The function of the cervix in fertility

Female sexual function and distress and time-to-pregnancy in a prospective preconception cohort

BACKGROUND

Fertility success among mixed-sex couples often depends on frequency and timing of sexual intercourse, yet little research has evaluated the association between preconception sexual function and time-to-pregnancy.

OBJECTIVE

To evaluate the effects of female sexual dysfunction, distress related to sexual functioning, and painful intercourse on time-to-pregnancy.

STUDY DESIGN

We followed 2500 participants from Pregnancy Study Online, a prospective cohort study of self-identified females attempting pregnancy without the use of fertility treatments. Participants enrolled between 2021 and 2024. Thirty days after enrollment, participants completed a supplemental questionnaire that contained questions about sexual health, including a modified version of the 6-item Female Sexual Function Index (score range 2-30, score ≤19 defined as sexual dysfunction) and the Female Sexual Distress Scale (score range 0-48, score ≥20 defined as clinically relevant distress), which assess experiences in the previous 4 weeks. Participants completed the supplemental questionnaire no later than 6 months after initiating conception attempts. We estimated time-to-pregnancy based on self-reported pregnancy status on follow-up questionnaires completed every 8 weeks for up to 12 months. We used proportional probabilities regression to calculate fecundability ratios and 95% confidence intervals relating exposure measures with time-to-pregnancy, adjusting for a range of prespecified confounders. As an exploratory analysis, we evaluated individual domains of sexual function (ie, interest, arousal, orgasm, lubrication, and satisfaction) in relation to time-to-pregnancy.

RESULTS

The study population was primarily non-Hispanic White, high income, with college or graduate education. Exposure prevalence was 20.1% for female sexual dysfunction, 8.8% for distress, and 29.6% for any pain with intercourse. We observed no association between female sexual dysfunction and time-to-pregnancy (adjusted fecundability ratio 1.00, 95% confidence interval 0.890, 1.13) when female sexual dysfunction was defined using a clinically validated cut point, but observed that those in the first, second, and third quartile of scores had delayed conception compared to those in the fourth (highest function) (adjusted fecundability ratios 0.90, 95% confidence interval 0.76, 1.06; 0.88, 95% confidence interval 0.75, 1.04; and 0.90, 95% confidence interval 0.77, 1.04, respectively). We found 18% reduced fecundability among those with sexual distress as defined by a clinically validated cut point compared to those without (adjusted fecundability ratio 0.82, 95% confidence interval 0.69, 0.98). Participants reporting painful intercourse most or all the time had a longer time-to-pregnancy than those reporting no pain (adjusted fecundability ratio 0.81, 95% confidence interval 0.62, 1.06). In exploratory analyses, lower function in orgasm and lubrication domains, but not interest, desire, and arousal, were associated with longer time-to-pregnancy.

CONCLUSION

Preconception sexual dysfunction, specifically distress and frequent painful intercourse, was associated with delayed conception. Preconception clinical assessment of sexual function, including discussion of individual domains of sexual function, may elucidate important modifiable issues.

The effectiveness of cervical mucus electrical impedance compared to basal body temperature to determine fertility window

BACKGROUND

Serial serum hormone measurements and transvaginal ultrasound are reliable measures to predict ovulation. These measures are inconvenient and expensive therefore, basal body temperature charting (BBT) and urine ovulation predictor kits (OPK) for luteinizing hormone are often used to determine the 6-day fertile window. However, BBT does not clearly change until 1-2 days after ovulation. Additionally, while OPK can indicate positivity prior to ovulation, false readings are common. A novel alternative approach involves measuring electrolyte trends in cervical mucus using electrical impedance spectroscopy. Cervical mucus electrolyte measurements are associated with hormone level changes during the menstrual cycle. The purpose of this study was to compare the effectiveness of cervical mucus electrical impedance and basal body temperature. We sought to determine if cervical mucus electrolyte measurements provided improved detection of the ovulation day and therefore, improve fertility timing for women.

METHODS

14 healthy women between 18 and 44 years of age with normal menstrual cycles were enrolled in the Observational Study. Participants measured BBT and cervical mucus electrical impedance daily for 3 menstrual cycles using Kegg (Lady Technologies Inc. San Francisco, California, USA). Ovulation date for each cycle was confirmed by measuring hormone levels in urine and serum, and by vaginal ultrasound.

RESULTS

Electrical impedance was significantly different between the follicular phase versus ovulatory date (p = 0.007) and between the luteal phase versus the ovulatory date (p = 0.007). A significant difference in the rate of change of cervical impedance measurements in the pre-ovulatory follicular phase was found compared to BBT (p = 0.0225). The sensitivity (+ 7.14%), specificity (+ 20.35%), and accuracy (+ 17.59) to determine the 1-day fertility window was significantly higher using cervical mucus impedance compared to BBT.

CONCLUSIONS

BBT is considered unreliable for evaluating ovulatory function. Cervical mucus electrical impedance offers a novel measure of electrolyte changes associated with hormone levels. We report that pre-ovulatory electrical impedance patterns demonstrated higher sensitivity, specificity, and accuracy for determining the fertility window when compared to BBT. These findings suggest that changes in electrical impedance may provide an accurate method for predicting ovulation and for measuring ovulatory function.

