A stereological study of the tuberomammillary nucleus in the Wistar rat: Morphological and functional comparison among subgroups E1-E2-E3

In the present study, we have calculated the total neuronal number and volume of the tuberomammillary nucleus and of each of its subgroups E1, E2 and E3 in the Wistar rat. This estimation was done using stereological methods that can produce accurate quantifications. Neuronal number was estimated by applying the optical fractionator and the total volume of the nucleus by Cavalieri's method. Simultaneously, we quantified the argyrophilic nucleolar organizer regions (Ag-NORs) of the neurons from these subgroups. The number and area of the Ag-NORs stained with the silver nitrate technique, reflect the protein synthesis activity of these neurons. Our results show that the tuberomammillary nucleus has a unilateral total neuronal number of 2,460 neurons and a unilateral volume of 0.08756 mm3. We also find statistically significant differences on a morphological level among the different subgroups of the tuberomammillary nucleus. Hence, E2 has the largest number of neurons followed by E3 whereas E1 is the subgroup with the smallest neuronal density. There were no significant differences in the functional parameters: area of neuronal nucleus and mean area and number of Ag-NOR, among the groups.