Epididymis of the Lizard Eutropis carinata: A Light Microscopic and Ultrastructural Seasonal Study

Abstract

The epididymis of the lizard Eutropis carinata can be divided into four regions viz., an initial segment (extra testicular) Efferent ductules (Eds) and three regions, the anterior region, a broad middle, and a narrow posterior, comparable to the caput, corpus, and cauda epididymidis of mammals. The anterior region of the epididymis is closely associated with a whitish initial segment (extra testicular), the Efferent ductules (Eds). The epididymal wall consists of an epithelial layer lining the lumen resting on a basement membrane surrounded by four to five layers of smooth circular muscles, a layer of connective tissue, and a layer of serosa. The ultrastructure study of the initial segment of epididymis the Eds during breeding season discloses four cell types in its epithelium viz., ciliated, non-ciliated, Apical-Mitochondria Rich Cells (AMRC), and basal cells. The anterior, middle, and posterior regions of the epididymis show five different cell types namely principal, basal, AMRC, narrow, and clear cells. Ciliated and non-ciliated cells are limited to the initial segment of the epididymis while, principal, narrow, and clear cells are found in the rest of the three regions of the epididymis. Basal and AMRC are found in all four regions. AMRCs are the most abundant cell type in the initial segment while principal cells are the major components of the epithelial lining of the remaining regions of the epididymis. During the non-breeding season, all the cell types are present but with regression and altered cytology of the cells without any sign of cellular activity in the different regions of the epididymis. During the breeding season, even the circulating testosterone levels are significantly higher compared to the non-breeding season. This is the first report describing different cell types in the initial segment and three different regions of the epididymis with ultrastructural seasonal variations in the Keeled Indian Mabuya, Eutropis carinata (Scincidae).