The uterine cervix in mammals

Transcervical uterine flushing and embryo transfer in sheep: Morphophysiological basis for approaches currently used, major challenges, potential improvements, and new directions (alas, including some old ideas)

At present, the success of non-surgical embryo recovery (NSER) and transfer (NSET) hinges upon the cervical passage of catheters, but penetration of the uterine cervix in ewes is problematic due to its anatomical structure (i.e., long and narrow cervical lumen with misaligned folds and rings). It is a major obstacle limiting the widespread application of NSER and NSET in sheep. While initial attempts to traverse the uterine cervix focused on adapting or re-designing insemination catheters, more recent studies demonstrated that cervical relaxation protocols were instrumental for transcervical penetration in the ewe. An application of such protocols more than tripled cervical penetration rates (currently at 90-95 %) in sheep of different breeds (e.g., Dorper, Lacaune, Santa Inês, crossbred, and indigenous Brazilian breeds) and ages/parity. There is now sufficient evidence to suggest that even repeatedly performed cervical passages do not adversely affect overall health and reproductive function of ewes. Despite these improvements, appropriate selection of donors and recipients remains one of the most important requirements for maintaining high success rates of NSER and NSET, respectively. Non-surgical ovine embryo recovery has gradually become a commercially viable method as even though the procedure still cannot be performed by untrained individuals, it is inexpensive, yields satisfactory results, and complies with current public expectations of animal welfare standards. This article reviews critical morphophysiological aspects of transcervical embryo flushing and transfer, and the prospect of both techniques to replace surgical methods for multiple ovulation and embryo transfer (MOET) programs in sheep. We have also discussed some potential pharmacological and technical developments in the field of non-invasive embryo recovery and deposition.

Optimizing ethyl cellulose-ethanol delivery towards enabling ablation of cervical dysplasia

In low-income countries, up to 80% of women diagnosed with cervical dysplasia do not return for follow-up care, primarily due to treatment being inaccessible. Here, we describe development of a low-cost, portable treatment suitable for such settings. It is based on injection of ethyl cellulose (EC)-ethanol to ablate the transformation zone around the os, the site most impacted by dysplasia. EC is a polymer that sequesters the ethanol within a prescribed volume when injected into tissue, and this is modulated by the injected volume and delivery parameters (needle gauge, bevel orientation, insertion rate, depth, and infusion rate). Salient injection-based delivery parameters were varied in excised swine cervices. The resulting injection distribution volume was imaged with a wide-field fluorescence imaging device or computed tomography. A 27G needle and insertion rate of 10 mm/s achieved the desired insertion depth in tissue. Orienting the needle bevel towards the outer edge of the cervix and keeping infusion volumes ≤ 500 µL minimized leakage into off-target tissue. These results guided development of a custom hand-held injector, which was used to locate and ablate the upper quadrant of a swine cervix in vivo with no adverse events or changes in host temperature or heart rate. After 24 h, a distinct region of necrosis was detected that covered a majority (> 75%) of the upper quadrant of the cervix, indicating four injections could effectively cover the full cervix. The work here informs follow up large animal in vivo studies, e.g. in swine, to further assess safety and efficacy of EC-ethanol ablation in the cervix.

Investigation of vaginal mucus parameters: Development of models for staging the oestrous cycle of the Bunaji cow

