Periodically a graafian follicle ripens and ruptures, and the ovum escapes. The ruptured follicle then develops into a corpus luteum, a gland of internal secretion which is necessary for the implantation of the fertilized ovum. These brief facts barely outline the immensely complicated story of ovulation. No one has actually seen a graafian follicle rupture nor has any one heretofore succeeded in producing ovulation in women. Theoretically, the ideal substances for this purpose would be certain extracts of the anterior lobe of the pituitary gland, but these have not been available in a sufficient state of purity. Gonadotropic substances derived from the urine and blood of pregnancy have failed to produce any consistent changes in ovarian activity when given parenterally. Recently a gonadotropic substance has been found in the serum of pregnant mares and sufficiently purified, it is thought, to bring about ovulation in women. This substance was first observedTHE EXPERIMENTAL PRODUCTION OF OVULATION. JAMA. 1938;111(15):1380. doi:10.1001/jama.1938.02790410036014Customize your JAMA Network experience by selecting one or more topics from the list below. Create a personal account or sign in to: