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Topic:Endometrium
The equine endometrium is the innermost lining of the uterus in horses, playing a vital role in reproductive health and fertility. It is responsible for providing a suitable environment for embryo development and implantation. The endometrium undergoes cyclical changes during the mare's estrous cycle, influenced by hormonal fluctuations. These changes prepare the uterus for potential pregnancy and are essential for maintaining uterine health. Various conditions, such as endometritis or endometrial fibrosis, can affect the endometrium, impacting reproductive efficiency. This page gathers peer-reviewed research studies and scholarly articles that explore the structure, function, and pathological conditions of the equine endometrium, as well as their implications for equine reproduction.
An immunohistological study of MHC class II expression and T lymphocytes in the endometrium of the mare. The distribution of T lymphocytes and of cells bearing MHC Class II antigens in the endometrium of the mare was studied using an avidin-biotin-peroxidase staining method. The cells within the endometrium which expressed MHC Class II were macrophages, lymphocytes, monocytes, dendritic cells, epithelial cells and endothelial cells. MHC Class II expression increased significantly (P < 0.05) in the luminal epithelium and tended (P = 0.0573) to increase in the subepithelial layers during oestrus. Numbers of T lymphocytes did not differ between oestrus and dioestrus. MHC Class II expression and T...
Effect of surgical removal of endometrial cups on concentrations of chorionic gonadotrophin and subsequent fertility in the mare. Seven pregnant mares underwent general anaesthesia, laparotomy, hysterotomy and removal of a 50-day conceptus. Eversion of the uterine horn through the hysterotomy site allowed direct visualisation and electrosurgical removal of endometrial cup tissue from 5 randomly selected mares (Nos 1-5), while cup tissue in 2 mares (Nos 6 and 7) was left intact. Two pregnant mares served as unoperated controls (Nos 8 and 9). Efforts to re-establish pregnancy were initiated 20 days after surgery. Serum samples collected before surgery and during the post-operative period were analysed for concentration of ...
Evaluation of progesterone treatment to create a model for equine endometritis. To investigate a model for equine endometritis, 12 mares with normal reproductive tracts were divided into 2 groups. All mares received progesterone in oil, 250 mg im, daily. At 5 days after initiation of progesterone administration, the uteri were inoculated with 10(6) colony forming units of Pseudomonas aeruginosa. The day of inoculation was designated Day 0. On Day 6, endometrial swab samples yielded P. aeruginosa in 5 mares; samples from the other 7 mares yielded heavy growth of Escherichia coli, Streptococcus zooepidemicus, Klebsiella pneumoniae, Enterobacter spp., Citrobacter diversus, S...
Pharmacokinetics of metronidazole and its concentration in body fluids and endometrial tissues of mares. Serum concentrations of metronidazole were determined in 6 healthy adult mares after a single IV injection of metronidazole (15 mg/kg of body weight). The mean elimination rate (K) was 0.23 h-1, and the mean elimination half-life (t1/2) was 3.1 hours. The apparent volume of distribution at steady state was 0.69 L/kg, and the clearance was 168 ml/h/kg. Each mare was then given a loading dose (15 mg/kg) of metronidazole at time 0, followed by 4 maintenance doses (7.5 mg/kg, q 6 h) by nasogastric tube. Metronidazole concentrations were measured in serial samples of serum, synovia, peritoneal flui...
Streptomycin-resistant Escherichia coli as a marker of vulvovestibular contamination of endometrial culture swabs in the mare. To investigate the vulvovestibular contamination of endometrial culture swabs in the mare, a liquid culture of a streptomycin-resistant strain of Escherichia coli was applied to the vulvovestibular area of mares and used as a marker of contamination of endometrial culture swabs. Prior to taking endometrial swabs, the perineal area was washed with soap, rinsed with water, and dried. Endometrial culture swabs were taken from mares that were in anestrus or diestrus and from mares that were in estrus. When a manual transvaginal swabbing technique was used, 22 of 24 endometrial swab specimens from ...