Changes in some vaginal mucus parameters were studied in order to generate predictive models capable of enhancing oestrous cycle staging, using equal groups (unsynchronized-USC [no treatment] and synchronized-SC [Synchromate^® i/m on d0, d11]) of Bunaji cows (n = 48) aged 3-4 years. Vaginal mucus was collected (starting d11 in SC) daily over 26 days using standard procedures. Physical (viscosity, elasticity, density, resistivity) and biochemical (pH, glucose, cholesterol, total protein, calcium, magnesium, sodium, potassium) parameters were evaluated using standard procedures. Data were analysed using chi-square and multinomial logit regression modelling. Models generated using oestrus as reference categories were ascertained for accuracies. Chi-square values for viscosity, elasticity and density were significant (p < .01) in USC and SC across stages of the cycle. Results for USC showed that pH and cholesterol were predictive (p < .01) for pro-oestrus, metoestrus and dioestrus, while total protein was predictive (p < .01) for dioestrus only. Similarly, magnesium was predictive (p < .05) for pro-oestrus. For SC, pH, magnesium and cholesterol were predictive (p < .01) for pro-oestrus, metoestrus and dioestrus, while total protein was predictive (p < .01) for pro-oestrus and dioestrus. Potassium and total protein were also predictive for metoestrus at 10% and 5% significance levels, respectively. Though findings suggest the usefulness of magnesium in staging the oestrous cycle only in synchronized cows, pH, total protein and cholesterol appeared to be the more important vaginal mucus parameters in Bunaji cows, regardless synchronization. Furthermore, the models developed showed high accuracy levels for staging the oestrous cycle in USC (100%) and SC (89%).

Morphological changes in the porcine cervix: A comparison between nulliparous and multiparous sows with regard to post-cervical artificial insemination

In recent decades, new artificial insemination (AI) methods, such as post-cervical AI (PCAI), have been developed in pig. PCAI involves crossing the cervix to deposit the sperm in the uterine body. Although PCAI application in sows is frequent, its application in nulliparous (gilts) females it is still limited due to the difficulty of passing through the cranial part of the cervical lumen. We hypothesized that ageing and parity would modify the cervical canal, facilitating the introduction of AI devices through the cervix. The aim was to compare the morphology of the uterus at different levels between multiparous and nulliparous females. Morphological analysis of the uterus pointed to a longer cervix (25.9 ± 4.6 vs. 21.6 ± 3.3 cm, p < 0.001) and greater length of the part of the reproductive tract involved in PCAI (from rima vulvae to the last cervical cushion) (56.2 ± 6.0 vs. 50.3 ± 5.2 cm, p < 0.001) in multiparous sows compared with nulliparous animals. As regards the structure of the vaginal and uterine parts of the cervix (the part in contact with the vagina and uterine body, respectively), the cross-sectional area, perimeter and total thickness were greater in the uterine part of multiparous than of nulliparous animals (area: 4.07 ± 1.46 vs. 2.46 ± 0.56 cm², p < 0.01; perimeter: 8.50 ± 1.44 cm vs. 6.28 ± 0.92 cm, p < 0.001; thickness: 10.79 ± 0.96 vs. 8.35 ± 0.62 mm, p < 0.05), but not in the vaginal part. The tissue content analysed in histological cross-sections also showed differences between female groups, a greater content of connective tissue (58.86 ± 10.78 vs. 67.60 ± 13.38%, p < 0.001) and a lower amount of muscle fibres (39.79 ± 10.24 vs. 30.66 ± 13.69%, p < 0.001) being observed in multiparous sows. Finally, silicone casts of the cervical lumen revealed differences between the two groups in the size and shape of the ridges in the lumen trajectory. Parity, which is also influenced by ageing, determines important changes in the size, structure and tissue content of the cervix wall, as well as in the morphology of the cervical canal, which may be responsible for the different levels of performance of PCAI in the female populations. Therefore, the future design of AI strategies and catheters should take into consideration the morphological variations of the cervix lumen, which will depend on age and parity of the females.

