Distribution of Merkel cells in normal skin and mucosae in dogs

Abstract

Merkel cells (MCs) are widely distributed in human skin, localized in a high proportion in the epidermis of hairy and glabrous skin in sites of high tactile sensitivity. In other mammals, snouts, touch domes, sinus hair follicles, lips and hard palate are rich areas of MCs. The aim of this study was to determine the normal distribution of MCs in the dog. Tissue samples from several locations were obtained from six adult dogs of different age, sex and breed, fixed in 10% buffered formalin, embedded in paraffin wax and cut into 3 mum tissue sections. The ABC method was used with different poly- and monoclonal antibodies tested (anti-Ck20, anti-Cks 8 and 18, anti-CgA, anti-NSE, anti-synaptophysin, anti-NF). MCs were observed in several sites of the skin and the oral, genital and nasal mucosae, as well as in different types of hair follicles. Face skin, digital pads, oral mucosae and vibrissae appear as high-density areas of MCs in dogs, in which they are frequently disposed in groups of three to ten cells. In many locations, the cells showed close relation with terminal axons. These locations are in accordance with studies in other mammals reported in the literature.