Effect of repeated collection of multiple endometrial biopsy specimens on subsequent pregnancy in mares. Endometrial biopsy specimens (4 or 5 on each occasion) were collected from 7 mares 2, 3, or 4 times over a 50-day period prior to breeding. Four of the collection days were within 6 days of breeding. Six of the 7 mares were diagnosed as pregnant by use of ultrasonography at day 14 after ovulation. This pregnancy rate was the same as that achieved by these mares when they were bred at estrus before the start of the study. It appeared that repeated collection of multiple endometrial biopsy specimens from genitally normal mares did not adversely affect pregnancy rate.
Plasma concentrations of 13,14-dihydro-15-ketoprostaglandin F2 alpha in mares during uterine involution. Twelve mares were allowed to foal naturally, after which they were monitored to study uterine involution. Starting on day 3 after parturition, the internal genital tract was examined per rectum manually and ultrasonographically every other day for changes in uterine characteristics and ovarian activity. By day 5, gravid and nongravid uterine horns were similar in size, and by day 7, uterine fluid was absent. On day 7 after parturition, endometrial biopsy samples were obtained for histologic evaluation, and uterine swab specimens were obtained for microbiologic culture. Uterine swab specimens f...
Videoendoscopic evaluation of the mare’s uterus: I. Findings in normal fertile mares. The new generation of videoendoscopes uses an electronic, instead of an optical, system for image transmission. Advantages over conventional fibre-optic endoscopes include increased image quality, handling robustness and direct display of the image on a TV monitor for multiple simultaneous viewing. In the present study, hysteroscopy was performed on 14 normal fertile Welsh Pony and Thoroughbred mares at various times during the annual and ovarian breeding cycles. Oestrus was characterised by an oedematous, relaxed cervix lying on the floor of the vagina, diffuse oedema of the endometrium and t...
Videoendoscopic evaluation of the mare’s uterus: II. Findings in subfertile mares. Videoendoscopy of the reproductive tract was performed in 87 Thoroughbred mares with histories of reduced fertility. During hysteroscopy samples for cytological, microbiological and histological examinations were obtained under visual control. Common findings in these broodmares included: (a) endometrial degeneration, as assessed by an uneven distribution or atrophy of endometrial folds and/or a scarred appearance of the endometrium (49 mares, 56%); (b) endometrial cysts of various sizes and locations within the uterus with the most common location being at the base of the uterine horns (48 ma...
Relationships of age to uterine function and reproductive efficiency in mares. The uterine function and reproductive efficiency of 31 nonlactating pony mares were compared for two age groups: young (5 to 7 years, n=9) and old (>/=15 years, n=22). For pregnant mares, differences between age groups were not significant for the diameter of the largest follicle, cross-sectional area of the corpus luteum, growth profile of the embryonic vesicle or embryo mobility characteristics. Uterine contractility scores were lower (P<0.05), day of fixation of the embryonic vesicle was later (P<0.05), and uterine tone tended (P<0.10) to be lower in the old than the young mares...
Comparison of endometrium before and after repair of third-degree rectovestibular lacerations in mares. The endometrial response of mares to repair of third-degree rectovestibular lacerations was evaluated. Endometrial biopsy specimens from 8 mares with third-degree rectovestibular laceration were obtained immediately before surgery and from 9 to 15 days after repair. Presurgical endometrial biopsy specimens were classified as category I for 2 mares; category II, attributable to slight endometritis, for 5 mares; and category III, attributable to moderate-to-severe endometritis, for 1 mare. Within 15 days after rectovestibular repair, all endometrial biopsy specimens were classified as category I...
Isolation and culture of glandular epithelial and stromal cells from the endometrium of mares. Glandular epithelial and stromal cells were isolated from the endometrium of mares by collagenase digestion and were incubated on plastic for 7-9 days until the cells formed confluent monolayers. The cells differed in morphology: epithelial cells appeared polyhedral and stromal cells were spindle like. The monolayers were incubated in the presence and absence of oxytocin. Medium was removed from wells after 2, 8 and 24 h of incubation. Concentrations of prostaglandin F (PGF) in the medium increased significantly during this time. Glandular epithelial cells produced significantly more PGF than ...
