SEX AND INTRAUTERINE POSITION INFLUENCE THE SIZE OF THE GERBIL HIPPOCAMPUS

Sex differences in home range size and spatial ability are predictive of sex differences in the relative size of the hippocampus in rodents. Such differences in behavior and hippocampal volume are presumed to b e, in part, the result of differences in perinatal exposure to hormone s. We predicted from differences in the size of home ranges of male an d female Mongolian gerbils (Meriones unguiculatus) in the wild that th e hippocampus of male gerbils would be relatively larger than that of females. We examined the effect of prenatal hormonal influences on hip pocampal size by comparing hippocampal volume of males and females fro m 2F and 2M intrauterine positions to that of randomly selected males and females. We found that, as predicted, randomly selected males had a significantly larger hippocampus, relative to telencephalon, than di d randomly selected females. However, males and females from 2F and 2M intrauterine positions did not differ in relative hippocampal size. P ossible explanations for the absence of a sex difference in hippocampa l size in male and female gerbils from 2F and 2M intrauterine position s are discussed. Copyright (C) 1996 Elsevier Science Inc.