Biological and Chemical Studies of Extracts of the Anterior Lobe Pituitary

THE relation of the anterior pituitary to the metamorphosis of Amphibia has provided a means of securing more intimate knowledge of the endocrine activity of this portion of the pituitary gland. The effects of extirpation and implantation of the gland upon the development of the larval forms indicated its relationship to metamorphic change, but the preparation and suitable administration of extracts of the anterior lobe capable of influencing these changes widened the field of investigation. As a consequence quantitative and qualitative information has been acquired, permitting the distinction of its activity from that displayed by the thyroid in metamorphosis, and its correlation to some extent with other known activities of the pituitary itself and those of other endocrine organs. Furthermore the standardisation of the method of preparation and the adoption of uniform conditions and procedure for the specific response—the production or acceleration of metamorphosis in the Amphibia—have made possible the biological assay of extracts (Spaul, 1930). The successful application of this method of assay is, however, limited considerably by the range—determined by the minimum dose influencing metamorphosis and the maximum response of the animal—and the degree of accuracy—dependent upon animal and other variations—that can be obtained. Hence, to further the study of the characteristics of this activity, a search is needed for some efficient reliable test and means of assay giving equivalent indication of biological activity and, at the same time, responsive beyond the limits imposed by biological assay, in which case the presence and amount of the activator failing to express itself biologically could be detected.