Pharmacological action:chorionic gonadotropin is a hormone of human pregnancy- it is secreted by the syncytiotrophoblast of foetal placenta as early as 7 days after ovulation, and it is absorbed into the blood in sufficient quantity to sustain luteal function and forestall the next menstrual period. the secretion of lh therefore remains suppressed because of the rising concentrations of oestrogen and progesteroneindications:in the female:1. infertility - ovulation induction: a.p.l. is used in the induction of ovulation after the carefully monitored stimulation of follicular maturation with either human menopausal gonadotrophins (hmg) or clomiphene citrate.in the male:2. cryptorchidism not due to anatomic obstruction. a.p.l. may also be used (a) as a diagnostic aid to determine the need for surgery- (b) pre-operatively, with a view to facilitating the procedure by increasing the size of the testes and the length of the cords.