Fertilization in vitro of cumulus-enclosed mouse oocytes: effect of timing of the ovulatory HCG injection.

Human chorionic gonadotropin (HCG) may be injected to time ovulation and plan oocyte retrieval for clinical in vitro fertilization (IVF). Neither clinical nor experimental data on effects of subtle alterations in timing of the HCG injection on oocyte fertilizability in vitro were available. We induced follicular development in immature hybrid mice with an injection (4 IU) of pregnant mare serum gonadotropin (PMSG). In the first series of experiments, HCG was given 42, 46 or 50 hours later. We collected cumulus-enclosed, oviducal oocytes for IVF using capacitated mouse sperm 13 hours after the last HCG injection. The fertilization incidence (mean, three experiments) fell as the PMSG-HCG interval was reduced (50 hours, 64%; 46 hours, 40%; 42 hours 24%), but this could be explained by a corresponding increase in spontaneous oocyte activation caused by prolonging the HCG-oocyte collection interval. In the second series of experiments, the latter was fixed at 13 hours; the PMSG interval was altered by staggering the initial PMSG injection. No spontaneous activation occurred, but oocytes collected after "early" HCG injection still showed significantly lower fertilization incidences (42 hours, 36%; 46 hours, 46%) compared with the 50-hour injection (66%). The possible clinical implication of this finding is discussed.

Effects of age, parity and length of pregnancy on the morphology and histology of human placenta.

A great majority of death-in-utero in this country may be due to placental insufficiency. This problem may have some correlation between parity, maternal age and weight of placenta. The present work has been attempted towards determination of the morphological and histological aspect of human full-term placentae and their relation with different parity and age group of mothers. The weight, size and number of cotyledons of placentae were found to be directly proportional to the maternal age and parity. No definite change in histology was observed except for the increase in fibrinoid degenerations in the stem villi and calcium deposition on the septal region of the placentae. These changes may have some important bearing on the placental insufficiency in higher age group and parity of mother.

Effect of a single maximal and low multiple doses of testosterone propionate (TP) on male reproductive organs in Long Evans rats.

Testosterone as a male contraceptive agent was tried on two age groups of rats of Long-Evans strain and with two dosage schedule. A general increase in accessory organs weights like seminal vesicle and ventral prostate was observed in all groups of animals with all dosage schedule. The testicular weight was reduced particularly in low multiple dosage group. Gross atrophy with marked irregularity in germ cell pattern and population, suppression of spermatogenesis and atrophy of Leydig cells in the testis of low multiple dosage group were evident without affecting the potentiality to sex drive. A further study is suggested to examine the time period needed for testicular recovery and return of normal spermatogenesis before its possible trial on male volunteers in Bangladesh.

The use of periovulatory human cervical mucus in human sperm capacitation and in-vitro fertilization of foreign eggs.

The time requirement of a routine in-vitro fertilization experiment using human spermatozoa and zona-free hamster oocytes is more than one working day. We have used a simple process of simultaneous sperm washing and capacitation before challenging them against oocytes. Spermatozoa were recovered up to 90 minutes from the proximal end of a column of periovulatory human cervical mucus into Brinster, Whitten and Whittingham's (B.W.W.) medium. Without any further capacitation 50 microliters of these spermatozoal suspension, in the concentration of 2.5-3 X 10(6)/ml, fertilized 81% of a total of 100 eggs. A dramatic decrease in the fertilization rate (18%) was observed when these spermatozoa were further capacitated in-vitro for five hours before actual egg incubation for three hours. Both selection and accelerated capacitation may contribute to this result.

In-vitro fertilization in the mouse and the relevance of different sperm/egg concentrations and volumes.

The sperm:egg ration and sperm concentration were varied separately by using different volumes (1--100 microliters) and egg numbers (1--15). The % fertilization was determined by sperm concentration in large volumes (10--100 microliters). In small volumes (1 or 5 microliters) the number of spermatozoa/egg determined penetration rate: the effective epididymal sperm number/fertilization was 250--350. Spermatozoa obtained from the oviducts (i.e. naturally selected) gave good fertilization responses and low concentrations of epididymal spermatozoa were also more effective when oviducal fluid and cumulus cells were included in the inseminating volume. We conclude that sperm/egg collision rate is the most important factor determining % fertilization, although heterogeneity of epididymal spermatozoa limits fertilization rate at low sperm:egg ratios.