Fertilization of the Mouse Egg and the Effect of Delayed Coitus and of Hot-Shock Treatment

Abstract

A total of 329 mated adult mice was used in the investigations. The mean number of eggs per mouse recovered from 171 mice killed 3-15 hr after ovulation was 8·10 (S.D. 1·94).In mice maintained under conditions of controlled illumination (light from 3, to 5 a.m., dark from 5 a.m. to 3 p.m.) ovulation began about 11 a.m. and was virtually complete by 4 p.m. The average interval between the ovulation and sperm penetration of an egg was about 5 hr. The sperms spent a mean time of about 35 min in the perivitelline space before entering the vitellus; after a further mean interval of about 2% hr the early pronuclei were seen.The mean delay between the beginning of ovulation and the beginning of sperm penetration, in anyone mouse, was 2*-3 hr. The mean time required for the majority (~%) of the eggs in anyone mouse to be penetrated by sperms, once penetration had begun, was 3Jf.-4 hr. A mean number of 18·6 sperms per tube was found at the site of fertilization shortly after ovulation.Mice kept under natural lighting conditions were not permitted coitus until 8-8.45 a.m. Sperm penetration of the eggs began between 9 and 9.30 a.m. Once penetration had begun, the average period required for the penetration by sperms of at least three-quarters of the eggs in anyone mouse was about 2 hr. The mean number of sperms at the site of fertilization at 9, 9.30, and 10 a.m. was 6·3, 7·9, and 20·6 sperms per tube, respectively. These findings are discussed in relation to the concept that sperms need to spend a period in the female tract to capacitate them for the penetration of the eggs.The incidence of polyspermy in mouse eggs was not increased by delaying coitus until 3-7 hr after ovulation.Hot-shock treatment applied to the eggs of mice 3 hr after mating increased the incidence of polyspermy (dispermy) from 0·3 to 3·8 per cent. and of eggs exhibiting suppression of the second polar body from 0·5 to 12·4 per cent. Several other forms of abnormal fertilization were also observed. It is considered that the triploidy reported in mouse embryos following hot-shock treatment of the eggs probably arose in most instances through suppression of second polar body formation, and only occasionally through polyspermic fertilization.

A polycystin-1 controls postcopulatory reproductive selection in mice

“…Males were given access to wild-type females for 2-h time windows, either 7-9 h or 9-11 h after hCG. Mouse sperm require a mean time of 1 h to reach the site of fertilization in the ampulla of the oviduct (27). Thus, mating during the first time window resulted in sperm that arrived in the oviduct before the entry of eggs, whereas in the second window, these events occurred at approximately the same time.…”

“…Mouse sperm require Ϸ1 h to reach the site of fertilization in vivo (27) (Fig. 4) and to develop ZP responsiveness in in vitro assays (Fig.…”

Differing requirements for capacitation in vitro of mouse spermatozoa from two strains

“…If capacitation occurs in the mouse, it is a relatively rapid process in vivo, because when mating is delayed until ovulation is completed sperm penetration can be detected as early as 1 h after mating (Braden & Austin, 1954;Bryan, 1974;Krzanowska, 1964). Various studies, employing a variety of media and strains of mice, have suggested that capacitation in vitro of mouse spermatozoa requires 1-3 h (Hoppe & Whitten, 1974;Iwamatsu & Chang, 1969,1970Miyamoto &Chang, 1973;Oliphant & Brackett, 1973;Toyoda, Yokoyama & Hosi, 1971).…”

The variances of the distributions of the combinations of the sexes within mammalian litters: Notes to mark the centenary of the problem

“…rats, rabbits and mice, the zygotes are not all formed simultaneously but across a period of time Braden and Austin 1954). So I suggest that Gini's speculation does seem implausible indeed.…”