The evolution of genital shape variation in female cetaceans

Male genital diversification is likely the result of sexual selection. Female genital diversification may also result from sexual selection, although it is less well studied and understood. Female genitalia are complex among whales, dolphins, and porpoises, especially compared to other vertebrates. The evolutionary factors affecting the diversity of vaginal complexity could include ontogeny, allometry, phylogeny, sexual selection, and natural selection. We quantified shape variation in female genitalia using 2D geometric morphometric analysis, and validated the application of this method to study soft tissues. We explored patterns of variation in the shape of the cervix and vagina of 24 cetacean species (n = 61 specimens), and found that genital shape varies primarily in the relative vaginal length and overall aspect ratio of the reproductive tract. Extensive genital shape variation was partly explained by ontogenetic changes and evolutionary allometry among sexually mature cetaceans, whereas phylogenetic signal, relative testis size, and neonate size were not significantly associated with genital shape. Female genital shape is diverse and evolves rapidly even among closely related species, consistent with predictions of sexual selection models and with findings in invertebrate and vertebrate taxa. Future research exploring genital shape variation in 3D will offer new insights into evolutionary mechanisms because internal vaginal structures are variable and can form complex spirals.

Characterization of the cervical mucus plug in mares

The cervical mucus plug (CMP) is believed to play an integral role in the maintenance of pregnancy in the mare, primarily by inhibiting microbial entry. Unfortunately, very little is known about its composition or origin. To determine the proteomic composition of the CMP, we collected CMPs from mares (n = 4) at 9 months of gestation, and proteins were subsequently analyzed by nano-LC–MS/MS. Results were searched against EquCab2.0, and proteomic pathways were predicted by Ingenuity Pathway Analysis. Histologic sections of the CMP were stained with H&E and PAS. To identify the origin of highly abundant proteins in the CMP, we performed qPCR on endometrial and cervical mucosal mRNA from mares in estrus, diestrus as well as mares at 4 and 10 m gestation on transcripts for lactotransferrin, uterine serpin 14, uteroglobin, uteroferrin, deleted in malignant brain tumors 1 and mucins 4, 5b and 6. Overall, we demonstrated that the CMP is composed of a complex milieu of proteins during late gestation, many of which play an important role in immune function. Proteins traditionally considered to be endometrial proteins were found to be produced by the cervical mucosa suggesting that the primary source of the CMP is the cervical mucosa itself. In summary, composition of the equine CMP is specifically regulated not only during pregnancy but also throughout the estrous cycle. The structural and compositional changes serve to provide both a structural barrier as well as a physiological barrier during pregnancy to prevent infection of the fetus and fetal membranes.

A comparison between cervical dimensions of pregnant and nonpregnant Santa Gertrudis and Bos taurus cows

Cervical measurements were recorded on palpation per rectum for 603 Bos taurus , Santa Gertrudis, and crossbred cattle. Postmortem cervical measurements were recorded for 77 of these cows. Antemortem measurements were positively correlated with those taken at postmortem examination (cervical diameter: r=0.75, P<0.01 and cervical length: r=0.29, P<0.06). Cervical diameters from antemortem and postmortem specimens were greater in Santa Gertrudis cattle than in Bos taurus and crossbred cattle (P<0.05). Cervical shape was different between Santa Gertrudis cattle and Bos taurus or crossbred cattle (P<0.01), with Santa Gertrudis cows having a higher incidence of conical shaped cervices than other breeds. Within Santa Gertrudis cattle, the incidence of conical cervical shape increased with age (P<0.05). Conical cervical shape was associated with a lower pregnancy rate in all breeds (P<0.01). Within Santa Gertrudis cattle, conical cervical shape was associated with a lower pregnancy rate in 1- to 4-year-old cows (P<0.05) but not in cows more than 4 years of age (P>0.05).

Rheological properties of the anterior vaginal fluid from superovulated dairy heifers at estrus

