Magnocellular neurosecretory centers in the rat hypothalamus

Abstract

Hypothalami from normal rats were examined after preparation with Gomori's chromalum‐hematoxylin stain for neurosecretory material. In addition to the supraoptic and paraventricular nucleii, five additional nuclear masses of neurosecretory cells were found. These all formed more or less compact cellular groups, clearly demarcated from surrounding neural tissue and with constant location from animal to animal. One nucleus, immediately posterior to the anterior commissure, along the ventricular wall, is termed anterior commissural. Two others, being dorso‐lateral to the columns of the fornix, are termed anterior and posterior fornical. Midway between the paraventricular nucleus and the optic tract, a characteristically shaped nucleus of very compact cells, the nucleus circularis, is encountered. Finally, another group of cells is seen dorsal to the optic tract in the middle of the medial forebrain bundle, the nucleus of the medial forebrain bundle.