Lectin histochemistry of snout skin and foot pads in the wolf and the domesticated dog (Mammalia: Canidae).

The distribution and selectivity of complex carbohydrates in the snout skin and the foot pads of the wolf and the domesticated dog were studied by means of light-microscopic histochemical methods, particularly lectin histochemistry. In the snout, moderate to strong staining reactions were confined to intercellular substances among the epidermal cells, containing neutral glycoconjugates (glycoproteins, glycolipids) with various saccharide residues (alpha-D-mannose, beta-N-acetyl-D-glucosamine, alpha-N-acetyl-D-galactosamine, beta-D-galactose). In the foot pads, distinct reactions were found in neutral glycoconjugates of intercellular substances of the stratum corneum, with alpha-N-acetyl-D-galactosaminyl and beta-N-acetyl-D-glucosaminyl residues, but only in the wolf, whereas in the dog such substances were concentrated in the spinosal and basal epidermal layers, additionally marked by D-galactose. The eccrine glands exhibited high amounts of mainly neutral glycoconjugates in the secretory portion, especially in the wolf. A clear spectrum of saccharide residues was demonstrable in the dark cells (alpha-D-mannose, beta-N-acetyl-D-glucosamine, alpha-N-acetyl-D-galactosamine, alpha-D-galactose), and in the clear cells which lacked mannose and contained beta-D-galactose. In contrast to the wolf, strong reactions for glycoconjugates were visible among intercellular substances of intradermal excretory duct cells in the dog. Only in the wolf did the periphery of the intracorneal excretory ducts and the outer surface of the foot pads show clearly positive reactions for glycoconjugates. The results obtained are discussed with regard to the specific functions of the body regions investigated and the behavioural biology of the Canidae. It is obvious that differences in amounts, quality, and localization of the glycoconjugates produced exist between the wolf and its domesticated descendant.