Cyclic changes of cervical mucus enzymes related to the time of ovulation. I. Alkaline phosphatase

Light Microscopy and Proteomic Patterns of Ovulation in Cervical Mucus

There is an increasing number of couples interested in identifying the fertile window for the purpose of conceiving. From what has been published so far, it can be concluded that there are no reliable methods to predict ovulation, and, therefore, to predict the fertile window. Proteins of the cervical mucus (CM) could behave as biomarkers to allow the early and precise identification of ovulation. CM samples were collected from the lumen of the cervical canal from women of reproductive age, on three different days of the same menstrual cycle. Samples were first analyzed and classified by light microscopy. High-resolution mass spectrometry and bioinformatic analysis were performed afterwards to determine the in vivo changes of CM protein composition. CM underwent cyclical changes in its biophysical composition, which were evidenced by changes in the crystallographic patterns observed under the light microscope. The proteomic analysis revealed changes in the protein composition of CM along the cycle. Twenty-five out of the forty-eight total proteins identified could become potential biomarkers of ovulation. The coordinated changes in the composition of the CM around the time of ovulation could be happening to specifically grant access to a foreign body, such as the sperm might be.

Identification and characterisation of O-linked glycans in cervical mucus as biomarkers of sperm transport: A novel sheep model

Cervical mucus plays an important role in female fertility, since it allows the entry of motile and morphological normal sperm while preventing the ascent of pathogens from the vagina. The function of cervical mucus is critically linked to its rheological properties that are in turn dictated by O-glycosylated proteins, called mucins. We aimed to characterize the O-glycan composition in the cervical mucus of six European ewe breeds with known differences in pregnancy rates following cervical/vaginal artificial insemination with frozen–thawed semen, which are due to reported differences in cervical sperm transport. These were Suffolk (low fertility) and Belclare (medium fertility) in Ireland, Ile de France and Romanov (both with medium fertility) in France, and Norwegian White Sheep (NWS) and Fur (both with high fertility) in Norway (n = 28–30 ewes/breed). We identified 124 O-glycans, from which 51 were the major glycans with core 2 and fucosylated glycans as the most common structures. The use of exogenous hormones for synchronization did not affect the O-glycan composition in both high-fertility ewe breeds, but it did in the other four ewe breeds. There was a higher abundance of the sulfated glycan (Galβ1–3[SO3-GlcNAcβ1–6]GalNAc), fucosylated glycan (GlcNAcβ1–3(Fucα1–2Galβ1–3)GalNAc) and core 4 glycan (GlcNAcβ1–3[GlcNAcβ1–6]GalNAc) in the low-fertility Suffolk breed compared with NWS (high fertility). In addition, core 4 glycans were negatively correlated with mucus viscosity. This novel study has identified O-glycans that are important for cervical sperm transport and could have applications across a range of species including human.

The role of the cervix in fertility: is it time for a reappraisal?

Knowledge regarding the role of the cervix in fertility has expanded considerably over the past 20 years and in this article, we propose that it is now time for its function to be reappraised. First, we review the anatomy of the cervix and the vaginal ecosystem that it inhabits. Then, we examine the physiology and the role of the cervical mucus. The ongoing mystery of the exact mechanism of the sperm-cervical mucus interaction is reviewed and the key players that may unlock this mystery in the future are discussed. The soluble and cellular biomarkers of the lower female genital tract which are slowly being defined by contemporary research are reviewed. Attempts to standardize these markers, in this milieu, are hindered by the changes that may be attributed to endogenous or exogenous factors such as: age, hormonal changes during the menstrual cycle, ectropion, infection, smoking and exposure to semen during sexual intercourse. We review what is known about the immunology of the cervix. With the widespread use of large loop excision of the transformation zone (LLETZ) for treatment of cervical intraepithelial neoplasia, the anatomy of the cervix is changing for many women. While LLETZ surgery has had very positive effects in the fight against cervical cancer, we debate the impact it could have on a woman's fertility.

Alterations in protein, sialic acid and some enzymes in cervical mucus of female rats during NET-EN treatment

The effect of norethisterone enanthate (NET-EN) on cervical mucus protein, sialic acid and some enzymes (e.g. peroxidase, alkaline phosphatase and alpha-amylase) were studied in adult female rats. One mg NET-EN every 12 days was found to be an effective contraceptive dose of this drug in this species, acting primarily through the cervical mucus. NET-EN produced a highly significant increase in protein content and peroxidase and alkaline phosphatase activities. However, sialic acid content and amylase activity did not exhibit any definite pattern after NET-EN therapy. The increased protein content together with persistent elevated levels of peroxidase and alkaline phosphatase corroborates the hypothesis that NET-EN creates a progestogenic phase which prevents sperm penetration and thus conception.

Cervical mucus peroxidase is a reliable indicator for ovulation in humans

This study was designed to establish whether fluctuation in cervical mucus peroxidase concentration correlates with the cyclic pattern of the menstrual cycle hormones in the human female. Forty healthy, normal-cycling women between the ages of 19 and 29 years were chosen for the study. Blood samples and cervical mucus were collected on days 6, 9 through 15, and 17 through 19 of the menstrual cycle for three consecutive cycles in each volunteer. Blood estrogen, progesterone, follicle-stimulating hormone, and luteinizing hormone levels were quantitated by radioimmunoassay, and cervical mucus peroxidase concentrations were measured spectrophotometrically. The data showed that in the typical menstrual cycle the mucus peroxidase peak was reached immediately prior to the luteinizing hormone/follicle-stimulating hormone surge and coincided with the estrogen peak. Consistent data in three consecutive menstrual cycles in each volunteer led us to postulate that the mucus peroxidase peak during the menstrual cycle precedes the ovulatory period in the normal healthy woman.

Cyclic changes of sialidase in human cervical mucus

1. Sialidase activity is detectable in whole cervical mucus of normal women throughout the menstrual cycle and presents cyclic variations toward endogenous and exogenous substrates. 2. The level of sialic acid bound to the mucus increases progressively till mid-cycle and declines in the post-ovulatory phase. 3. The sialidase of the mucus probably derives from different sources and its role remains speculative.

Lactate dehydrogenase in human cervical mucus: correlation with ovulation, influence of ovarian steroid hormones, and isozyme pattern

The glycolytic enzymes, lactate dehydrogenase (LDH), glucose-6-phosphate dehydrogenase, and hexokinase in cervical mucus of 96 ovulatory women were serially measured daily during the menstrual cycle. Among all of the enzymes, the cyclic changes in LDH activity were the most significant, being high during the proliferative phase, gradually decreasing to the lowest level around ovulation, and then increasing markedly again. Estrogen inhibited cervical mucus LDH activity; progestrone accelerated it. Examination of the LDH isozyme pattern showed that H-LDH (H-subunit of LDH), being predominant throughout the cycle, apparently carries some responsibility for the cyclic change in LDH activity. In a comparison of LDH activity with the serum luteinizing hormone (LH) peak, the activity level nadir of LDH usually appeared between 1 day before and 1 day after the serum LH peak, pointing to the advantage of daily measurement of cervical mucus LDH activity for predicting the potential day of conception.