original oocyte collections in which initial normal fertilization was 47.3% (129/273 oocytes), with 49.6% fertilization (67/135) upon reinsemination. Of these, 70 initially fertilized and 67 reinsemination-fertilized embryos were cryopreserved, and 50 initially fertilized and all 67 reinsemination-fertilized embryos were subsequently thawed with 72% and 63% cryosurvival, respectively, (not significant). SETTING: Private infertility clinic. RESULTS: In 11 cycles, 23 thawed initially fertilized embryos (group A) were replaced with a 21.7% implantation rate per embryo; in 10 cycles, 13 initially fertilized and 12 reinsemination-fertilized embryos (group B) were replaced together with an 8% implantation rate; finally, in 16 cycles, 30 reinsemination-fertilized embryos (group C) were replaced with a 3.3% implantation rate (group A versus group C: P = 0.076). Comparison of clinical pregnancies between these groups was significantly different (6/11 versus 1/16; P = 0.0427). CONCLUSION: Reinsemination-fertilized embryos survive freezing as well as initially fertilized embryos, but better embryonic/endometrial synchrony does not improve chances of their implantation.
Adult↗
Fertility-associated proteins in Holstein bull seminal plasma.
This study was undertaken to determine whether bovine seminal plasma contained protein markers associated with bull fertility, and whether these markers were of value in predicting bull fertility. Seminal plasma was obtained from 35 Holstein bulls of known fertility. Two-dimensional PAGE of seminal plasma samples indicated that two proteins (26 kDa, pI 6.2; 55 kDa, pI 4.5) predominated in higher-fertility bulls, and two proteins (16 kDa, pI 4.1; 16 kDa, pI 6.7) predominated in lower-fertility bulls. Densitometry data for these proteins in individual samples were combined for bulls grouped by fertility level. Average density of the 26-kDa protein was significantly greater in seminal plasma of high-fertility bulls, and high-fertility seminal plasma also contained more of the 55-kDa protein than that of average- and below average-fertility bulls. Below average- and low-fertility bull seminal plasma had significantly more of both 16-kDa proteins than that of average- and high-fertility bulls. A regression model was developed to predict bull fertility using the four fertility-associated protein densities. A plot of actual bull fertility versus that calculated by this model was linear and positively correlated (r = 0.89). These findings indicate that bull seminal plasma contains fertility-associated proteins that are predictive of bull fertility.
Animals↗
The urodele egg-coat as the apparatus adapted for the internal fertilization.
Fertilization is a significant event for reproducing offspring. It is achieved under a species-specific environment, which influences the conditions to assure the successful fertilization in some cases. Several studies about the basic mechanism of fertilization suggest that the fertilization mechanism is modified among species to be suited for the fertilization environment. In amphibians, many anurans undergo external fertilization while most urodeles do internal fertilization. An amphibian egg is surrounded by egg-coats, which are composed of vitelline envelope and layered egg-jelly. They are significant as fields for the sperm-egg interaction at fertilization. The fertilization processes that take place in the egg-coats are supposed to be easily influenced by the fertilization environment, because they, especially egg-jelly, are exposed to the surroundings at fertilization. In the present article, we describe the fertilization system equipped in newt egg-coats. Newt sperm are stored in spermatheca that exists in cloaca of a female and directly inseminated on the surface of egg-jelly. Sperm motility and acrosome reaction are induced in the outermost portion of the egg-jelly. Motion of the moving sperm becomes vigorous in the egg-jelly and sperm are guided to vitelline envelope by the aid of egg-jelly structure. Most of the sperm passing through the egg-jelly, as the result, has been induced acrosome reaction and those sperm can bind to the vitelline envelope to contribute to the successful fertilization. This fertilization system has a distinct feature from the known system in species undergoing external fertilization. The feature of the system in the newt egg-jelly is discussed with the view to achieving the successful fertilization in the internal environment.
