Histo-architecture of Neurohypophysis with Special Reference to Herring Bodies in Madras Red Sheep

A study on the pituitary gland was carried out to record the histoarchitecture and occurrence of Herring bodies in 30 Madras red sheep. The tissues were processed for histological observations and were stained with standard histological and histochemical techniques. The neurohypophysis consisted of median eminence, infundibular stem, and infundibular process or pars nervosa in all the age groups. The median eminence was divided into zona interna and zona externa. Infundibular stem appeared as a narrow middle segment of the neurohypophysis which comprised of nerve fibres, pituicytes and blood vessels. The infundibular cavity was the extension of the third ventricle covered by the wall of the infundibular stalk and lined by a single layer of ependymal cells. The pars nervosa of neurohypophysis was an expanded terminal part comprised of the unmyelinated axons, blood vessels and pituicytes. The axons of the hypothalamo-hypophysial tract are atypical as they showed Herring bodies which appeared as small distinctly granulated vesicles to large globular bodies varied in size from 12 to 120 μm in median eminence and infundibular stem and increased in size upto 200 μm in pars nervosa.