Parabiotic Experiments on the Development of Neurohypophysis (With Bufo vulgaris formosus)

Abstract

The Rathke's pouch was excised from larvae of Bufo vulgaris formosus in the later stage of the neurula, and one group were brought to parabiosis with intact larvae, and the other cultured as single larvae, and differentiation in these two groups were compared.
1) In single larvae, from which the Rathke's pouch was removed, the ventral wall of the infundibulum showed only slight thickening. But nevertheless it was clearly distinguishable from the other part of the infundibulum, and histologically its structure was identical with that of the neurohypophysis. The thyroid in these larvae was atrophied, and their skin color was paler than that of controls. Metamorphosis was inhibited in them.
2) The differentiation of the ventral wall of the infundibuliim in parabiotic adenohypophysectomized larvae advanced to higher degree as compared with that in the single operated larvae, but its cepholocaudal diameter ranged only 1/2-1/4 that of the normal neurohypophysis. The quantitatively higher growth in the parabiotic larvae is considered to indicate the effect of humoral induction by the neurohypophysis of the host. The thyroid in the parabiotic operated larvae showed neither atrophic nor degenerative picture. Macroscopically, no difference in skin picture was obsesved between the host and parabiotic partner, and the latter continuted growth with the former until the attainment of the metamorphosis.