Histomorphological Studies on the Different Nuclei of Hypothalamus of Indian Buffalo

Background: Hypothalamus is an integral part of the hypothalamo-hypophyseal ovarian axis. It contains several small nuclei that have been implicated in several specialized functions. It is the master endocrine gland because it regulates the activity of the pituitary. The present investigation was planned to elucidate the histomorphological details of different nuclei in the hypothalamus of Indian buffaloes. Methods: The hypothalami of buffaloes (n =52) were collected from local abattoirs and Teaching Veterinary Clinical Complex, GADVASU, Ludhiana. The tissue samples were collected from three levels i.e. the supraoptic, tuberal and the mamillary region of the hypothalamus and processed for paraffin sectioning and the sections were stained with various stains for histomorphological studies. Result: The well-defined cell groups or nuclei were identified both in the coronal and sagittal sections of the hypothalamus in all the reproductive phases. Eight nuclei were distinctly recognized in buffalo hypothalamus at three levels in the coronal sections of the hypothalamus. At the level of optic chiasma, the nuclei were paraventricular nucleus (PVN), supraoptic nucleus (SON) and preopticnucleus (PON); at the tuberal region, there were arcuate nucleus (AN) and ventromedial nucleus (VMN) and at the mammillary region, the lateral mammillary nucleus (LMN), medial mammillary nucleus (MMN) and posterior hypothalamic nucleus (PHN) were identified. Most of the nuclei consisted of a loose or compact heterogeneous collection of neurons. The neurons of the different nuclei were of variable shape. The cytoplasm contained a varied amount of Nissl material. The neurosecretory substance was peripheral in position. Small to large-sized blood vessels were observed in between the neuronal substance. The size of the neurons varied during different stages of reproduction.