Zones of sexual dimorphism in the cortico-medial group of nuclei of the amygdaloid complex.

Abstract

With the aim to reveal sex demorphic zones by means of caryometry, 22 zones of the cortico-medial group of the amygdaloid complex (AC) nuclei have been investigated in rats (15 males and 10 females). Per each zone investigated 200 cellular nuclei are measured. Parameters characterizing distribution of the neuronal nuclei volumes in the zones studied are calculated, influence of the sex factor on the nuclear size are revealed by means of variance analysis. Basing on the results of the investigation, a complete idea on topography of the sex demorphic zones in the territory of the cortico-medial group of the AC nuclei is given. These zones are predominantly localized in the anterior and posterior parts of the AC, situating mainly in the rostral and caudal areas of the medial and cortical nuclei. The results demonstrate existence of the rostro-caudal gradient in the structural-functional organization of the cortico-medial group of the AC nuclei and prove that before suggested division of the AC into anterior, central and posterior parts is correct. It is possible to suppose that the cause of accumulated and still accumulating in the literature contradictions on functional differentiation of the AC is lack of registration of sex differences and of the rostro-caudal gradient in organization of this cerebral formation.