Anterior vaginal fluid samples were collected from 25 dairy heifers induced to superovulation at 12 to 20 hours after estrus detection. Thixotropy and flow behavior were evaluated. In samples from 19 heifers, structural variation was registered and the fluids were considered to be thixotropic; in the remaining samples (6 heifers), structural variation was not registered and the fluids were considered to be nonthixotropic. The mean estradiol concentration of the thixotropic fluids (20.8 pg/ml) was lower (P=0.0002) than of the nonthixotropic samples (56.7 pg/ml). All the nonthixotropic samples of anterior vaginal fluid exhibited Newtonian behavior. Of the 25 thixotropic anterior vaginal fluid samples, 10 exhibited Newtonian behavior while 9 exhibited non-Newtonian behavior. Heifers in which samples exhibited Newtonian behavior had a higher mean estradiol concentration (38.8 pg/ml; P=0.003) than heifers in which samples exhibited non-Newtonian behavior (12.8 pg/ml). Estradiol concentrations were correlated negatively (P=0.02) with the index of consistency (r = -0.46) and were not related to structural variation (P=0.08), although a certain tendency was shown. These results have shown that thixotropic and flow behavior measurements in the anterior vaginal fluid of superovulated estrous heifers vary over a wide range and even qualitatively. This variation is related to estrogen levels: Fluidity increases with increased plasma estrogen values, and the integrity of the gel structure tends toward elimination.

Crystallisation pattern of vestibular mucus and its relation to vestibular electrical resistance in cycling sow

Changes in the genital mucus around the oestrus are used by different diagnostic methods to determine optimal fertilisation time. In the current study, the authors evaluated the different arborisation patterns found in vestibular mucus, and also established its relationship with vestibular resistance changes during oestrus. Thirty multiparous sows were checked by transrectal ultrasonography to determine ovulation time every 12 hours. Vestibular resistance was measured with a commercial resistance probe, and vestibular mucus ferning was also evaluated every 12 hours during the oestrus. Significant changes (P < 0.05) in vestibular resistance were detected, registering high variation among individuals. Maximum resistance data was reached between 12 and 24 hours after ovulation time in 83 per cent of the sows. Crystallisation samples were classified into three different patterns according to the fern-like crystal degree. Arborisation peak occurred from 48 to 36 hours before the moment of ovulation, when vestibular resistance values increased gradually. In the optimal insemination moment, vestibular resistance increased significantly (P < 0.05) and vestibular mucus showed a low crystallisation pattern (P < 0.05). Combining several methods to measure genital mucus changes may predict the ovulation time and the best insemination moment.

Ultrastructural and Rheological Properties of Bovine Vaginal Fluid and its Relation to Sperm Motility and Fertilization: a Review

The tubular genital organs of the mammalian female reproductive tract provide different luminal microenvironments that can act as an aid or a barrier to gamete transport and the first steps of embryonic development. The mechanism of sperm transport through the genital tract has not been fully established but, first of all, sperm cells encounter and need to overcome mucous-like secretions to reach the site where fertilization occurs. One of these secretions, vaginal fluid, is a complex biological product, which is mainly derived from cervical mucus. In this review, we focus on recent studies that describe the relationships between the ultrastructural and rheological properties of bovine vaginal fluid and sperm motion. In the light of this, we propose bovine vaginal fluid as a morphofunctional model for the study of sperm transport in mammals.

Cellular turnover in the rat uterine cervix and its relationship to estrogen and progesterone receptor dynamics

Histoarchitectural changes of the uterine cervix allow its successful adaptation to different physiological conditions. In this study, we evaluated cell turnover in each cellular compartment of the uterine cervix in association with steroid hormone receptor expression in order to establish the range of physiological changes. Proliferation, apoptosis, and progesterone receptor (PR) and estrogen receptor alpha (ERalpha) expression were evaluated in cycling, pregnant, and postpartum rats. In estrus and diestrus II, ERalpha and PR expression exhibited variations according to the region evaluated. Proliferation and apoptosis showed a reciprocal pattern, the epithelium being the region with higher cell turnover. High apoptotic index (AI) in estrus was associated with the lowest ERalpha and the highest PR scores. During pregnancy, proliferation of the epithelium was the predominant event and AI was low. On Postpartum Day 1 (PPD1), proliferation decreased while apoptosis increased. As described for the estrous cycle, during pregnancy and PPD1, AI and ERalpha were negatively correlated. In the fibroblastic stroma, low proliferation was observed throughout pregnancy; however, there was a net increase in cell number because very few cells underwent apoptosis. No difference in ERalpha was observed in fibroblastic cells during pregnancy and postpartum; however, a great decrease of this receptor in the epithelial compartment was observed after delivery. Unlike cervical epithelium, PR was highly expressed in stromal cells. At term, a dramatic increase in epithelial PR was observed. While epithelial PR remained high on PPD1, a decrease was observed in muscle stroma. These results show that, in all stages studied, 1) ERalpha and PR have different patterns of expression with differential responses to signals that modulate proliferation and/or apoptosis depending on the cellular compartment, and 2) even though the epithelium is the region with the highest cell turnover, the fibroblastic and muscle stroma are active regions that have their own patterns of behavior.

