Ovulatory Response of Rana pipiens to Mammalian Gonadotropic Factors and Sex Hormones

Abstract

The complete refractoriness of the common frog, Rana pipiens, to mammalian gonadotropic factors has attracted considerable attention, especially from point of view of comparative endocrinology and when considering such concepts as species gonadotropic specificity. 1 On the other hand, stimulation of the reproductive tracts of immature mice has been brought about by large doses of fresh anterior pituitary from Rana pipiens. 2 For further investigation of this problem the following preliminary experiment was undertaken.

Twenty-nine adult female Rana pipiens received abdominal injections, in varying concentrations, of (1) gonadotropic factors of mammalian anterior pituitary, (2) gonadotropic factors of pregnant mare's serum (gonadogen), (3) α-estradiol dipropionate (diovocylin), (4) progesterone (lutocylin), and (5) testosterone propionate (oreton). Injections of distilled water, sesame oil, and homoplastic pituitaries served as controls.

Approximately 72 hours after treatment an attempt to strip eggs was performed, immediately followed by laparotomy. Portions of oviducts and ovaries were preserved for histological study while the pituitaries were prepared for cytological study. The ovulatory response was recorded as the relative number of eggs in the oviducts. In cases of negative response to stripping, a pituitary from a normal female frog was injected, which in all cases resulted in complete ovulatory response thus demonstrating that these specimens were capable of responding.

The substances injected, dosage and ovulatory response are recorded in Table I. This shows that 4 frogs treated with varying doses of mammalian anterior pituitary gonadotropic factors, were completely refractory. Also 5 frogs receiving varying doses of gonadotropic factors of pregnant mares serum, were completely refractory. Likewise, 5 frogs treated with varying doses of α-estradiol dipropionate, gave no response. However, all 5 frogs injected with varying doses of progesterone gave positive ovulatory responses, ranging from 5 to 50%. Of 10 frogs treated with varying doses of testosterone propionate, 8 gave positive responses ranging from 5 to 100%, while 2 failed to respond. The controls of distilled water and sesame oil were completely negative, while the pituitary controls were completely positive.