Morphology of the turkey vagina with and without an egg mass in the uterus

Abstract

In this study we examined the gross anatomy of the uterus and vagina in turkeys in egg production. With no uterine egg mass, removal of the tunica serosa that enclosed the uterus revealed deep periodic in-folding of the muscularis transversely circumscribing the sac-like segment. When the connective tissue embracing the neutral buffered formalin fixed vagina was completely teased free, the exposed tubular segment was shaped as a counter-clockwise spiral or as a series of angular, random bends. The uterovaginal junction was flush with the uterine mucosa or projected slightly into the uterine lumen. With a uterine egg mass, the deep in-foldings of the uterus were abolished. The only alteration to the morphology of the vagina was that the uterovaginal junction appeared dilated and pressed into its juncture with the uterus. Whether an egg mass was present or not, uterovaginal junction folds that projected into the uterus possessed sperm storage tubules. An egg mass in the uterus compressed the uterovaginal junction folds, and its mucosa became contiguous with the uterine mucosa. Finally, from an evolutionary perspective, in the turkey and possibly other species possessing a nonintromittent phallus, vaginal pleomorphism may have been driven primarily by the need to accommodate the overall length of the vagina in a limited abdominal space and to a lesser extent on sexual selection.