Transverses section of cauda of epididymis of Wistar Rats aged 66 days (A) cauda in non-treated groups(G1) showed pseudostratified columnar epithelial that consist of principle cell(PC), basal cell (BC), lined tubules that full with sperms (S) and between tubules loose connective tissue (CO). HandE, 200X. (B) Cauda of epididymis of treated groups (G2) with 50µg/rat of estradiol benzoate showed most tubules lumen (LM) irregular in shape, shrinking, smaller and devoid of sperms or had debris (DS). There was hyperplasia (HP) with increased in thickness of epithelial and appeared cribriform forms (CR) and there is large amount of collagen fibers (CF) between tubules. Van Gieson’s stains 200X.