Epididymal cauda in active period. (a) Epididymal section observed at low magnification by scanning electron microscopy showing a low height of the epithelium (Ep), and a dilated lumen (L) with abundant sperm (sp). SEM: ×150. (b) In this image at higher magnification shows the organization of the stereocilia (s) forming sperm (sp) reservoirs. SEM: ×7000. (c) Semithin cut obtained from the same region of the epididymal cauda. A high number of sperm (sp) are stored in the epididymal lumen (L). Cl: clear cell; P: principal cells; n: nuclei; Lp: lamina propria; s: stereocilia. TB: ×1000.