Further Experiments on Induction of Ovulation in Toads. ∗

Abstract

The authors have been interested in the problem of specificity of the maturity hormone of the anterior lobe of the hypophysis. Previously we 1 have reported that heteroplastic hypophysis implants from frogs may be used to induce ovulation in toads, thus proving the non-specificity of the maturity hormone in anurans. Kuyper, Pfeiffer and Wills, 2 on the other hand, were unable to produce ovulation in toads using injections of hebin (prepared from pregnancy urine). In our present experiments, we wished to further test the specificity of the hormone by implanting into toads, hypophyses from 2 different vertebrate classes. Garpike and albino rats were used.

A series of 6 Bufo americanus females were given daily implants of 2 to 4 hypophyses from garpike (Lepidosteus platystomus Rafinsque and L. osseus L.). Ovulation occurred in 5 animals between the second and sixth day. The sixth female died of an infection without ovulating. The best results were obtained by implanting 4 hypophyses daily. The discharged eggs in some cases appeared to be overripe. In several cases all the eggs were not discharged at one time. In most cases the eggs were retained in the uteri longer than normally. Males placed with the females did not copulate and artificial fertilization was not attempted so the eggs did not develop.

One “jumbo” female frog (Rana pipiens) was given daily implants of 4 Lepidosteus hypophyses. Eggs were laid on the fourth day. Ovulation and eggs appeared normal.

Two toads were given daily implants of 2 and 4 hypophyses from albino rats for 5 and 8 days respectively. Ovulation did not occur. The animal which received 2 hypophyses daily, died at the end of the fifth day as a result of shock and hemorrhagic condition in the region of the implants.