Androgen receptor (AR) immunohistochemistry of 68-day hyena penis. (A) Low magnification overview showing preputial lamina, tunica, urethra (Ur), corporal body (CB), and glanular erectile body (dotted lines). (B) Higher magnification of left box. Almost all cells within the corporal body (CB) are AR-positive. The tunica (between the two opposing arrows) consists of a mixture of AR-positive and AR-negative cells. (C) Higher magnification of right box in (A). The glanular erectile body contains a high percentage of AR-positive cells. (D) The urethral epithelium is mostly AR-negative, but is surrounded by AR-positive mesenchymal cells.