The Hormonal Induction of Ovulation or of Luteinization in the Intact or Hypophysectomized Guinea-Pig

Abstract

The induction of ovulation and follicular luteinization in the guinea-pig by follicle-stimulating (FSH) and luteinizing (LH) hormones was studied in the intact and in the hypophysectomized animal. Follicular luteinization could be produced as early as day 8 of the oestrous cycle by 250 mu. FSH, but not before day 10 by 400 mu. LH, while either FSH or LH caused ovulation when given on day 12 or later. When injected on day 13, luteinization could be induced with 62\m=.\5mu. FSH or 200 mu. LH. Luteinization of follicles also occurred when 400 mu. LH or 250 mu. FSH was given immediately after hypophysectomy on day 13, but when hormone treatment was delayed for 4\m=.\5h after surgery the incidence of luteinization was greatly reduced. Combined treatment with 200 mu. LH and 125 mu. FSH, by contrast, readily caused luteinization. It is concluded that ovarian follicles are resistant to luteinization during the first half of the oestrous cycle and that the response to LH late in the cycle is dependent upon the maintenance of follicular responsiveness by endogenous gonadotrophin.

Effects of Gonadotropins on Follicular Development, Ovulation, and Atresia in the Mature Guinea Pig

“…Perry and Rowlands (1963) studied the effects of a number of gonadotropins in the hypophysectomized, immature guinea pig without finding a successful method to produce ovulation or corpus luteum formation. Although the successful induction of ovulation in the mature guinea pig has been reported following the administration of ovine luteinizing hormone (LH) (Dempsey et al, 1936;Deanesly, 1966;Reed and Hounslow, 1971;Donovan and Lockhart, 1974), there have been no reports of reliable ovulation induction in the cycling guinea pig in response to HCG. Quinn (1970) examined the ovarian response 18-19 h after subcutaneous injection of various doses of HCG in guinea pigs but did not quantitate follicular changes in detail and did not observe consistent ovulation induction.…”

The Role of Pheromones in the Regulation of Estrous Cycle Duration in the Guinea Pig

“…Follicular rupture is strictly dependent on ovarian follicular sensitivity to gonadotrophins [Jesel, 1969[Jesel, , 1971Reed, 1969;Donovan and Lockhart, 1974]; accordingly, it may be supposed that the pheromone-induced acceleration of follicular growth (loc. cit.)…”

Optimization of superovulation induction by human menopausal gonadotropin in guinea pigs based on follicular waves and FSH‐receptor homologies

“…Normally, guinea pigs ovulate only a few oocytes (3.6 AE 0.1), as judged by the number of corpora lutea (CL) (Suzuki et al, 1993). Interestingly, injections of equine chorinonic gonadotropin (eCG) and human chorinonic gonadotropin (hCG), which are often used to induce superovulation in mice, are not effective in guinea pigs (Reed and Hounslow, 1971;Donovan and Lockhart, 1974). Only a few other methods have been reported for the induction of superovulation, including treatment with luteinizing hormone (LH) (Terranova and Greenwald, 1981) or anti-LH (Garza et al, 1984).…”