THE STRUCTURAL TRANSFORMATION OF PALEOAMYGDALA DURING THE POSTNATAL ONTOGENESIS IN RATS

Objective - to perform a comparative analysis of the characteristics of microstructures of phylogenetically diverse rat amygdala formations at various time points of the early juvenile period. Material and methods. The work was performed on 40 Wistar rats. The brain was examined on 21-, 24-, 28- and 31 day of the postnatal period (for each time point, material was obtained from 5 males and 5 females). The specific surface areas of paleoamygdala and basolateral amygdaloid nucleus were calculated on the paraffin frontal sections (20 μm thick) stained with cresyl violet according to the Nissl method. Comparison of the quantita tive data for various age groups was carried out by φ method or using the parametric statistical approaches. Results. In rats, no changes in the specific surface area of rat basolateral amygdaloid nucleus (a phylogenetically new structure) and amygdala were observed from 21 to 28 days of the postnatal period. However, it was increased by the end of the early juvenile period, between Days 28 and 31 of postnatal ontogenesis. The paleoamygdala specific surface area remained unchanged during the early juvenile period. Conclusions. The increase in the rat amygdala size during the postnatal ontogenesis is due to the progressive development of its phylogenetically young structures that have strong connections with the neocortex.

corpus amygdaloideum, paleoamygdala, lateral amygdaloid nucleus, postnatal ontogenesis