The sweat gland as a mucous gland

Human crude sweat and sweat from a rhesus monkey (<i>Macaca mulatta</i>), obtained from the skin after thermal stimulation, were compared with human saliva and skin mucus from the frog (<i>Rana temporaria</i>) and eel (<i>Anguilla</i>). Mucin from all samples contained sialic acid and small amounts of lipids and protein; the polysaccharide part was essentially sulfated and contained but little hexuronic acid and hexosamine. Hydrolysed mucin fractions from all materials showed a similar amino acid composition. The skin mucins differed from other mucins in amino acid composition by the absence of threonine. Human crude sweat from the chest contained acid phosphatase, monkey sweat acid and alkaline phosphatase, frog skin mucus alkaline phosphatase and eel skin mucus acid phosphatase. Human axillar crude sweat showed a considerable alkaline phosphatase activity in addition to a stronger acid phosphatase activity than that from the chest. In atopic dermatitis no difference appeared in sialic acid content with a control group and a difference in protein content of mucin was unlikely. In this disease the significantly larger variability in free phosphate content was presumably from intra-cellular origin and that in the results of a reaction employing sulfite and heptazine indicated the importance of an investigation into lipids, containing carbonyl groups, in skin mucin.