THE OVARIAN CYCLE IN THE VIVIPAROUS TELEOST XIPHOPHORUS HELLERI

Abstract

Mature ovaries were arranged in serial order and used as a basis for the study of changes in follicles, ova, and embryos. Pregnancies could be dated approximately from either dissected or sectioned ovaries, but not externally in the living animal. The ovum increases in organic content during the first J of the cycle, then it is fertilized. The latter 2/3, during which the embryo develops within the follicle, show no increase in organic content of the ovum although ash, water, and total weight increase with the growth of the embryo. After parturition the emptied follicle, which during the period of embryonic growth showed no activity, hypertrophies, then secretes and sloughs its contents into the ovarian cavity.