title: Sex steroid hormones and sexual dimorphism of chemosensory structures in a terrestrial salamander (Plethodon shermani).
abstract: The volume of the vomeronasal organ (VNO) in the terrestrial salamander Plethodon shermani was approximately 1.7 times larger in adult males compared to adult females, even though male body size was, on average, slightly smaller than female body size. VNO cell density, however, was the same in adult males and females. The sex difference in VNO volume was found in sexually immature animals as well, indicating that the increase of plasma androgens that occurs at sexual maturity does not produce the sex difference in VNO volume. There was no difference in VNO volume between reproductive and non reproductive adult females, despite differences in plasma estradiol (E2) levels. The volumes of the main olfactory epithelium and muscles regulating diameter of the external nares were similar between males and females, indicating that the VNO per se, and not other aspects of the nasal cavity, was sexually dimorphic. To conclude, the sex difference in VNO volume appears to be a permanent sex difference that develops before sexual maturity. Future studies will examine the functional consequences of this structural sexual dimorphism in a peripheral sensory organ, the VNO.
authors.affiliation: Department of Biological Sciences, Duquesne University, 600 Forbes Ave., Pittsburgh, PA 15282, USA. woodleys@duq.edu
authors.forename: Sarah K
authors.initials: SK
authors.lastname: Woodley
mesh_terms: D000818:Animals; D004958:Estradiol / Q000097:blood; D005260:Female; D012739:Gonadal Steroid Hormones / Q000097:blood*; D008297:Male; D018482:Muscle, Skeletal / Q000033:anatomy & histology; D009666:Nose / Q000033:anatomy & histology*; D009831:Olfactory Mucosa / Q000033:anatomy & histology; D012727:Sex Characteristics; D013739:Testosterone / Q000097:blood; D014562:Caudata / Q000033:anatomy & histology* / Q000097:blood*; D019147:Vomeronasal Organ / Q000033:anatomy & histology
chemical_list: D012739:Gonadal Steroid Hormones; D013739:Testosterone; D004958:Estradiol