Representative micrographs show morphology of epididymides of control (A-C) and flutamide-treated boars (D-O). Hematoxylin and eosin staining. Scale bars represent 20 μm. Caput epididymis. In the control group (A) and flutamide-treated groups (D, G, J, M) the epithelium composed of principal cells (bold arrows) and basal cells (arrows) is observed. Outside the stroma layer is seen (open arrowheads). Irrespective of the groups, principal cells (bold arrow in inserts in A, D, G), few basal cells (arrow in inserts in A, D) or no basal cells (dashed-line ovals in insert in G) and stromal cells (open arrowhead in inserts in A, D, G) are seen in the initial segment of the epididymis. In PD2 and PD90 groups an agglomeration of phagocytic leukocytes in the lumen (asterisks) and sperm embedded in intraluminal cell debris are observed (J, M, at higher magnification, insert in J). Leukocytes in the stroma are also seen (insert in M). Corpus epididymis. The composition of the cells in the epithelium and in the stroma layer is similar to that of the caput. Note a reduction of the epithelial heights (brackets) in males after flutamide treatment (E, H, K, N) compared to the control (B). Scarce spermatic content are seen in PD2 and PD90 groups (K, N) compared to the respective controls (J, M). Cauda epididymis. Note increased height of the epithelium and enlarged stroma layer after flutamide treatment (F, I, L, O) compared to the control (C). In GD20 and GD80 groups less folded wall of the epididymal duct is seen (F, I) whereas in PD2 and PD90 males deep invagination of the epithelium (L) or even its closure is observed (insert in O). In lumina cell sloughing is seen (arrowheads) (I, insert in I) or bubble-like vesicles of sloughed cytoplasmic membranes are visible (arrowheads) (L, O). After flutamide exposure at GD20 the intra-epithelial lymphocytes are seen (arrowheads) (insert in F). Scarce spermatic content are seen in GD20, PD2 and PD90 groups (F, L, O) compared to the respective controls (D, J, M).