Ultrastructural Analysis of the vascular zones of the Dromedary Neurohypophysis

Abstract

The structural elements of the vascular zones are endothelial cells, basal lamina, pericytes and neuroglial processes that can undergo structural remodelling according to hormonal demand. The qualitative and the quantitative ultrastructural characteristics and seasonal variations of these elements in the neurohypophysis of the dromedary were investigated. The results showed a complex basal lamina, abundant fibrillary elements at pericytes and an important membrane exchange in endothelial cells. Quantitative analysis of neurovascular contacts did not show between seasons, a significant variation in the number of nerve terminals contacting basal lamina, however the mean number of glial processes significantly increased in winter (p = 0.037). We think that, as the animal is facing situations of combined stresses in summer, high temperature, insolation…, that lead to increase water demand, these would exert ultra-structural effect on the liberation of neuropeptides at perivascular to decrease water output.