Hypothalamic neurosecretion in relation to water deprivation in ploceids of arid and swampy zones

Abstract

The effects of 72 hours of dehydration on the hypothalamo-neuro-hypophyseal system have been compared in three avian species which originate from different climatic habitats but belong to the same genus, Lonchura. In L. malacca, which is an inhabitant of swampy, non-arid regions, the neurosecretory nuclei are activated and there is a depletion of neurosecretory material from the nuclear regions and neurosecretory tract, as well as from the neurohypophysis. In L. punctulata, an inhabitant of woods and grasslands, the supraoptic cells show signs of activation. To some extent, a depletion of the neurosecretory material is observed from the neurohypophysis. In the fibrous layer the continuity of the neurosecretory material along the tract is not maintained to such an extent as in the control. In L. malabrica, which lives in semi-arid regions, there is some activation of the supraoptic nuclei but there is little to no depletion of the aldehyde fuchsin-positive material from the neurohypophysis and the tract leading to it. The results of this investigation are indicative of a correlation between the neurosecretory mechanism and ecologic adaptation.