Adaptation, Physiological↗
[Tempo and parity structure of Japanese fertility].
The present study is part of a larger project on the formal demographic analysis of Japanese fertility. It deals with the most elusive aspect of fertility, that is the tempo of fertility. The temporal aspect of fertility, particularly in terms of cohort fertility framework with speical reference to parity of women, has been emphasized by Whelpton and Ryder, but in the Japanese demography there have scarcely been studies of this aspect, probably due to lack of interest. In very recent years, however, interest has grown, reflecting the need for more accurate fertility projections in the future in connection with population projections. The present study is an application of life table techniques to explore the temporal aspect of fertility in Japan. 2 methods have been used. One is the age-marriage-parity specific net reproduction rate tables, which were first constructed by the senior author of this paper. The other is by Professor Chin Long Chiang at the University of California, Berkely. In the application of the former type, net reproduction rate tables were constructed for 3 dates -- 1970-71, 1975-76, and 1980-81. Through this method, it was demonstrated that recent fertility for the period 1980-81 was reduced, partly because of the decline in fertility in live-birth order of 1 and 2 among the relatively young ages up to 25 years old. On the other hand, for the ages up to 30 years old, some catching-up mechanisms took place. The 2nd method is by Chiang's new approach to the fertility table. According to his method, which was included in his new book entitled Life Tables and Its Applications, parity-oriented fertility tables have been constructed for the Japanese females for every year from 1971 through 1983, both inclusive. In these cases, denominator is for year z while numerator is concerned with yea z + 1. This method is particularly interesting since it can calculate waiting time for childbearing until the completion of family formation. Some of the findings indicated: 1) recent increases in both parity progession ratio and parity-specific fertility rate in low parity augur a future increase in fertility in the period measure in the near future; and 2) a shortening of the waiting time until the completion of family formation around 1981 and then the recovery of its lengthening in the years 1982 and 1983 suggest a recent trend of lengthening actual reproductive period which definitely contributes to an increase in fertility.
Asia↗
Intracellular Ca2+ increase induces post-fertilization events via MAP kinase dephosphorylation in eggs of the hydrozoan jellyfish Cladonema pacificum.
Naturally spawned eggs of the hydrozoan jellyfish Cladonema pacificum are arrested at G1-like pronuclear stage until fertilization. Fertilized eggs of Cladonema undergo a series of post-fertilization events, including loss of sperm-attracting ability, expression of adhesive materials on the egg surface, and initiation of cell cycle leading to DNA synthesis and cleavage. Here, we investigate whether these events are regulated by changes in intracellular Ca2+ concentration and mitogen-activated protein kinase (MAP kinase) activity in Cladonema eggs. We found that MAP kinase is maintained in the phosphorylated form in unfertilized eggs. Initiation of sperm-induced Ca2+ increase, which is the first sign of fertilization, was immediately followed by MAP kinase dephosphorylation within a few minutes of fertilization. The fertilized eggs typically stopped sperm attraction by an additional 5 min and became sticky around this time. They further underwent cytokinesis yielding 2-cell embryos at approximately 1 h post-fertilization, which was preceded by DNA synthesis evidenced by BrdU incorporation into the nuclei. Injection of inositol 1,4,5-trisphosphate (IP3) into unfertilized eggs, which produced a Ca2+ increase similar to that seen at fertilization, triggered MAP kinase dephosphorylation and the above post-fertilization events without insemination. Conversely, injection of BAPTA/Ca2+ into fertilized eggs at approximately 10 s after the initiation of Ca2+ increase immediately lowered the elevating Ca2+ level and inhibited the subsequent post-fertilization events. Treatment with U0126, an inhibitor of MAP kinase kinase (MEK), triggered the post-fertilization events in unfertilized eggs, where MAP kinase dephosphorylation but not Ca2+ increase was generated. Conversely, preinjection of the glutathione S-transferase (GST) fusion protein of MAP kinase kinase kinase (Mos), which maintained the phosphorylated state of MAP kinase, blocked the post-fertilization events in fertilized eggs without preventing a Ca2+ increase. These results strongly suggest that all of the three post-fertilization events, cessation of sperm attraction, expression of surface adhesion, and progression of cell cycle, lie downstream of MAP kinase dephosphorylation that is triggered by a Ca2+ increase.
