The hypothalamo-hypophyseal system of Rana temporaria under osmotic stimulation with special reference to the hypothalamo-median eminence-distal lobe axis.

The secretory activity of the hypothalamo-hypophyseal system in the frog Rana temporaria under conditions of dehydration has been studied histologically using two parameters, the amount of stained neurosecretory material and the amount of neurosecretory material labelled by a radioactive precursor. The results are indicative of an increased secretory activity of the hypothalamo-neural lobe system as a result of water deprivation. In addition the involvement of the preoptic nucleus-median eminence axis in osmoregulation is confirmed. The pattern of distribution of autoradiographic silver grains over the median eminence together with data from literature support the idea that mesotocine is involved in the regulation of the activity of the adenohypophysis.