Rheological and ultrastructural properties of bovine vaginal fluid obtained at oestrus

The properties of cervical-vaginal fluid are under strict hormonal control: and in mammals in which semen is deposited in the anterior vagina, changes produced in these properties can result in a lower or higher resistance to sperm motion. The aim of this study was to determine whether the structural organization of bovine vaginal fluid is related to its rheological properties. Vaginal fluid samples were collected from 41 cows at oestrus: 20 at the middle of oestrus (between 8 and 12 h after starting) and 21 at the end of oestrus (between 18 and 22 h). Flow behaviour was determined using a viscosimeter, and the ultrastructural analysis was performed by scanning electron microscopy. Six samples showed newtonian behaviour: three collected at the middle and three collected at the end of oestrus. Newtonian samples had dense and compact matrices arranged as membranes with rough, irregular surfaces, and sparse, thin filaments (< 150 nm). Non-newtonian samples collected at the end of oestrus (n = 18) had a higher (P = 0.016) consistency index (K = 944 +/- 229 mPa.s(n)) than those collected at the middle of oestrus (n = 17; K = 237 +/- 84 mPa.s(n)). Thick filaments (> 700 nm) that were either randomly arranged with thinner filaments forming a mesh or heavily cross-linked by thin filaments (50-150 nm) were observed in all non-newtonian samples collected at the end of oestrus, while medium-diameter filaments (between 200 and 500 nm) forming loose networks were observed in non-newtonian samples collected at the middle of oestrus. These findings indicate a close relationship between the molecular organization of the structural elements of bovine vaginal fluid and its rheological behaviour. Vaginal fluid dramatically reduces its mechanical barrier effect during the course of oestrus but always appears to maintain its three-dimensional filamentous structure. The images of vaginal fluid showing newtonian behaviour would appear to support previous results, suggesting that this property may be related to bovine infertility.

A structural study of the bovine vaginal fluid at estrus

The present study describes the structural components of the bovine vaginal fluid at estrus by scanning electron microscopy (SEM) following critical point- and freeze-drying preparation procedures. Confocal scanning laser microscopy (CLSM) was also used to evaluate the structural integrity of samples, and a control sample was assessed by adding sperm to the vaginal fluid. Samples were collected from 10 cows at the time of artificial insemination, prepared for SEM by using critical point- and freeze-drying procedures, gold coated, and observed by SEM. Mesh size and filament thickness were measured with an image analyzer. Of the 10 samples processed, 4 were considered altered following critical point drying. Compaction and lack of filaments were observed in these samples. A small area of one sample showed a honey comb-like structure when freeze drying was used. Nonoriented filaments with different thicknesses and with a network-like structure were observed throughout the remainder of the samples. Filaments throughout all samples were also observed by CSLM. After critical point drying, the mesh area ranged from 0.8 to 101.4 microns 2; the minor axis from 0.7 to 10.8 microns; and filament thickness from 40 to 442 nm. Using freeze drying, the mesh area ranged from 0.9 to 493.8 microns 2; the minor axis from 0.7 to 27.5 microns; and filament thickness from 40 to 800 nm. When samples were freeze dried, mesh values were similar to the interstrand channels observed by CSLM. In sperm-vaginal fluid samples, following critical point- or freeze-drying procedures, spermatozoa were oriented randomly in the vaginal fluid and did not seem to alter filamentous structure. Our data suggest that the freeze-drying procedure better preserves the true structural dimensions of the vaginal fluid. Furthermore, the filamentous structure of the vaginal fluid does not appear to impede sperm transport.