The yielding behaviour of human mucus

Mucus is a viscoelastic material with non-linear rheological properties such as a yield stress of the order of a few hundreds of millipascals to a few tens of pascals, due to a complex network of mucins in water along with non-mucin proteins, DNA and cell debris. In this review, we discuss the origin of the yield stress in human mucus, the changes in the rheology of mucus with the occurrence of diseases, and possible clinical applications in disease detection as well as cure. We delve into the domain of mucus rheology, examining both macro- and microrheology. Macrorheology involves investigations conducted at larger length scales (∼ a few hundreds of μm or higher) using traditional rheometers, which probe properties on a bulk scale. It is significant in elucidating various mucosal functions within the human body. This includes rejecting unwanted irritants out of lungs through mucociliary and cough clearance, protecting the stomach wall from the acidic environment as well as biological entities, safeguarding cervical canal from infections and providing a swimming medium for sperms. Additionally, we explore microrheology, which encompasses studies performed at length scales ranging from a few tens of nm to a μm. These microscale studies find various applications, including the context of drug delivery. Finally, we employ scaling analysis to elucidate a few examples in lung, cervical, and gastric mucus, including settling of irritants in lung mucus, yielding of lung mucus in cough clearance and cilial beating, spreading of exogenous surfactants over yielding mucus, swimming of Helicobacter pylori through gastric mucus, and lining of protective mucus in the stomach. The scaling analyses employed on the applications mentioned above provide us with a deeper understanding of the link between the rheology and the physiology of mucus.

Investigating the relationship between the cervical mucoprotein levels and cervical intraepithelial neoplasia

BACKGROUND

Cervical cancer has been ranked as the fourth most common cancer in women. The role of HPV, the DNA virus identified in the 1980s, in almost all cervical cancers is undisputed. In patients scanned with smear and HPV, a cervical biopsy is performed accompanied by colposcopic examination, and the lesion is defined. The concentration of mucoproteins varies in the structure of the cervical mucus with neoplasms. The major aim of this study was to investigate the changes in the levels of cervical mucoprotein in patients at the early stages of cervical cancer and evaluate if these levels can be used in the early diagnosis of this cancer type.

METHODS

The study was designed as a prospective cohort study. Samples from cervical mucus were taken and stored before colposcopy examination of human papillomavirus (HPV) positive patients (N.=100). According to the pathology results, while 36 cases constituted the precancerous group, no suspicion of cancer was found in 64 cases. To ensure standardization, colposcopy was performed immediately after the menstrual cycle and at least 0.5 mL of the cervical mucus sample was taken from all individual patients used in this study. Cervical mucus samples of the patients were analyzed for mucoproteins MUC1, MUC2, MUC5AC and MUC5B.

RESULTS

All mucoprotein levels were found to be higher in patients with cervical intraepithelial neoplasia (CIN) than those of subjects with normal pathology for cervical neoplasia.

CONCLUSIONS

Significant relationship was obtained between cervical intraepithelial neoplasms and the levels of mucoproteins in cervical mucus. The results showed that diagnosis of neoplasia with HPV may be easily performed by utilizing any mucoprotein test.

Cervical mucus patterns and the fertile window in women without known subfertility: a pooled analysis of three cohorts

STUDY QUESTION

What is the normal range of cervical mucus patterns and number of days with high or moderate day-specific probability of pregnancy (if intercourse occurs on a specific day) based on cervical mucus secretion, in women without known subfertility, and how are these patterns related to parity and age?

SUMMARY ANSWER

The mean days of peak type (estrogenic) mucus per cycle was 6.4, the mean number of potentially fertile days was 12.1; parous versus nulliparous, and younger nulliparous (<30 years) versus older nulliparous women had more days of peak type mucus, and more potentially fertile days in each cycle.

WHAT IS KNOWN ALREADY

The rise in estrogen prior to ovulation supports the secretion of increasing quantity and estrogenic quality of cervical mucus, and the subsequent rise in progesterone after ovulation causes an abrupt decrease in mucus secretion. Cervical mucus secretion on each day correlates highly with the probability of pregnancy if intercourse occurs on that day, and overall cervical mucus quality for the cycle correlates with cycle fecundability. No prior studies have described parity and age jointly in relation to cervical mucus patterns.

STUDY DESIGN, SIZE, DURATION

This study is a secondary data analysis, combining data from three cohorts of women: 'Creighton Model MultiCenter Fecundability Study' (CMFS: retrospective cohort, 1990-1996), 'Time to Pregnancy in Normal Fertility' (TTP: randomized trial, 2003-2006), and 'Creighton Model Effectiveness, Intentions, and Behaviors Assessment' (CEIBA: prospective cohort, 2009-2013). We evaluated cervical mucus patterns and estimated fertile window in 2488 ovulatory cycles of 528 women, followed for up to 1 year.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Participants were US or Canadian women age 18-40 years, not pregnant, and without any known subfertility. Women were trained to use a standardized protocol (the Creighton Model) for daily vulvar observation, description, and recording of cervical mucus. The mucus peak day (the last day of estrogenic quality mucus) was used as the estimated day of ovulation. We conducted dichotomous stratified analyses for cervical mucus patterns by age, parity, race, recent oral contraceptive use (within 60 days), partial breast feeding, alcohol, and smoking. Focusing on the clinical characteristics most correlated to cervical mucus patterns, linear mixed models were used to assess continuous cervical mucus parameters and generalized linear models using Poisson regression with robust variance were used to assess dichotomous outcomes, stratifying by women's parity and age, while adjusting for recent oral contraceptive use and breast feeding.

