Effect of PMSG on follicular atresia in the immature rat ovary.
Administration of PMSG to 26-day-old rats did not increase the total number (non-atretic and atretic) of preantral (Type 4) and antral (Types 5 and 6) follicles but changed the proportion between non-atretic and atretic follicles. By 12 h after PMSG administration only 7% of Type 5 follicles were atretic, and no atretic follicles of Type 6 were observed, as compared to 52 and 62% atretic follicles, respectively, in the saline-treated controls. PMSG did not decrease the percentage of atresia in preantral (Type 4) follicles. The treatment was associated with a sharp fall by 12 h in the pyknotic index of antral (Types 5 and 6) follicles. It is concluded that PMSG causes superovulation in the rat by rescuing follicles of Types 5 and 6 from atresia and allowing them to reach ovulation.
D000818:Animals; D005260:Female; D006064:Gonadotropins, Equine / Q000494:pharmacology*; D006080:Ovarian Follicle / Q000187:drug effects* / Q000254:growth & development; D051381:Rats; D012741:Sexual Maturation
D006064:Gonadotropins, Equine