Ultrastructural changes in neurons of the anterior subdivision of the rat hypothalamic ventromedial nucleus following repeated immobilization stress.

The fine structure of neuronal somata of the anterior subdivision of the hypothalamic ventromedial nucleus (VMN) was studied in repeatedly immobilized rats. After the 40th immobilization daily for 150 min a small population of neuronal somata containing endoplasmic reticulum formations classified as lamellar bodies and whorls were identified in the area investigated. These neuronal somata differed from the neighbouring perikarya of VMN also in several other ultrastructural features. They showed an extraordinarily dilated cisternae of the rough endoplasmic reticulum and of the Golgi complexes, moderately swollen mitochondria and a large number of free ribosomes evenly distributed in the cytoplasm.