MAIN RESULTS AND THE ROLE OF CHANCE

The majority of women were <30 years of age (75.4%) (median 27; IQR 24-29), non-Hispanic white (88.1%), with high socioeconomic indicators, and nulliparous (70.8%). The mean (SD) days of estrogenic (peak type) mucus per cycle (a conservative indicator of the fertile window) was 6.4 (4.2) days (median 6; IQR 4-8). The mean (SD) number of any potentially fertile days (a broader clinical indicator of the fertile window) was 12.1 (5.4) days (median 11; IQR 9-14). Taking into account recent oral contraceptive use and breastfeeding, nulliparous women age ≥30 years compared to nulliparous women age <30 years had fewer mean days of peak type mucus per cycle (5.3 versus 6.4 days, P = 0.02), and fewer potentially fertile days (11.8 versus 13.9 days, P < 0.01). Compared to nulliparous women age <30 years, the likelihood of cycles with peak type mucus ≤2 days, potentially fertile days ≤9, and cervical mucus cycle score (for estrogenic quality of mucus) ≤5.0 were significantly higher among nulliparous women age ≥30 years, 1.90 (95% confidence interval (CI) 1.18, 3.06); 1.46 (95% CI 1.12, 1.91); and 1.45 (95% CI 1.03, 2.05), respectively. Between parous women, there was little difference in mucus parameters by age. Thresholds set a priori for within-woman variability of cervical mucus parameters by cycle were examined as follows: most minus fewest days of peak type mucus >3 days (exceeded by 72% of women), most minus fewest days of non-peak type mucus >4 days (exceeded by 54% of women), greatest minus least cervical mucus cycle score >4.0 (exceeded by 73% of women), and most minus fewest potentially fertile days >8 days (found in 50% of women). Race did not have any association with cervical mucus parameters. Recent oral contraceptive use was associated with reduced cervical mucus cycle score and partial breast feeding was associated with a higher number of days of mucus (both peak type and non-peak type), consistent with prior research. Among the women for whom data were available (CEIBA and TTP), alcohol and tobacco use had minimal impact on cervical mucus parameters.

LIMITATIONS, REASONS FOR CAUTION

We did not have data on some factors that may impact ovulation, hormone levels, and mucus secretion, such as physical activity and body mass index. We cannot exclude the possibility that some women had unknown subfertility or undiagnosed gynecologic disorders. Only 27 women were age 35 or older. Our study participants were geographically dispersed but relatively homogeneous with regard to race, ethnicity, income, and educational level, which may limit the generalizability of the findings.

WIDER IMPLICATIONS OF THE FINDINGS

Patterns of cervical mucus secretion observed by women are an indicator of fecundity and the fertile window that are consistent with the known associations of age and parity with fecundity. The number of potentially fertile days (12 days) is likely greater than commonly assumed, while the number of days of highly estrogenic mucus (and higher probability of pregnancy) correlates with prior identifications of the fertile window (6 days). There may be substantial variability in fecundability between cycles for the same woman. Future work can use cervical mucus secretion as an indicator of fecundity and should investigate the distribution of similar cycle parameters in women with various reproductive or gynecologic pathologies.

STUDY FUNDING/COMPETING INTEREST(S)

Funding for the three cohorts analyzed was provided by the Robert Wood Johnson Foundation (CMFS), the Eunice Kennedy Shriver National Institute of Child Health and Human Development (TTP), and the Office of Family Planning, Office of Population Affairs, Health and Human Services (CEIBA). The authors declare that they have no conflict of interest.

TRIAL REGISTRATION NUMBER

N/A.

Treatment Strategies for Unexplained Infertility

Unexplained infertility is a common diagnosis among couples with infertility. Pragmatic treatment options in these couples are directed at trying to improve chances to conceive, and consequently intrauterine insemination (IUI) with ovarian stimulation and in vitro fertilization (IVF) are standard clinical practice, while expectant management remains an important alternative. While evidence on IVF or IUI with ovarian stimulation versus expectant management was inconclusive, these interventions seem more effective in couples with a poor prognosis of natural conception. Strategies such as strict cancellation criteria and single-embryo transfer aim to reduce multiple pregnancies without compromising cumulative live birth. We propose a prognosis-based approach to manage couples with unexplained infertility so as to expose less couples to unnecessary interventions and less mothers and children to the potential adverse effects of ovarian stimulation or laboratory procedures.

