Effect of luteinizing hormone on progesterone secretion in vitro by the granulosa cells of the domestic fowl (Gallus domesticus).

During short periods of incubation (3 h) the secretion of progesterone by granulosa cells from the largest preovulatory follicle of the fowl was higher (160 pmol/micrograms DNA) with ovine LH in the medium than without it (60 pmol/micrograms DNA). Granulosa cells from follicles collected 24 and 48 h before their expected ovulation secreted progesterone at similar rates to cells from the largest follicle which was likely to ovulate within 5 h. The identity of progesterone was confirmed by physicochemical methods. After granulosa cells had been incubated with LH in Medium 199 for 24 h, the concentration of progesterone in the medium was 1.65 mumol/l whereas oestrone and oestradiol were present at concentrations of 254 and 199 pmol/l respectively. The results indicate that the larger yellow yolk-filled follicles of the ovarian hierarchy in the domestic fowl contribute to the preovulatory surge of progesterone which has been observed in the peripheral blood.