THE STIMULATING ACTION OF COLCHICINE ON PITUITARY-INDUCED OVULATION OF THE FROG

¹ Departments of Pharmacology and Physiology, Dalhousie University, Halifax, N. S.

1. Colchicine in concentrations of 10^–3, 10^–4, 5 x 10^–5, 10^–5, 5 x 10^–6 and 10^–6 potentiated the effect of pituitary in causing ovulation in the isolated frog's ovary. 10^–2 colchicine inhibited ovulation. 10^–7 and 10^–8 solutions were without effect.

2. Papaverine and adrenaline inhibited pituitary ovulation in the excised ovary. Acetyl choline with eserine, and acetanilid failed to modify the pituitary effect.

3. Ovulation by injected pituitary in the intact animal was augmented by the simultaneous administration of colchicine.

4. Colchicine alone failed to incite egg release both in vitro and in vivo.

5. The left ovary was found to be larger than the right ovary and to extrude more eggs. There was a close correlation between ratio of weights for left and right ovaries and the ratio of number of eggs extruded by the left and right ovaries.

6. Eggs from colchicine-injected frogs failed to divide when fertilized with normal sperm.