Meeting Abstract

32.2  Monday, Jan. 5  Sexual Dimorphism and Seasonal Variation in the Harderian Gland of the Red-sided Garter Snake MASON, R.T.*; ERICKSON, S. M.; HALPERN, M.; Oregon State University; Oregon State University; SUNY Downstate Medical Center, Brooklyn masonr@science.oregonstate.edu

The Harderian gland of the red-sided garter snake, Thamnophis sirtalis parietalis, is a secretory structure that plays a role in the vomeronasal system by solubilizing semiochemicals, such as the otherwise insoluble female garter snake sexual attractiveness pheromone. Detection of the pheromone by the vomeronasal system is essential for male courtship of female garter snakes. Feeding, which occurs only in the summer, involves detection of prey chemicals by the vomeronasal system as well, and may require carrier molecules (binding proteins) to deliver prey proteins to the vomeronasal organ. Because only male snakes respond to the female pheromone and breeding occurs primarily in the spring and feeding in the summer, the morphology of the Harderian gland was expected to be sexually dimorphic and seasonally variable. We found this to be true. Harderian glands were larger, cell heights were greater, and lumen diameters larger in the summer than in the winter or spring. Whereas the acinar cell heights and lumen diameters of males increased significantly from winter to spring, those of females did not. Sexual dimorphism was most evident in the acinar cell heights and lumen diameters in the spring, with males having significantly greater cell heights and lumen diameters than females.