In vitro ovulation from adult hamster ovary.

The purpose of the study was to achieve in vitro ovulation in order to acquire corpora lutea in vitro at "time zero" of their formation. Such in vitro corpora lutea would later be the subject of studies on maintenance and lysis of corpora lutea in vitro. Ovaries from adult hamsters, explained into chemically defined medium between 23:00 hours on the day of proestrus and 01:00 hours on the day of estrus, were examined in the culture medium at 10:00 hours on the day of estrus i.e., after 9 to 12 hours of incubation. Ovulated follicles (young corpora lutea) of differing stages of corpus luteum formation were observed in some of the explants, but not at all. Almost all ovulated ova, surrounded by their cumuli oophori, remained adherent to the area of rupture when the incubation was ended. In vitro ovulation occurs in chemically defined medium without added hormones. It is possible to obtain corpora lutea in vitro at "time zero" of their formation.