A scanning electron microscope study of the structural component of the bovine vaginal fluid at oestrus

The ultrastructure of the vaginal fluid of cows at oestrus was analysed by scanning electron microscopy. Samples of vaginal fluid were collected from 7 normally cycling and healthy cows, 3 to 4 years of age, in oestrus. Evaluation of the patterns of crystallization was used as a previous assessment of the quality of the samples. SEM images revealed a structure made up of non-oriented filaments constituting a network with a three-dimensional arrangement. These filaments were of different diameters and ranged between 50 and 400 nm. Mesh size, defined as the minimum distance measurement between strands, ranged between 2 to 8 microns.

Relationship of sperm migration in anterior vaginal fluid and embryo quality in superovulated dairy heifers

Anterior vaginal fluid samples from 26 superovulated dairy heifers at insemination were classified into 2 grades: 1) with abnormal sperm penetration ability when vanguard sperm migration was randomly oriented; and 2) with normal sperm penetration ability when vanguard sperm migration was parallel and unidirectional. Vanguard sperm behavior and vanguard sperm migration distances were evaluated for their effects on fertilized ova recovery rates and transferable embryo recovery rates. Twelve vaginal fluid samples (46%) showed abnormal sperm penetration ability (Grade 1) and the mean +/- sem distance traveled by the vanguard spermatozoa into these samples (7.3 +/- 0.9 mm) was different (P<0.0001) from the remainder of the samples (48 +/- 3.4 mm) in which sperm penetration was registered as normal (Grade 2). In heifers in which anterior vaginal fluid samples were Grades 1 and 2, the fertilized ova recovery rates were 78.3% and 80.2%, respectively (P=0.91). Transferable embryo recovery rates were 54.2% and 32% for Grades 1 and 2, respectively (P<0.001). Using correlation and linear regression analysis, the sperm migration distance in Grade-2 samples was not related to fertilized ova (P=0.77) or to transferable embryo recovery rates (P=0.97). These results indicate that vanguard sperm movement into capillary tubes varied qualitatively and was related to subsequent embryo quality.

Postnatal development of the cervical epithelium in the Mongolian gerbil

This study analyzes the postnatal development of the Mongolian gerbil's cervical epithelium, in relation to its future functions. In the newborn gerbil the outline of the cervical canal is smooth, showing hardly any signs of folding. The epithelium consists of 1 to 3 layers. The cervical cells have rounded apices of regular outline and contain a large amount of glycogen. The first secretory products of specific mucus type appear about day 23 postnatally (p.n.). Initially two types of vesicles can be identified, as compared with only one type in sexually mature animals. The process of mucification begins in the vagina and the external os of the cervix and spreads towards the cervical horns. The cervical canal, besides growing longer, becomes increasingly folded during development. At about day 50 p.n., with the onset of sexual maturity, an upper endocervix and a lower ectocervix can be distinguished within the cervical canal. In the fully mature animal, the endocervix consists of 4 to 5 layers, in which apical cells mucify and exfoliate. In the ectocervix, the epithelium can be divided into 4 to 5 basal layers and 5 to 7 upper layers which mucify, keratinize, and exfoliate, according to the cyclic phases of the vagina. Diapedesis of leucocytes through the epithelium starts around day 45 p.n.

