Gonadotropin Consumption Research Articles

Can reduced consumption of gonadotrophins account for ovarian compensation in unilaterally ovariectomized, immature mice injected with gonadotrophins?

The effect of unilateral ovariectomy on ovulation rates in immature mice was studied. Ovulations were induced by injecting PMSG and hCG and their number was determined by counting tubal oocytes. A 2--3-fold increase in number of ovulations per ovary was observed after unilateral ovariectomy, and daily injections of progesterone abolished this ovulatory compensation. No significant increase in serum concentrations of immunoreactive FSH and LH was observed at 4, 8, 32 and 51 h after unilateral ovariectomy. Progesterone treatment lowered FSH levels at all times, while LH was unaffected. In intact mice, ovarian sensitivity to PMSG and hCG was not substantially affected by progesterone. Ovulatory compensation in immature gonadotrophin-injected mice appears to arise through a negative feedback mechanism and transiently increased secretion of pituitary gonadotrophin rather than through a greater utilization of a fixed amount of gonadotrophin.

Mechanism of ovarian control of hypophyseal gonadotrophic function in guinea pig; experiments with intrasplenic grafts.

SummaryHemorrhagic follicles in intra-splenic ovarian grafts in castrated guinea pigs appear irrespectively whether one or 2 ovaries are grafted into the spleen. On the contrary, hemorrhagic follicles fail to appear in an intrasplenic graft of the castrated guinea pig when the second ovary is grafted into the kidney. These experiments give definite evidence that the ovarian control of the hypophyseal gonadotrophic function depends not only, if at all, on consumption of gonadotrophins but certainly also on ovarian hormones which reach the general circulation.