[Rat paleoamygdala morphogenesis in the early juvenile period]

To characterize the structural remodeling of paleoamygdala during the early juvenile period, the studies were performed in 40 male and female Wistar rats on 21, 24, 28 and 31 postnatal days. Serial frontal brain sections stained with Nissl's cresyl violet were used to study the cytoarchitectonics of paleoamygdala (dorsomedial--Med, posterior medial--Mep and posterior cortical nuclei--Cop), as well as the dynamics of the formation of these structures, by means of the registration of planimetry characteristics, counting the number of neurons and glial cells, calculation of glial and apoptotic indexes. The results obtained suggest the heterochronism of the morphogenesis and gender-dependent differences in the differentiation of paleoamygdala structures. By day 21 (the beginning of early juvenile period), only Med appeared to be differentiated, while Mep became recognizable by day 24, and Cop acquired the characteristic cytoarchitectonics only by day 31 (the beginning of late juvenile period). Significant gender-associated structural differences were found in Med since day 28, and in Cop and Mep--on day 31.