Uterine Immunity and Microbiota: A Shifting Paradigm

The female reproductive tract harbors distinct microbial communities, as in the vagina, cervical canal, uterus, and fallopian tubes. The nature of the vaginal microbiota is well-known; in contrast, the upper reproductive tract remains largely unexplored. Alteration in the uterine microbiota, which is dependent on the nutrients and hormones available to the uterus, is likely to play an important role in uterine-related diseases such as hysteromyoma, adenomyosis, and endometriosis. Uterine mucosa is an important tissue barrier whose main function is to offer protection against pathogens and other toxic factors, while maintaining a symbiotic relationship with commensal microbes. These characteristics are shared by all the mucosal tissues; however, the uterine mucosa is unique since it changes cyclically during the menstrual cycle as well as pregnancy. The immune system, besides its role in the defense process, plays crucial roles in reproduction as it ensures local immune tolerance to fetal/paternal antigens, trophoblast invasion, and vascular remodeling. The human endometrium contains a conspicuous number of immune cells, mainly Natural Killers (NK) cells, which are phenotypically distinct from peripheral cytotoxic NK, cells and macrophages. The endometrium also contains few lymphoid aggregates comprising B cell and CD8⁺ T cells. The number and the phenotype of these cells change during the menstrual cycle. It has become evident in recent years that the immune cell phenotype and function can be influenced by microbiota. Immune cells can sense the presence of microbes through their pattern recognition receptors, setting up host-microbe interaction. The microbiota exerts an appropriately controlled defense mechanism by competing for nutrients and mucosal space with pathogens. It has recently been considered that uterus is a non-sterile compartment since it seems to possess its own microbiota. There has been an increasing interest in characterizing the nature of microbial colonization within the uterus and its apparent impact on fertility and pregnancy. This review will examine the potential relationship between the uterine microbiota and the immune cells present in the local environment.

Immune Aspects of Female Infertility

Immune infertility, in terms of reproductive failure, has become a serious health issue involving approximately 1 out of 5 couples at reproductive age. Semen that is defined as a complex fluid containing sperm, cellular vesicles and other cells and components, could sensitize the female genital tract. The immune rejection of male semen in the female reproductive tract is explained as the failure of natural tolerance leading to local and/or systemic immune response. Present active immune mechanism may induce high levels of anti-seminal/sperm antibodies. It has already been proven that iso-immunization is associated with infertility. Comprehensive studies with regards to the identification of antibody-targets and the determination of specific antibody class contribute to the development of effective immuno-therapy and, on the other hand, potential immuno-contraception, and then of course to complex patient diagnosis. This review summarizes the aspects of female immune infertility.

[The mucus: a medium of life]

OBJECTIVES

To investigate whether mucus, with its complex structure and specific functional properties, is a medium for life?

PATIENTS AND METHODS

We compared cervical and nasal mucus samples collected from 45 ovulatory women consulting for sterility and 5 menopausal women respectively. We analyzed the physicochemical and functional characteristics. We also performed 266 sperm penetrability tests. We studied 32 samples using scanning electron microscope, according to Hexamethyl-Disilasane technique and the critical point drying method.

RESULTS

Both types of mucus had 10cm spin abilities and typical ferning patterns. The pH were similar (8.09±0.58 and 8.46±0.32 for cervical and nasal mucus, respectively) as well as the percentages of positive sperm penetration test (55.6 and 40.6 respectively). We observed similar patterns of spermatozoa mobility in both types of mucus. Under the scanning electron microscope, structures resembled woven fabric, with a stretched and rigid framework. Filaments of different diameters formed variable loose meshes. Thinner filaments linked together thicker filaments measuring between 300 and 400nm. The intermediate filaments varied between 100 and 200nm. Very thin and sparse filaments crossed the meshes, measuring between 10 to 100nm. Spermatozoa, bacteria and unspecified round cells were enmeshed in the mucus.

DISCUSSION AND CONCLUSION

From this first comparative study of nasal and cervical mucus giving the proof of sperm penetration in the both mucus and the discovery of mucus produced by archaea living in extreme conditions, we suggested that mucus, from all origins, is a medium of life.

Globular structure of human ovulatory cervical mucus

Human cervical mucus is a heterogeneous mixture of mucin glycoproteins whose relative concentration changes during the ovulatory phases, thereby producing different mucus aggregation structures that can periodically permit the transit of spermatozoa for fertilization. In preovulatory phase, mucus is arranged in compact fiber-like structures where sperm transit is hindered. Previously, through observations made of fixed and dehydrated samples, a permissive structure in the ovulatory phase was attributed to the larger diameters of pores in the mucus network. Instead, by means of atomic force microscopy, we can show, for the first time, that unfixed ovulatory mucus is composed by floating globules of mucin aggregates. This finding sheds new light on the mechanism that governs spermatozoa transit toward the uterine cavity. In addition, we demonstrate that the switch from globular ovulatory to fibrous preovulatory mucus largely depends on a pH-driven mechanism. Analysis of mucin 5B primary sequence, the main mucin in ovulatory mucus, highlights pH-sensitive domains that are associated to flexible regions prone to drive aggregation. We suggest an involvement of these domains in the fiber-to-globule switch in cervical mucus.

Role of sialic acid and sulfate groups in cervical mucus physiological functions: study of Macaca radiata glycoproteins

The influence of charged groups in glycoproteins was investigated to assess their effect on the physiological functions of bonnet monkey cervical mucus. The macromolecular glycoproteins from peri-ovulatory, midcycle phase cervical mucus were treated with Pronase, trypsin and chymotrypsin and the enzyme-resistant glycoproteins purified by gel filtration on Sepharose 4B and a high molecular weight component containing carbohydrates, proteins and sulfate groups was recovered in high yield. This material still reacted with an antiserum directed against purified midcycle glycoprotein but not against another antiserum directed against luteal phase purified glycoproteins. Upon treatment with Pronase, trypsin and chymotrypsin, asialoglycoproteins and desulfated asialoglycoproteins released fragments of low molecular sizes, none of which reacted with the anti-midcycle glycoprotein antiserum. Cervical mucus collected from the estrogenic phase displayed a morphology supporting sperm migration, and this mucus retains the same morphology and reacts with the anti-midcycle glycoprotein antiserum following mild treatment with sialidase and subsequently with Pronase. These results imply that charged carbohydrate groups help maintain the structural and functional integrity of the mucus glycoprotein in its biological environment.

