FUNCTIONAL SEXUAL DIFFERENCES IN RAT MAMMILLARY BODIES - A QUANTITATIVE AG-NOR STUDY

The mammillary bodies of the posterior hypothalamus are one of the CNS structures in which structural sexual dimorphism has already been des cribed. This study quantifies the argyrophilic nucleolar organizer reg ions (NORs) of the neurons from this region in the male and female rat s, the latter during two major phases of the estrous cycle (estrus-die strus). The number and relative area of these NORs stained with a silv er nitrate technique are considered as an index of the global protein synthesis of the neurons in the different nuclei from the mammillary b odies. Our results show the existence of statistically significant dif ferences between sexes and estrous cycle phases. These findings sugges t a significant influence of gender and the hormonal state on the neur al activity of the MB.