Aspects of the skin morphology in the sub-Antarctic fur seal Arctocephalus tropicalis

DATA AVAILABILITY : The original database no longer exists. The photomicrographs on which the histological descriptions and parameter definitions are based will be available upon request.SUPPLEMENTARY FILE 1—ESM 1a. Photomicrograph (no scale available) of a cross section through the furred skin of a sub-Antarctic fur seal showing the two principal layers: (a) the outer epidermis, (b) the underlying dermis, (c) a common pilary canal, (d) a guard hair, and (e) associated under hairs. The glandular nature of the dermis is evident, although the poor resolution and low magnification complicates the clear separation of (f) sebaceous glands (usually adjacent to pilosebaceous units) and (g) sweat glands (usually around base of pilosebaceous units). ESM 1b Photomicrograph (no scale available) of a cross section through the naked skin of a sub-Antarctic fur seal showing the coiled, tubular nature of the secretory portion of a sweat gland. ESM 1c Photomicrograph (no scale available) of a cross section through the dermis of the furred skin of a sub-Antarctic fur seal, parallel to the surface of the skin, showing (a) guard hairs and (b) associated under hairs. In the one instance (c) both the guard hair and the associated under hairs are situated in the common pilary canal close to opening up at the surface of the skin. (DOCX 5680 KB)SUPPLEMENTARY FILE 2—ESM 2 Table 1. Common pilary canal density of sweat glands in the furred and naked skin of adult male sub-Antarctic fur seals. ESM 2 Table 2 Volume of the secretory section of sweat glands in the furred and naked skin of adult male sub-Antarctic fur seals (DOCX 30 KB)The present study examined whether sweat glands are present in the skin of sub-Antarctic fur seals, Arctocephalus tropicalis, using standard histological procedures and light microscopy. Aspects of the microanatomy and histology of skin were described to elucidate structure and function. Sweat glands were present both in the furred areas of the body trunk, as well as in naked skin areas of the flippers. The density of the apocrine sweat glands appeared higher in fur-covered areas than in naked areas, while the size of sweat glands was similar amongst naked and fur-covered skin. The superficial position of sweat glands in the dermis of naked skin areas and the large, coiled, tubular nature of the secretory portion seem to indicate sweat gland activity in contrast to the deep lying, narrow sweat glands in fur-covered areas.Open access funding provided by University of Pretoria.https://link.springer.com/journal/435hj2023Mammal Research InstituteZoology and Entomolog