Composition and properties of human cervical mucus. I. Electrophorectic separation and identification of proteins.

The importance of cervical mucus in female infertility is generally recognized (1). Clinical characteristics of human cervical mucus have been the subject of many studies in recent years. However, very little is known about the chemical composition or the biological significance of this epithelial secretion. Cervical mucus normally contains from 92 to 94 per cent water in the preand post-ovulatory phases, while in midcycle the water content rises to 98 per cent (2). The primary constituent is believed to be a mucopolysaccharide composed of galactose and hexosamine as well as some fucose and sialic acid (3, 4). Recent experiments with S35-labeled sulfate have shown the presence of sulfate in the cervical mucus of rabbit and guinea pigs (5, 6). Both human and rabbit cervical gland and secretions react metachromatically with toluidine blue (7-9), indicating the presence of an acid mucopolysaccharide. The absence of uronic acid and the lack of effect by testicular hyaluronidase on cervical mucus eliminates the probability that this mucopolysaccharide is either hyaluronic acid or one of the chondroitin sulfates. If the sulfate groups are bound to mucopolysaccharides, which has not been proven, it seems likely that they are from keratosulfate, a sulfated polysaccharide composed of galactose and glucQsamine (9, 10). The presence of proteins in the cervical mucus is generally conceded (3, 4, 10). Pommerenke found that cervical mucus gave a positive biuret test and positive reactions for tryptophan, tyrosine and cysteine (2). Werner determined the total nitrogen content of the pooled cervical mucus to be 12.1 per cent (4). This, in part, represented protein(s) which could be digested by trypsin, and