Chemical properties of bovine cervical mucus during normal estrus and estrus induced by progesterone and/or PGF2alpha

Ninety-two Friesian cows were used to determine the chemical properties of cervical mucus during normal estrus and estrus induced by progesterone (P4)-releasing intravaginal devices (PRID) and/or prostaglandin F2alpha. The animals were assigned to 4 groups (no treatment, a PRID for 12 days plus injection of 1000 IU PMSG at the removal of PRID, a double i.m. injection of PGF2alpha 11 days apart, or PRID for 7 days plus an im injection of PGF2alpha 24 h before the removal of PRID). A number of cows with normal estrus exhibited three consecutive estrous cycles after delivery. Cows that had not shown estrus for 3 months after delivery had their ovaries palpated twice at 10-day intervals, to determine their ovarian activity. Then PRID and/or PGF2alpha was administered in cows that had a palpable corpus luteum in one of the two palpations (cyclic cows). A double artificial insemination (AI) was performed to the cows of the three induced-estrus groups, while the cows with normal estrus received only one AI. Cervical mucus samples were collected from all cows 5 to 30 min before the first AI. Additionally, samples of cervical mucus were collected from 20 cows during their first estrus after the induced one. The results are summarized as follows: 1) The biochemical properties of cervical mucus in the first three estrus periods after delivery were similar. 2) These properties were similar both in normal estrus after delivery and in the first estrus after an induced one. 3) Glucose and fructose concentrations for normal estrus were similar to those for induced estrus groups. 4) Total protein and cholesterol concentrations were significantly lower (P < 0.001) in normal than in induced estrus, while no difference was found among the induced estrus groups. 5) Pregnancy rates of the cows did not differ significantly among the normal and the induced-estrus groups. 6) The percentages of cows in the induced-estrus groups that produced cervical mucus with total protein and cholesterol concentrations similar to those for the normal estrus groups was very low.

Physical properties of bovine cervical mucus during normal and induced (progesterone and/or PGF2alpha) estrus

Ninety two Friesian cows were used to determine physical properties of cervical mucus collected during normal estrus and estrus induced. Estrus was induced using either progesterone (P4) releasing intravaginal devices (PRID) and/or prostaglandin F2alpha (PGF2alpha). The animals were assigned to 4 groups (no treatment, a PRID for 12 days plus an injection of 1000 IU PMSG at the removal of the PRID, a double injection of 3 mL PGF2alpha 11 days apart, and a PRID for 7 days plus an injection of PGF2alpha 24 h before the removal of PRID). A number of cows with normal estrus exhibited three consecutive estrus cycles after calving. Cows that had not shown estrus for three months after calving had their reproductive system palpated twice at 10-day intervals, to determine their ovarian activity. Then PRID and/or PGF2alpha was administered to cows that were found to have a palpable corpus luteum in one of two palpations (cycling cows). The cows of the three induced estrous groups were artificially inseminated (AI) twice, while those with normal estrus received only a single AI. Cervical mucus samples were collected from all cows 5 to 30 min before the first AI. Additionally, samples of cervical mucus were collected from 20 cows at their first estrus after the induced estrus. The results are summarized as follows: 1) The physical properties of cervical mucus were similar in the first three normal consecutive estrus cycles after calving. 2) The physical properties of cervical mucus in normal estrus after calving were similar to those in the first estrus after an induced estrus. 3) The pH values for normal estrus were similar to those for induced estrus. 4) Viscosity of cervical mucus in the normal estrous group was significantly lower than that in the induced estrus. Furthermore, significant differences were noticed among the three induced estrous groups. 5) Spinnbarkeit, crystallization and receptivity of cervical mucus (penetration test) were significantly higher in the normal estrous group than in the induced estrous groups, while no difference was detected among induced estrus groups. 6) Pregnancy rates in the normal estrus group were the same as in the induced estrus groups. 7) The percentages of cows in the induced estrous groups that produced cervical mucus with similar viscosity, spinnbarkeit and receptivity (penetration test) characteristics as the normal estrus group, was very low.

Comparison of human cervical mucus and artificial sperm penetration media

The cervical mucus penetration tests aid research and determine the clinical importance of positive sperm antibody tests. Limited availability and variability of human cervical mucus have instigated the search for mucus substitutes for these tests. This study compares sperm migration in cervical mucus with that in artificial media including hyaluronate solution, egg white and albumin Tyrode solution. Results were quantified by measuring the migration distance (the maximum distance of capillary migration from a semen reservoir by spermatozoa after 1 h) and the sperm concentration at half the migration distance. The mean of both measures for cervical mucus and hyaluronate solution were equivalent [4.4 +/- 1.1 (SD) versus 4.3 +/- 1.0 cm and 118 +/- 51 versus 111 +/- 44x10(3)/ml], and higher than in egg white and albumin Tyrode solution. Antisperm antibodies impaired sperm penetration in cervical mucus and hyaluronate solution in a similar manner (r = 0.92). These results suggest that hyaluronate solution sufficiently resembles human cervical mucus in terms of penetrability that it may be used as a substitute for mucus in capillary tube tests of sperm function. The higher penetrability of cervical mucus and hyaluronate solution is probably related to a channelling effect due to their polymeric structure.

