FUNCTIONAL SEXUAL DIMORPHISM OF THE NUCLEOLAR ORGANIZER REGIONS IN THE TUBEROMAMILLARY NUCLEUS

The tuberomamillary nucleus (TM) is a cluster of magnocellular neurons that are located close to the mamillary recess or basal surface of th e mamillary body (MBs) and is the only known source of histamine (HA). The nucleolar organizer regions (NORs) of the nervous cells of the su bnuclei E1, E2 and E3 of the TM are quantified in this paper to discer n the existence of possible sexual differences in the overall neuronal protein synthesis between male and female rats in two phases of the o estrous cycle (oestrous-dioestrous). We have used the argentic impregn ation technique of the NORs (AgNORs) in both bilateral nuclei of the T M and found functional bilateral symmetry in its AgNORs. Furthermore, we demonstrate the existence of significant differences (P < 0.001) be tween sexes and between two phases of the oestrous cycle studied (oest rous-dioestrous) in the parameter of number of AgNORs per neuron. Horm onal manipulation of the TM in the rat during the two periods, postnat al or adult, shows the importance of the activational effect of the ho rmones on the activity of cellular protein synthesis.