The Effect of Massive Doses of Corticotrophin and of Corticosterone on Ovulation of the Chicken (Gallus Domesticus)

One hundred IU of corticotrophin causes premature ovulation in the laying hen. The effect is not due to LH contamination. Corticosterone at levels of 0.5, 1.0 and 5.0 mg/hen does not induce or block ovulation. Ten mg corticosterone/hen causes blocked as well as premature ovulations whereas 20 mg/hen consistently blocks spontaneous as well as progesterone-induced ovulation if given one hour prior to the progesterone. The same level of corticosterone fails to block progesterone-induced ovulations if given simultaneously with the progesterone. The possible mechanisms involved in these phenomena are discussed.