An evaluation of the amount of nonoxynol-9 remaining in the vagina up to 4 h after insertion of a vaginal contraceptive film (VCF) containing 70 mg nonoxynol-9

The objectives of this study were to determine the amount of nonoxynol-9 (N-9) remaining in the vagina 30 min and 1, 1.5, 2, and 4 h after vaginal insertion of a single sheet of VCF containing 70 mg N-9 and to compare these results to the manufacturer's instructions for use of this product. A new method of vaginal lavage was used to obtain samples for N-9 determination. This was an open-label, noncomparative, pharmacokinetic study in 12 healthy women volunteers not at risk for pregnancy. The study consisted of a screening visit followed by five test visits approximately 1 month apart and a final visit 1 week after all test visits were completed. At each test visit, the investigator inserted a single sheet of VCF in the vagina of the volunteer at midcycle. The volunteer remained in the clinic and underwent vaginal lavage with normal saline after one of five specified time intervals had elapsed. The sequence of the intervals completed by each volunteer was determined by randomization. When undissolved film was found in the vagina, it was removed prior to lavage and assayed for N-9 content separately from that recovered in lavage fluid. It was assumed that the N-9 in undissolved film would not contribute significantly to sperm immobilization. Between 18.5 and 28.5 mg of N-9 were recovered in lavage fluid after intervals of 0.5, 1, 1.5, and 2 h. These levels did not differ statistically (p > 0.05). The amount of N-9 recovered dropped significantly at 4 h to 11.0 mg. If it is assumed that an N-9 concentration of 0.100 mg/mL is required to immobilize sperm in vitro, this study suggests that the amount of N-9 remaining in the vagina in the form of dissolved film up to 4 h after insertion of VCF is sufficient to immobilize sperm. The lavage procedure may not have recovered all N-9 remaining in the vagina. However, intercourse did not take place between insertion and lavage; if it had, the proportion of the film remaining undissolved and the total amount N-9 remaining in the vagina at the time of examination might have been affected.

Evaluation of polyacrylamide gel as substitute for human cervical mucus in the sperm penetration test

OBJECTIVE

To compare polyacrylamide gel as synthetic medium with human cervical mucus (CM) for the in vitro sperm-penetration test during infertility investigation.

PATIENTS

One hundred sixty-nine randomly chosen couples with a median duration of infertility of 4 (range, 1 to 16) years presenting at the infertility unit of the Women's University Hospital of Heidelberg, Germany.

MAIN OUTCOME MEASURES

Evaluation of sperm migration in polyacrylamide gel used in four different concentrations (1.5%, 1.6%, 1.7%, 1.8%) in the capillary tube test in parallel with CM of patients' female partners and CM of fertile donors, obtained under standardized conditions. Correlation of migration test results with outcome of semen analysis including microbial cultures and testing for local antisperm antibodies by means of the mixed antiglobulin reaction, postcoital testing, and the subsequent pregnancy rate after control for female infertility factors in a prospective study.

RESULTS

Sperm ability to penetrate the synthetic medium (concerning all concentrations) correlated significantly with the penetration of human CM, although polyacrylamide proved to be a stronger barrier. Sperm velocity and duration of progressive motility were markedly reduced in polyacrylamide. Polyacrylamide results correlated with the outcome of standard sperm analyses but not with sperm antibody testing. No clear differentiation was obtained with regard to subsequent fertility (19% after 6 months), although adequate sperm migration in polyacrylamide 1.8% was significantly more frequent in the fertile group.

CONCLUSIONS

In analyzing the intrinsic motility, penetration testing with polyacrylamide gel provides important information not obtained by routine sperm analysis. However, particularly with regard to immunological factors and fertility prognosis, human CM should be preferred whenever possible.

Clinical significance of crossed in vitro sperm-cervical mucus penetration test in infertility investigation

To evaluate the clinical significance of in vivo and in vitro testing of sperm ability to penetrate cervical mucus (CM), postcoital testing (PCT) and in vitro sperm-cervical mucus penetration testing were compared in a prospective study. Both in vivo and in vitro tests were standardized and performed after an oral course of estrogen therapy. Crossed in vitro sperm-cervical mucus penetration test, evaluated in 277 couples with CM of patients' wives and additionally with CM and semen of fertile donors, revealed that the male factor contributed to a significantly higher extent to deficient sperm-mucus interaction than the cervical factor. The overall pregnancy rate after 6 months was 23% (64/277). Whereas the outcome of PCT did not significantly predict subsequent fertility (PCT good pregnancy rate 24%/PCT poor 20%), significant differences were found for the sperm-cervical mucus penetration test with CM of patients' wives (pregnancy rate, 30.5% versus 8.5%) and for in vitro testing with donors' CM, but not for the mucus penetration test with donors' spermatozoa. Routine sperm analysis did not prove to be of prognostic value for a subsequent pregnancy. The results suggest that the in vitro sperm-cervical mucus penetration test is a good parameter of sperm function and, in particular, when performed as a cross-matching penetrability test, a valuable adjunct to PCT with regard to fertility prognosis.

