Species Specificity of the Gonadotropic Factors in Vertebrates

Abstract

M O OST recent studies concerned with the pituitary secretions have revealed increasingly frequent reference to the factor of species variation in the elucidation of certain of the data. In i9Z9 Houssay found that pituitary implants from different vertebrate classes could not duplicate the phenomenon of ovulation induction as it was produced in the toad by homoplastic implants. He was probably the first to advance the hypothesis of gonadotropic hormone species specificity as a basis for the interpretation of these results. Since that time it has become definitely established that there is a variation in qlaantity of the anterior pituitary hormones from species to species. This fact has been sufficient to explain many cases of apparent irregularities in response, or in dosage required to produce a given response. In some cases, however, and especially those cases in which the hormone donor and recipient are of widely divergent taxonomic types, it becomes clear that a qualitative variation in the hormones, like that postulated by Houssay, must be given consideration. Such a conception represents an advance over the general opinion held by endocrinologists a few years ago as summarized by P. E. Smith (I932) A species specificity either in a hormone or in the receptivity to a hormone is contrary to the current concept of hormonal physiology. Since i9Z9 numerous instances of refractoriness of animals to pituitary hormones of extra-specific origin have been presented in the literature of endocrinology, and these have been explained in various ways. The possibility of hormone species specificity has often been proposed, but almost never systematically tested. In I935 Creaser and Gorbman (I935, I936) examined the refractoriness of the common leopard frog, Rana pipiens, to large doses of mammalian gonadotropic materials, in contrast to its ready response to homoplastic treatment or treatment with pituitaries from closely related species. They concluded after elimination of all factors, excepting those characteristic and common to the number of actual hormone mixtures tested, that a gonadotropic hormone species specificity has been demonstrated. The discovery of antihormones by Collip and Anderson (I934) directed considerable attention to the question of pituitary hormone species specificity inasmuch as a number of investigators have claimed that antihormones are merely antibodies formed in response to immunologically distinct, and therefore species specific, hormones. The implication of hormone specificity in cases of chronic injection of anterior