THE DENTATE GYRUS IS SEXUALLY DIMORPHIC IN PREPUBESCENT RATS - TESTOSTERONE PLAYS A SIGNIFICANT ROLE

In a morphological examination of the hippocampal formation of pre-pub escent rats, a testosterone-related sexual dimorphism was observed. Th e dentate gyrus granule cell layer was greater (8-9%) in width and len gth and laterally asymmetrical in males and in testosterone-treated fe males. This dimorphism was previously observed in adult rats. These da ta demonstrate that the dimorphism exists prior to puberty and is ther efore not dependent on hormone changes associated with this event. In addition, a correlation between the size of this cell layer and perfor mance on a spatial task were observed.