EFFECT OF SITE OF INSEMINATION UPON THE FERTILITY OF GONADOTROPHIN-TREATED RABBITS OF DIFFERENT REPRODUCTIVE STAGES1

Abstract

THAT the fertilizability of artificially ovulated eggs is dependent in part upon the stage of the reproductive cycle in which ovulation is induced has been demonstrated in cattle (Casida et al., 1940, 1943), sheep (Murphree et al., 1944), rabbits (Boyarsky et al., 1947; Murphree et al., 1947; Austin, 1949) and swine (Tanabe et al., 1949). Induction of ovulation in females by use of gonadotrophic hormones when their ovaries contain functional corpora lutea has yielded few or no fertilized eggs with either natural mating or artificial insemination, whereas treatment in the follicular phase has resulted in good fertility. An association has been found between the age of the corpora lutea in the rabbit and the degree of suppression of fertility (Boyarsky et al., 1947; Austin, 1949). The corpus luteum hormone, progesterone, has been demonstrated as one endocrine entity concerned in the suppression of fertility in the experimentally ovulated ova (Boyarsky et al., 1947).