RESUMO
Observations of the ultrastructural changes in neurons of hypothalamie arcuate, supraoptic and paraventricular nuclei were carried out in the rats following gossypol treatment at a dosage of 30mg/kg/day for 5 weeks. The results showed that after gossypol treatment no marked changes in supraoptic and paraventricular cells could be seen at electron microscopic level, and that there appeared a series of ultrastrucrural changes reflecting increased neurosecretory activity in some of arcuate neurons.They were as follows: Golgi complex and rough endoplasmic reticulum were slightlydilated and filled with homogeneous, low electron density materials in their cisternae; the amounts of neurosecretory granules, lysosomes, nucleolus-like bodies, and microtubules were increased. The nature, significance and cause of these changes are discussed.