The Effects of Purified Sheep Luteinizing Hormone on the Guinea-Pig Ovary

Abstract

Luteinizing hormone (Ovine, from the National Institutes of Health, Bethesda, U.S.A.) has been administered subcutaneously in normal saline (0\m=.\5mg/ml) to female guinea-pigs for a study of The induced and cyclic corpora lutea were examined in three females killed 7 days after the lh injection given on luteal Day 7; the two types were histologically distinguishable. In one female both sets of corpora lutea had regressed and the follicles were pre-ovulatory. In another, both sets still looked large and healthy and in the last the cyclic corpora lutea were shrunken and vacuolated while the induced corpora lutea, in marked contrast, retained eosinophil luteal cells with numerous mitotic figures.303

Luteolytic Effect of Oestrogen on the Corpora Lutea of the Cyclic Guinea-Pig

“…It has also been suggested that oestrogen may be inducing luteal regression in pregnant guinea-pigs by affecting pituitary gonadotrophic secretions (Deanesly, 1963). It is unlikely that the luteolysis induced by oestrogen in our study involved a stimulation or inhibition of lh secretion, since this hormone has neither luteotrophic nor luteolytic effect in the cyclic guinea-pig (Deanesly, 1966). Oestrogen exerts a luteolytic and an anti-folliculotrophic effect in the hamster.…”

“…Oestrogen exerts a luteolytic and an anti-folliculotrophic effect in the hamster. These effects can be reversed by suitable doses of pmsg, hcg or fsh, but not lh (Greenwald, 1965 (Aldred et al, 1961;Rowlands, 1962;Deanesly, 1966) were unsuccessful. However, fsh was not used in these studies.…”

Independent Regression of Normal and Induced Corpora Lutea in Hysterectomized Guinea-Pigs

“…Up to 56 days after hysterectomy, the original corpora lutea were still of maximum normal size in five out of seven hysterectomized guinea-pigs, in which treatment with lh had induced fresh corpora lutea 7 to 18 days earlier (Deanesly, 1966). In the other two females, 36 and 52 days after hysterectomy, the original corpora lutea were not up to full size, but this probably represented normal variation rather than the effects of induced ovulations.…”

“…In preliminary experiments, this has been shown for both the cyclic and hysterectomized guinea-pig (Deanesly 1966). In the pig (Neill & Day 1964), if the new corpora lutea were not induced very early in the cycle, they survived the original corpora lutea for about one cycle length and prolonged the luteal phase.…”

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.…”