Distribution of Jab1/CSN5 in different regions of the rat epididymis during postnatal development. Jab1/CSN5 immunopositivity is detected in the CT, CS and CA at days 5 (A, B, C), 15 (D, E, F), 30 (G, H, I) and 60 (J, K, L). Jab1/CSN5 is found in the cytoplasm of epithelial cells (EC) of the epididymis at day 5 (A, B, C). Both the basal (BS) and principal (PC) cells of the CT, CS and CA epididymis are found to be immunopositive for Jab1/CSN5 at days 15, 30 and 60 (D-L). In addition to the nuclear region of epithelial cells (EC), Jab1/CSN5 is highly expressed in the cytoplasm in the CT and CS epididymis at days 30 (G-I) and 60 (J-L). Spermatozoa (Sp) are weakly immunopositive for Jab1/CSN5 at day 60 (J-L). No significant staining is observed in the negative controls (at the upper corner of panels A-L). CT: caput, CS: corpus, CA: cauda. Scale bars: 25 μm (A-C); scale bars: 50 μm (D-L).