Figure 5. Immunohistochemical staining of CREM in the testis. The Roman numerals indicate the identifiable stages of the tubules. (A) Sham control rat. CREM staining was present primarily in young spermatids and maturing pachytene spermatocytes in stage XII epithelia; its presence in spermatogonia and prepachytene spermatocytes was rare. (B) An untreated SCI rat showing the presence of CREM immunostaining in young spermatids in most of the tubules. Note the difference in the intensity of CREM staining between 3 adjacent stage VII tubules. (C) An SCI rat that received 3-cm TC implants. Note the absence of CREM immunostaining in young spermatids that was present in spermatogonia and early spermatocytes. (D) Enlargement of portions of 2 tubules taken from (C) showing the presence of CREM immunostaining in preleptotene spermatocytes (arrowheads) in a stage VIII tubule and leptotene spermatocytes (L) and A2 spermatogonia (A2) in an adjacent stage XI tubule. Note the absence of CREM staining in young spermatids. (E) An SCI rat that received 5-cm TC implants. Note that CREM immunostaining also was not present in young spermatids despite the presence of complete spermatogenesis in stage VII and VIII epithelia. (F) Enlargement of 2 adjacent tubules from area shown in (E), showing the presence of CREM in zygotene spermatocytes (Z) of a stage XII tubule and in young pachytene spermatocytes (P) in an adjacent tubule. Note that none of the young spermatids were stained. (G) An SCI rat that was given 10-cm TC implants showing the presence of CREM immunostaining in young spermatids as in those seen in a sham control rat in panel A. (H) A sham control rat given 3-cm TC implants for 8 weeks. Cellular distribution of CREM immunostaining in young spermatid was comparable to that of the sham control rat shown in panel A. This section has not been counterstained with fast green. (I) Negative control stained with antigen-adsorbed anti-CREM antibody.