Poissons, grenouilles, femmes et hommes: the appropriation and retention of archetypal systems for reproduction

In contradistinction to other biological systems, the reproductive mechanisms in sexually reproducing species are unique in that their success relies upon a synchronous interaction between two separate individuals. Reproduction has become increasingly more efficient as higher forms have developed internal fertilization and gestation. Although our anthropomorphic perspective has dominated the understanding of reproductive processes, 'recent discoveries' make it clear that this reproductive efficiency has been gained by retention of previously present biological mechanisms whose origins are in the vestigial excretory tracts and ducts which are the precursors of the reproductive tract. We refer to these as 'archetypal systems'. They include the interaction between sex steroid sensitive tissues and sex steroids, the renin-angiotensin system and the macrophage/monokine response to infection. Through these mechanisms the reproductive tracts have maintained control over the microenvironment in which the reproductive processes occur. Thus, gamete development in male and female, and fertilization and early embryonic existence in the female tract prior to implantation still occur in compartments which are extracorporeal, i.e., separated from blood or subendothelial spaces, and are controlled by cellular mechanisms found in ancient excretory tracts. Since the majority of the changes between lower forms and contemporary mammals are anatomical modifications which have favoured the success of these extracorporeal events within the developing, generally land-based mammals, we should take special note of lower animals, understanding the evolutionary appropriation of mechanisms designed to furnish the suitable microenvironment from the surrounding tissues.(ABSTRACT TRUNCATED AT 250 WORDS)

Correlation of human sperm motility characteristics with an in vitro cervical mucus penetration test

Semen analysis was performed on 226 ejaculates by an integrated microcomputerized system employing the multiple-exposure photography (MEP) method. Mucus penetration tests were performed in vitro using commercial preparations of bovine cervical mucus. A highly significant (P less than 0.001) correlation between mucus penetration distance and sperm count (r = 0.582), motility (r = 0.357), velocity (r = 0.569), motile density (r = 0.582), motility index (r = 0.467), and morphology (r = 0.383) was observed. Increased percentages of immature germ cells (r = -0.318) and bent-tailed sperm (r = -0.221) were the most strongly correlated with mucus penetration. Approximately 10% to 15% of patients with otherwise normal semen parameters displayed poor penetration of mucus. Conversely, 5% to 40% of patients with abnormal semen parameters displayed excellent penetration of the mucus. Motile density and velocity demonstrated the strongest relationship with the outcome of the mucus penetration test. These results suggest that a significant subpopulation of patients can be identified as having inadequate (or adequate) penetration of mucus with otherwise normal (or abnormal) motility characteristics.

A comparison of the bovine cervical mucus penetration test and the postcoital test

In 68 ejaculates an in vitro bovine cervical mucus penetration-test (Penetrak) was compared to the postcoital-test and the spermiogram. There was a positive correlation between the Penetrak-Test and concentration, motility, and morphology of the spermatozoa, however there was no correlation to the postcoital test. In connection with the PCT, the bovine mucus penetration-test seems to be a useful tool in the exploration of male infertility.

Application of a bovine cervical mucus penetration test

One hundred seventy-eight ejaculates obtained from infertility patients were evaluated by routine semen analysis and by a bovine cervical mucus penetration test (BCMPT). A significant correlation (p less than 0.01) was observed between mucus penetration and both sperm count (r = 0.349) and sperm motility (r = 0.394). One hundred fifty-two of 178 patients (85%) had normal sperm counts (greater than 20 x 10(6)/ml). Of these patients, 68% had good (greater than 30 mm), 26% had questionable (21-30 mm), and 7% had abnormal (less than 20 mm) penetration values. One hundred sixty-one of 178 patients (90%) had normal sperm motilities (greater than 40%). Of these patients, 71% had good, 25% had questionable, and 4% had abnormal penetration values. Conversely, 46% and 18% of patients with abnormal sperm count and motility, respectively, had normal penetration values (greater than 30 mm). A significant relationship (p less than 0.05) was observed between the BCMPT and pregnancy problems not apparent by semen analysis data, and may prove to be a useful adjunct to the use of routine semen analysis in evaluating male fertility.

Concentrations and composition of glycosaminoglycans in the female bovine reproductive tract

Our objective was to isolate glycosaminoglycans from various regions of the female bovine reproductive tract to ascertain their concentrations and composition. Oviducts, uterine horns, and cervices from 104 female bovine reproductive tracts obtained at slaughter were flushed with 5 ml phosphate buffered saline. Following proteolysis, glycosaminoglycans were isolated by alcoholic precipitation, and concentrations were quantitated by high performance liquid chromatography. Concentrations of glycosaminoglycans decreased significantly anterior to the cervix. There was an increase of chondroitin sulfates and heparin-like material in estrual cervical mucus compared with cervical mucus collected during the luteal phase of the estrous cycle.

