α-Klotho protein expression and distribution in human epithelial and reproductive tissues. IHC, positive staining (brown) was found in all the cellular layers of the epidermis (A) and appendage tissue such as hair follicle and sebaceous gland (B). Intestinal expression was primarily found in epithelial cells as illustrated in jejunum (C) and colon (D). In reproductive tissues, positive staining was found in epithelial Sertoli cells (E), testosterone producing Leydig cells (illustrated with white arrows) of the testis (F), and epithelial cells of the prostate gland G). H–K, In mammary tissue (H), endometrium of uterus (I), and endometrium of salpinx (K), the epithelial cell layer was staining strongly for α-Klotho protein; insets are larger magnifications of the epithelial layer. n ≥ 5 for each tissue.