[Variation of the sialic acid-protein ratio in the human cervical mucus (author's transl)].

Serial determinations of total protein and sialic acid concentrations were carried out in individual cervical mucus samples of normal women, throughout the menstrual cycle as well as under the influence of estrogen and progestagen steroids. Total protein was titrated by a modified micro-biuret method and sialic acid was determined using the "Direct Ehrlich" method. Both parameters diminished gradually during the follicular phase of the cycle with lowest values around the time of ovulation, and showed a strong increase during the luteal phase. Administration of ethinylestradiol yielded values significantly lower than those of normal ovulatory phase and under d-Nosgestrel treatment the values were significantly higher than in normal luteal phase. However the proportion of sialic acid as related to total protein showed an inverse behavior, i.e. increased under estrogenic and decreased under progestogenic influence. The cyclic and hormone-induced variations of this ratio were more specific than those of both separate components. Thus, estrogens produce an increase of the sialic acid containing fraction of cervical mucus proteins, while progestagens have an opposite effect. The role of these actions in reproductive physiology is discussed.