Neurosecretory system of the toad Bufo arenarum hensel and its changes during inanition

Abstract

Studies have been carried out on the neurosecretory system of the toad Bufo arenarum Hensel in normal conditions and in different states of inanition. Extreme inanition produces an increase in neurosecretory material (NSM) which can be due to a decreased demand of the hypofunctioning adenohypophysis, or to a blockage of liberation of NSM. Furthermore, this accumulation of NSM in the hypothalamus could indicate that inanition does not stop its production. In normal conditions and especially in cases of extreme inanition the axons that form the hypothalamus-hypophysial tract show three different images of the NSM. This suggests the possibility that we are dealing with different secretory materials. At the same time the parallel increase of the NSM in the neuronal processes which go toward the third ventricle and of the Gomori-positive granules of the choroid plexus leads us to believe that other extrahypophysial pathways exist for the elimination of the NSM. A description is given, both in the controls and in the experimentals, of a group of neurosecretory axons which leave from the tract and run ventrally toward the optic chiasma.