Light and electron microscopic observation on the cervical epithelium of the rabbit. I

The light and electron microscopy of the cervical epithelium of ovulatory, estrous, and long-term ovariectomized rabbits have been studied to determine what structural changes occur under different hormonal conditions. The percentage of nonciliated secretory cells is 49.6 in ovulatory, 43.6 in estrous, and 23.7 in long-term ovariectomized rabbits, and of ciliated cells is 50.2 in ovulatory, 56.2 in estrous, and 76.3 in long-term ovariectomized animals. The values for the ovulatory and estrous rabbits are significantly different at the P less than 0.05 level from those of the ovariectomized animals. In all 3 groups the general ultrastructure of the normal ciliated cells is similar. Interestingly, the Golgi complex is very prominent in all. Glycogen bodies occur frequently only in ciliated cells of ovariectomized and occasionally of estrous animals. Abnormalities in ciliation are quite common in the ovariectomized rabbits. The structure of the nonciliated secretory cells varies appreciably within and between the 3 groups. In these cells from well-developed epithelia of certain ovulatory and estrous animals, the apical cytoplasm contains secretory granules of at least three types. In addition, very irregularly shaped, dense, perinuclear granules occur, which may be another type of secretory granule or lysosomes. As compared to ciliated cells, the secretory cells have less prominent Golgi complexes, more abundant bundles of intermediate filaments, a more extensive glycocalyx on their apical surface, and more heterochromatic nuclei. In comparison to the cells of well-developed epithelia, the nonciliated cells of some other ovulatory and estrous rabbits are less well differentiated with fewer or no secretory granules and less well developed organelles. In the nonciliated cells of the long-term ovariectomized rabbits, there are no secretory or dense perinuclear granules. There is a decrease in the number of organelles that are involved in secretion, in the size of the cells, and in the amount of nuclear euchromatin.

Cholinergic and adrenergic neural control of smooth muscle function in the non-pregnant rat uterine cervix

The isolated circular smooth muscle of the uterine cervix from spayed rats was investigated in vitro. One group of animals was treated with oestrogen. Preparations from these rats showed no spontaneous contractile activity, but responded with contractions to electrical field stimulation. The contractions were blocked by approximately 85% with atropine, scopolamine and tetrodotoxin, but were unaffected by the adrenergic antagonists propranolol, phenoxybenzamine, and yohimbine. This neurogenic effect was potentiated by neostigmine. Noradrenaline inhibited the nerve-induced contractions and also lowered resting tension in a concentration-dependent way. The latter effect of noradrenaline was inhibited by propranolol. The indirect effects of noradrenaline on the electrically induced contractions were also inhibited by propranolol, but potentiated with phenoxybenzamine and, to a less extent, yohimbine. Nerve-induced relaxation was never observed. Acetylcholine contracted the smooth muscle by an effect that was counteracted by atropine. A second group of spayed rats was not given any steroid treatment. The cervix preparations from these animals showed spontaneous activity, which was uninfluenced by atropine, propranolol, phenoxybenzamine, yohimbine, and tetrodotoxin. Noradrenaline inhibited the spontaneous activity. This noradrenergic effect was counteracted by propranolol and potentiated by phenobenzamine. Acetylcholine increased the smooth-muscle tone by an atropine-sensitive action. The results suggest the presence of a cholinergic motor innervation on the non-pregnant rat uterine cervix. The cervix also receives an adrenergic innervation, which may act both post-junctionally (lowering resting tension and inhibiting spontaneous activity) and prejunctionally (modulating the cholinergic nerves) via beta-adrenergic as well as alpha-adrenergic receptors.

Filtering capacity of bovine cervical mucus towards abnormal forms of human-ejaculated spermatozoa

