1. ¹Department of Sex Hormones and Biology, Prince Henry's Institute of Medical Research, Monash Medical Centre, Clayton, VIC, Australia
2. ²Department of Biochemistry, Monash University, Clayton, VIC, Australia

Correspondence: Dr RA Hill, Prince Henry's Institute of Medical Research, Level 4, Block E, Monash Medical Centre, Clayton, VIC 3168, Australia. E-mail: Rachel.hill@princehenrys.org

Received 10 September 2007; Revised 11 December 2007; Accepted 14 December 2007; Published online 14 February 2008.

Abstract

The current study describes the presence of sexually dimorphic cell groups within the MPO of the 129SvEv, but not the C57BL/6J strain of mice. We detected galanin-positive clusters of cells located in the MPO of 129SvEv and C57BL/6J mice, with sex differences found only in the 129SvEv strain. Aromatase-positive and dense Nissl-counterstained clusters of cells were identified only in the MPO of 129SvEv mice, but not in the C57BL/6J strain. Furthermore, this study has demonstrated that the volume of these sexually dimorphic cell groups is regulated by estrogen, but not testosterone, as male aromatase knockout mice (which have high levels of testosterone, but no estrogen) show reduced cell group volumes. These structural changes, which occur in an estrogen-deficient state may influence male sexual behaviors.