SEXUAL DIMORPHISM OF HIPPOCAMPUS MASS IN BANK VOLES (CLETHRIONOMYS GLAREOLUS, RODENTIA)

Sexual dimorphism of absolute and relative hippocampus mass was studied in bank voles (Clethrionomys glareolus) from two natural populations (West Siberian and Moscow regions). Overwintered males and females of the autumn generation captured in June were compared. When compared to other brain regions (bulbus olfactorius, neocortex, striatum, paleocortex, diencephalon, mesencephalon, cerebellum, mielencephalon), the hippocampus showed the most substantial sexual differences in its size. The absolute mass of the hippocampus in males was 6.2-9.1% higher than in females. The relative hippocampus mass (compared to the total brain mass) in males was 6.5-7.6% higher than in females. The differences were statistically significant in both populations. Sexual dimorphism of the hippocampus is discussed in relation to differences in bank vole male and female spatial behavior.