Scanning electron-microscopic study of sperm retention and migration in the vagino-cervical region of the rabbit

The pattern of sperm retention and migration in the vagino-cervical region of rabbit was studied by means of scanning electron microscopy. The following phenomena were observed: 1) Spermatozoa located in the vagina and at the orifice of the ectocervix are usually distributed diffusely. They appear to be resting on the epithelial surface; many are structurally abnormal or decapitated. 2) The great majority of spermatozoa, however, seems to be anchored or retained in narrow epithelial channels with their heads in close file formations. This phenomenon was observed particularly in the fornix vaginae as late as 24 h post coitum. 3) A great number of spermatozoa invading the cervix evidently migrates in groups along the mucosal surface. Their heads are oriented toward the uterus and contact the epithelial cells. Spermatozoa that migrate beyond the cervico-uterine junction are distributed in the same manner. 4) Spermatozoa colonizing the cervical crypts appear to be attached via the anterior margins of their heads to the epithelial cells or to the tips of kinocilia. Their tails project into the crypt lumen. It is suggested that mainly three factors may be responsible for these phenomena: (i) the fact that only motile spermatozoa overcome the vagino-cervical barrier; (ii) the tendency of spermatozoa to move along the mucosa in close vicinity to the epithelial cells; and (iii) the inability to recognize mechanical barriers on the migration route (e.g., cervical crypts) and to overcome them quickly. This may be one of many possible causes leading to sperm retention in the vagino-cervical region.

Studies on bonnet monkey cervical mucus. The effect of proteases on mucus glycoproteins of Macaca radiata

The influence of proteinases on monkey cervical glycoproteins was investigated to assess their effect on cervical mucus and, thereby, on sperm penetration. The major component of periovulatory cervical mucus, a high molecular weight glycoprotein, was treated with Pronase, trypsin, chymotrypsin, papain, and bovine seminal peptidase, and the enzyme-resistant glycoprotein was purified by gel filtration on Sepharose 2B. A macromolecular component in high yield was recovered containing carbohydrate and protein moieties. Asialoglycoprotein, on treatment with Pronase, trypsin, and bovine seminal peptidase released more than one glycoprotein fragment. The carbohydrate and amino acid components of the native and degraded glycoproteins were similar in composition with variations in proportions. The structure of the carbohydrate-rich, pronase-resistant glycoprotein, further purified on Sepharose 2B, was examined. Sequential Smith degradation and methylation of the degraded glycoprotein fragment established a structure that shows some differences to that of the native glycoprotein. The influence of proteinases on cervical-mucus glycoproteins and a possible mechanism of sperm penetration through Pronase-treated glycoproteins is discussed.

Human cervical mucus. IV. Viscoelasticity and sperm penetrability during the ovulatory menstrual cycle

Quantitative viscoelastic and sperm penetration measurements were made on individual human cervial mucus samples collected from several ovulatory menstrual cycles. An inverse relationship was found to exist between these two mucus properties, with peak penetrability seen during the ovulatory phase of the cycle when viscoelasticity was lowest. Limited sperm penetration was also observed with follicular phase mucus. When mucus was collected three times daily, the first sample of the day showed reduced pH values and elevated percentage of nondialyzable solids (NDS) and viscoelastcity. Rates of mucus production were calculated for two cycles; the highest rate was seen during the ovulatory phase, with the follicular and luteal phases showing approximately 50% and 30% of this rate, respectively. Limited disparities were noted between midcycle changes in percentage of mucus NDS and viscoelasticity and in blood levels of total estrogens.

Morphology of postcoital spermatozoa in the cervical secretion and its clinical significance

Morphologic analysis of spermatozoa recovered 10 hours postcoitally from the human female genital tract and its correlation to the clinical situation have shown that (1) spermatozoa in the vagina are equivalent to those in the semen sample; (2) spermatozoa within the cervical secretion exhibit significantly better morphology than do those of the semen sample, indicating the presence of a barrier against abnormal spermatozoa at the level of the external os; (3) this barrier is significantly more effective in cases where conceptions later occur than in cases of persistent, unexplained infertility; and (4) the barrier is particularly active against spermatozoa with abnormal heads.

A new method for evaluating cervical penetrability using daily aspirated and stored cervical mucus

Cervical mucus samples from 33 women undergoing fertility work-up and married to normospermic husbands were aspirated daily with a tuberculin syringe during the periovulatory period. Samples were transferred to polyethylene tubing, sealed, and stored at 4 degrees C for 7 to 14 days. In vitro sperm penetration tests were performed in each case, using only one sample of husband's semen with all of the mucus samples that were collected during one cycle. Preliminary studies with 50 samples of cervical mucus taken at random showed that no difference in physicochemical and penetrability properties existed between fresh mucus and mucus stored for 10 to 14 days. Very often the optimal penetrability of the cervical mucus occurred on unpredictable days. In contrast, many tests performed on days which would have been predetermined for in vivo postocital tests were poor; consequently, those in vivo tests would have been falsely interpreted as negative. This new test using daily aspirated and stored mucus, which is simple to perform, is valuable mainly because it may eliminate the false negative results of other penetration tests. In this way the diagnosis of a truly hostile cervix may be more accurate.

The temperature, pH, and partial pressure of oxygen in the cervix and uterus of women and uterus of rats during the cycle

Changes in the temperature, pH, and partial pressure of oxygen (PO2) in the cervical canal and cavum uteri were measured in women with or without an intrauterine device and in the uteri of rats throughout the cycle. Only the PO2 exhibited significant variations, rising during the ovulatory phase in both cervices of women and uteri in rats. It is speculated that the rise in PO2 is related to the function of these organs as reservoirs for spermatozoa.