The Efferent Ductules in the Lizard Eutropis carinata: a Functional Morphology and Ultrastructural Study

Abstract. Efferent ductules are part of the male reproductive system. They play a role in providing a nutrient environment for the maintenance of the spermatozoa. Efferent ductules are studied exhaustively in birds and mammals, but reptiles, the first vertebrates that successfully adapted to life on land, have received little attention among the comparative biologists. Hence, the present study aimed to study the seasonal variation in an extra-testicular portion, the efferent ductules, in the male reproductive system of the lizard Eutropis carinata. The results revealed that the epithelium of these ductules is lined by cuboidal non-ciliated cells and ciliated cells. Ultrastructural features of the non-ciliated cells revealed the role of endocytosis and secretion. During the breeding season, the epithelium is positive to periodic Schiff and bromophenol blue staining, indicating the presence of carbohydrate and protein. Histological and histometric parameters exhibit significant seasonal differences. However, there is not much seasonal ultrastructural variation, except for reduced cell height and less cytoplasm as well as reduced granular material in the lumen. Based on the above results, the present study for the first time reveals that the efferent ductules form an essential link between the testis and the epididymis and serve as a conduit for sperm, absorption of rete testis fluid, and secretion. Further, although there is no seasonal variation in the type of cells throughout the length of the efferent ductules during the breeding and non-breeding seasons in E. carinata, the morphology, ultrastructural modifications, activity, and function vary during these seasons.