Studies on the Pituitary

Abstract

ABSTRACT The principal facts presented in this communication may be summarised as follows: Removal of the pituitary gland or of the anterior lobe alone results in involution of the ovaries, lowering of the serum calcium and cessation of skin secretion.Ovulation and skin secretion can be induced in Xenopus by injection of extracts of the pituitary gland. This communication has raised a number of issues which would have been investigated more extensively if circumstances had not forced two of the authors to leave South Africa. It is therefore advisable to bring into sharper relief the two most important conclusions which are justified by the facts recorded. The first of these is the very conclusive and complete evidence in support of the view that the anterior lobe of the pituitary controls the activity of the ovaries. Zondek and Ascheim (1927), Smith and Engle (1927), Bellerby (1930) and Parkes (1930) have shown that anterior lobe extracts or transplants stimulate the development of the ovaries in mammals. Unfortunately the removal of the pituitary gland in mammals is an operation of extreme difficulty. Conclusive evidence that the pituitary has a functional relation to the ovaries is lacking, unless the effects of operative removal can be brought into harmonious relationship with the effects of injection and implantation. In Xenopus it is possible to do this in a very striking manner. It is now therefore justifiable to assert that the results obtained by injection and implantation in mammals are not merely an indication of a new and specific pharmaco-dynamic constituent in the anterior lobe of the pituitary gland but of a genuine functional influence of the pituitary on the normal ovarian cycle. The new evidence presented in this communication reinforces a large volume of previous work on the comparative physiology of the ductless glands pointing to a widespread uniformity of endocrine phenomena within the vertebrate series. The other conclusion of outstanding importance which emerges from the present study is the influence of the pituitary gland on calcium metabolism. This opens up a field for further research and it would be premature to discuss it except in a very tentative way. Although there is no evidence at present to indicate that the pituitary gland exerts its influence on calcium metabolism directly, two considerations indicate that the influence of the anterior lobe on serum calcium is independent of the ovary. One is a comparison of the figures given for the eyeless and seeing groups in Table II which summarises the data presented in Sections II and III. The other is that Mirvish and Bosman (1927) have shown that injection of ovarian extracts lowers the serum calcium of rabbits.