Distribution of acid and alkaline phosphatases in canine skin

Azo dye methods were used to determine the distribution of acid phosphatase (ACP) and alkaline phosphatase (ALP) in the skin of 25 Beagle dogs. ALP activity was found in dermal papillae of hair follicles regardless of their state of activity, in Huxley's layer of the inner root sheath of anagen stages, in myoepithelial cells of apocrine sweat glands, in germinative cells of sebaceous glands, in vascular endothelium, and in mast cells. The ACP activity was found in the epidermis, outer and inner root sheaths, keratogenous zone, hair cuticle and medulla, duct of sebaceous gland, and sebum. The results indicate that ACP and ALP are distinctive enzymes serving different biologic functions. The principal role of ALP in the skin appears to be dephosphorylation for adsorption and transport of chemical substances necessary for growth and maintainence of the pilary system and glandular adnexa. The ACP appears to be primarily involved in the breakdown of phospholipids and in necrobiosis of keratinocytes.