Sialic acids and antimicrobial substances in the apocrine glands of porcine perianal skin.

The porcine perianal skin shows prominent apocrine glands with large saccular dilatations, whereby the functional significance of the glandular secretions is rather unexplained. Our study focuses on the demonstration of sialoglycoconjugates and antimicrobial substances in these glands, using glycoconjugate histochemical and immunohistochemical methods. The result obtained emphasized the general presence of sialic acids, linked to α2-6Gal/GalNAc and α2-3Gaβl1-4GlcNAc, in the secretory cells. The secretory epithelium and luminal secretions also contained a spectrum of antimicrobial substances, such as lysozyme, IgA, lactoferrin, and the peptide group of β-defensins. Realizing that sialic acids possess diverging functional properties through various saccharide residues, and that antimicrobial substances serve as a non-specific defense against microorganisms, these secretory products may function as protective agents in order to preserve the integrity of the perianal region. This view includes that the amounts of bacteria on the skin surface are controlled and maintained at the certain level.