The filtration capacity of bovine cervical mucus (BCM), fresh bovine cervical mucus (FBCM) or frozen and thawed bovine mucus (BCMF) was studied, using human-ejaculated spermatozoa in comparison with the properties of human cervical mucus (HCM). Thirty semen specimens of good quality were used in cervical mucus (CM) penetrations, using capillary tubes containing CM of 30 HCM, 77 FBCM and 77 BCMF samples. Spermiocytograms were carried out on semen and cervical mucus at 1st and 3rd centimeter of the capillary tube after one hour of incubation. Smears were stained by Papanicolaou and the patterns of seven forms of sperm cells (normal, tapering, macrocephals, microcephals, pinhead, neck pathology and amorphous cells) were counted on a total of 100 cells in each slide. A clear, highly significant (P less than 0.0001) selection of cells penetrating the CM has been shown, preventing certain abnormal forms from penetrating the CM (macrocephals, neck pathology and amorphous cells) and enabling good penetration of normal sperm forms and moderate penetration of tapering, microcephals and pinhead cells. On the average, a specimen with normal sperm forms of 72% showed a spermiocytogram of 90% normal forms at the 3rd centimeter of migration. The same patterns of filtration were recorded in all the three sources of CM. It is suggested that BCM be used as a filter towards abnormal sperm forms in a highly teratozoospermic ejaculate in order to improve its quality for artificial inseminations.

Penetration of human ejaculated spermatozoa into human and bovine cervical mucus. I. Correlation between penetration values

Midcycle bovine cervical mucus (BCM), fresh (FBCM) or frozen at -20 degrees C (BCMF), and human cervical mucus (HCM) were collected and tested in in vitro penetration tests, using human ejaculated spermatozoa of good quality. Penetration tests were performed at 34 degrees C for 1 hour, and the penetration value (PV) was calculated. Duplicates of each run were in a narrow deviation. Correlations between PV rates of the same semen samples in the 3 sources were found to be significantly high (HCM versus FBCM, r = 0.958; HCM versus BCMF, r = 0.982, and FBCM versus BCMF, r = 0.985), suggesting that human ejaculated spermatozoa penetrate the cervical mucus of all three sources at the same rate.

Cyclic changes in the surface structure of the cervix from the ewe as revealed by scanning electron microscopy

Thirty parous ewes were divided into six groups and sacrificed on day 0 (first day of estrus), 1, 2, 10, 15 or 16 of the estrous cycle. The cervices were removed immediately and processed for examination with the scanning electron microscope. Observation of the tissues reveals that the surface of the cervix is highly convoluted, which results in the formation of numerous folds or crypts. Two forms of columnar epithelial cells, a ciliated and a non-ciliated cell with microvilli, line the luminal surface of the cerix in the day 10, luteal-phase ewes. However, on day 15, 2 days before estrus, the non-ciliated cells differentiate into two morphologically distinct types of secretory cells. One type forms when the apex of the non-ciliated cell dilates outward into the lumen of the cervix. Concurrent with apical enlargement, the microvilli are lost and the limiting cell membrane becomes smooth. The other type of cell is characterized by only a slight apical swelling. Consequently, remnants of microvilli along with secretory granules can be observed on the limiting membrane of this cell. Both cells release a particulate component, which is believed to be a precursor of mucus, into the lumen of the cerix. These particles undergo a series of morphological transformations to form a fibrillar layer, generally referred to as 'cervical mucus', that covers the epithelial surface at estrus. One to 2 days following the onset of estrus, the fibers become more closely assoicated with amorphous material that begins to coagulate, thereby revealing the underlying ciliated and non-ciliated cells that characterize the cervix of the luteal-phage ewe. The cyclical variation in secretory cells and factors that may influence that structural transformations which occur in mucus are discussed.

Mechanical responses of the isolated cervix and uterine horn of pregnant rats near term to drugs

1 The responses of circularly cut strips of cervix and uterine horn from rats on days 20 and 22 of pregnancy to drugs were compared in vitro. 2 The cervix exhibited similar responses and sensitivities to acetylcholine, bradykinin, prostaglandin (PG) F2alpha (day 20) and isoprenaline (day 20) as did the uterine horn but was less sensitive or responded less consistently to isoprenaline (day 22), oxytocin and PG1. PGE2 was more potent on the cervix (day 20). 3 Before term the relatively inextensible connective tissue of the cervix plus contractions of the smooth muscle would help to prevent foetal expulsion. At term the cervical smooth muscle is sufficiently unresponsive to allow cervical dilatation.