A scanning electron microscope study of the tunica vaginalis testis in the mouse.

On the visceral layer of the mouse tunica vaginalis testis are two populations of mesothelial cells: one carrying numerous surface microvillia and the other with fewer microvilli thus presenting almost bare areas. Intercellular stomata and smaller gaps are seen only between the cells of the bare areas. Underlying the stomata the surface of a second cell, which probably represents the endothelial lining of submesothelial lymph vessels, is often seen. Mesothelial cells of the parietal layer lack microvilli, stomata and gaps but show numerous long filamentous processes on the apical cell surface and at the lateral cell borders where they connect neighbouring cells as they overlie unusually wide intercellular clefts.