Egg-Laying in Triturus Viridescens Following Pituitary Transplants

Abstract

From the work of Smith, Smith and Engle, and Engle it is known that anterior pituitary transplants hasten sexual maturity in rats and mice. In females the ovaries contain an excessive number of mature follicles and superovulation occurs. Egg-laying, mating, and subsequent development of the fertilized eggs has also been induced in frogs, in autumn, by Wolf. Experiments were undertaken to see if females of urodeles (Triturus viridescens) would also deposit eggs out of season if they received transplants of the pituitary gland. In October, a student working with the writer, placed, on alternate days, whole glands in females unilaterally castrated. After 7 transplants one individual laid an egg (October 22nd). Transplants were continued and 15 more eggs were laid up to November 16th when the animal was killed. Six other females also shed eggs at other times after varying numbers of transplants. Early in December, 5 normal adult females received whole pituitary gland transplants from normal adult males (one transplant daily for 12 days). Five others (controls) were engrafted with small bits of muscle. All grafts were implanted either intramuscularly or intraperitoneally. Animals receiving pituitary glands laid eggs during (Numbers 1, 2, 4) or after (Numbers 3, 5) the grafting (Graph 1). Numbers 1, 2 and 3 laid 86, 45 and 32 eggs respectively over a number of days while Numbers 4 and 5 laid 8 and 7 respectively. The last 2 animals were small as compared with the first 3 and were selected purposely for comparing with the large specimens which from external examination very evidently contained sizable ovaries. None of the animals (Numbers 6-10) which received muscle laid any eggs. After the egg-laying in the pituitary-engrafted animals ceased, another series of transplantations was begun (January 7th) using the same animals.