Animals↗
Slow fertilization of stickleback eggs: the result of sexual conflict?
BACKGROUND: The fertilization success in sperm competition in externally fertilizing fish depends on number and quality of sperm. The time delay between sequential ejaculations may further influence the outcome of sperm competition. Such a time interval can load the raffle over fertilization if fertilization takes place very fast. Short fertilization times are generally assumed for externally fertilizing fish such as the three-spined stickleback (Gasterosteus aculeatus). In this pair-spawning fish, territorial males often try to steal fertilizations in nests of neighbouring males. This sneaking behaviour causes sperm competition. Sneakers will only get a share of paternity when eggs are not fertilized immediately after sperm release. Contrary to males, females may be interested in multiple paternity of their clutch of eggs. There thus may be a sexual conflict over the speed of fertilization. RESULTS: In this study we used two different in vitro fertilization experiments to assess how fast eggs are fertilized in sticklebacks. We show that complete fertilization takes more than 5 min which is atypically long for externally fertilizing fishes. CONCLUSION: This result suggests that the time difference does not imply high costs to the second stickleback male to ejaculate. Slow fertilization (and concomitant prolonged longevity of sperm) may be the result of sexual conflict in which females aimed at complete fertilization and/or multiple paternity.
Animals↗
Sperm survival and heterogeneity are correlated with fertility after intrauterine insemination in superovulated ewes.
Efficient animal production involves accurate estimations of fertilizing ability. One key factor is the plasma membrane of the sperm cell, which is actively involved in the cascade of events before oocyte fusion. Many methods are used to analyze the characteristics of this membrane, including partition in aqueous two-phase systems which is an efficient method to analyze sperm surface changes accounting for loss of viability and different functional states. Centrifugal countercurrent distribution (CCCD) analysis can also be used in an aqueous two-phase system to determine the relationship between sperm parameters and in vivo fertility in ewes. In a previous work, we found a significant correlation between two post-CCCD parameters (heterogeneity and recovered viability) and field fertility when the same sample was used after cervical AI. The present study was intended to find out whether the control of several external factors that affect reproductive efficiency is able to increase the correlation coefficient between post-CCCD parameters and fertility. Thus, 90 Rasa aragonesa ewes were controlled on the same farm and received intrauterine inseminations using the same technical equipment. The fertilizing ability of the raw semen and sperm samples selected by a dextran/swim-up process was compared using a low number of spermatozoa per insemination (7 x 10(7)) to enhance possible fertility differences. A new post-CCCD parameter was considered; the loss of viability (LV) occurred during the CCCD process. This variable denotes the sperm surviving ability and corresponds to the difference between the total number of viable cells loaded and recovered after the CCCD run. The mean fertility of eight sperm control samples was 60% (range: 25-76%), and there was no significant correlation between standard parameters and in vivo fertility. LV ranged from 2 to 69% (average 27%) and was negatively correlated with fertility (r = -0.914, P < 0.01). Ejaculate heterogeneity (H) ranged from 20 to 47% and was positively, but not significantly, correlated with fertility (r = 0.391). A predictive equation for fertility was deduced by multiple analysis with a very high correlation coefficient (r = 0.967), and level of significance (P < 0.005): predictive fertility PF = 52.546 - 0.594 LV + 0.665 H. The mean fertility of 13 swim-up selected samples was 63% (range: 25-86%). Again, only parameters derived from the CCCD analysis were highly correlated with fertility, especially LV and H (P < 0.05).
Animals↗