Cytological Changes in Frog Pituitary Considered in Reference to Sexual Periodicity

Recent experiments with Amphibia indicate that the anterior lobe of the pituitary exerts a controlling influence not only on the development of the primary sex organs, but also on the release and discharge of the sex products. Wolf 1 and Rugh, 2 working with various Anura, have demonstrated that amplexus and shedding of the sex products can be induced in mid-winter by simple hetero- or homoplastic implantation of anterior lobe tissue. Houssay and Lascano-Gonzales 3 observed a degeneration of the testes following hypophysectomy in the toad. The writer wishes to present briefly the results of a cytological study of the frog anterior lobe, and on the basis of cytological evidence to postulate the rôle played by the pituitary in the mechanism of sexual periodicity.

Several species of the genus Rana were used in this study. At regular intervals throughout this annual cycle specimens were killed and the cytological condition of the anterior lobe pituitary was noted. Various sublimate and osmic acid fixatives were used in preparing the tissue for microscopic examination. Staining procedure most consistently used was a modification of the acid fuchsin-methyl green technique.

The general pattern of the winter frog anterior lobe is similar to that found in the other vertebrates. The numerical proportion, the inclusions and the structure of the cell types, however, do not conform entirely to those of the higher vertebrates, particularly mammals. The basophiles are small cells, few in number, and their general appearance does not suggest high secretory activity. True acidophiles, on the other hand, are larger and are filled with densely packed acidophilic granules. True chromophobes are as large as the acidophiles, but are more or less free of specific granulation. Grading between the true acidophilic type and the true chromophobic type are found cells exhibiting intermediate stages of acidophilic granulation, some containing comparatively few acidophilic granules, while others approach the true acidophiles in amount of granulation present.