Early foetal death in the mare. Histological, bacteriological and cytological findings in the endometrium. Fifteen mares which had each lost their pregnancies 2 to 8 times during the preceding 6 years were used in a study comprising 1 or 2 breeding seasons for each mare. During the research period all 15 mares conceived and 10 of the mares had normal pregnancies in the 1st experimental year. Five mares resorbed/aborted once or twice during the 1st year. This was followed by a pregnancy that terminated in a live foal. Histopathological examinations of uterine biopsies showed a wide range of histopathological conditions, from absence of changes excessive for the mare's age and parity to the most seve...
Trophoblast-uterine interactions during equine chorionic girdle cell maturation, migration, and transformation. The structure of the equine chorionic girdle between days 28 and 42 of gestation was examined. Of particular interest were differentiation of trophoblastic cells within the girdle, adhesion between girdle and endometrium, invasion and displacement of the uterine epithelium, and the nature of the endometrium when girdle cells migrate into it to form endometrial cup cells. The chorionic girdle, identified initially as a band of tall columnar cells, becomes a stratified columnar epithelium indented by clefts and pits. Adhesion to and penetration through the endometrial luminal epithelium are rapi...
Mononuclear cell infiltration of the equine endometrium: immunohistochemical studies. Endometrial sections from mares with varying degrees of mononuclear cell infiltration were examined for immunoglobulin (Ig)A-, IgM-, IgG(T)- and IgG(Fc)-containing cells, luminal and glandular epithelial cell Ig-staining and free interstitial Ig-staining, using a peroxidase anti-peroxidase technique. Mares with mild to moderate (Group 2) and mares with severe diffuse mononuclear cell infiltration, superimposed by acute endometritis (Group 3), had significantly higher numbers of Ig-containing cells than genitally-normal mares (Group 1). The differences between Groups 1 and 3 were significant fo...
Regulation of mitogen- and TCGF-induced lymphocyte blastogenesis by prostaglandins and supernatant from equine embryos and endometrium. Immunosuppressive substances which interfere with lymphocyte blastogenesis are released in vitro by embryos and endometrium from mares in early pregnancy. Immunosuppression was not evident when tissues were cultured in the presence of indomethacin (a prostaglandin-synthesis inhibitor). Various prostaglandins (PGs) were added to equine lymphocytes and lymphocyte proliferation was measured after the addition of concanavalin A (Con A) or phytohaemagglutinin A (PHA). PGE2 and PGF2 alpha inhibited Con A-induced blastogenesis down to final concentrations of 1.8 x 10(-9) M and 1.3 x 10(-6) M, respect...
Medical problems of adult horses, as ranked by equine practitioners. This paper reports the results of a survey conducted among members of the American Association of Equine Practitioners, concerning medical problems of adult horses. A one-page questionnaire listing 36 medical problems grouped by body system was completed by 1,149 veterinarians. The top-ranked disease was colic, followed by viral respiratory tract disease, endometritis, dermatitis, and parasitism. When responses were evaluated by type of practice, location of practice, and number of veterinarians in the practice, ranking of the top 2 diseases was the same for the total respondents. Ranking of d...
Assessment of the breeding prognosis of mares using paired endometrial biopsy techniques. Paired endometrial biopsy samples were taken from 530 subfertile mares, before and after treatment (where indicated) and a period of sexual rest. Prognoses were made after each biopsy (Categories 1A-4A before treatment and Categories 1B-4B after treatment), using histopathological criteria similar to those described by Kenney and Doig (1986). Eighty-seven per cent of the mares were assigned to first biopsy prognosis Category 3A. The second biopsy prognosis produced a more even population distribution (10, 47, 40 and 3 per cent respectively for Category 1B, 2B, 3B and 4B mares). First biopsy Ca...
The effect of age and parity on the development of equine chronic endometrial disease. The results of a retrospective analysis of 3,804 endometrial biopsy specimens collected from non-pregnant mares during the course of routine equine stud farm practice demonstrates a significant and practically useful correlation between the severity of chronic degenerative endometrial disease (CDE) diagnosed and age of mare at the time of examination. There were significant correlations between the number of foals born and the mares' barren years prior to biopsy and the severity of CDE, but the differences were not sufficiently large to be useful. Correlations between the severity of chronic i...
Production of 5 alpha-dihydroprogesterone during late pregnancy in the mare. Changes in the progesterone metabolite 5 alpha-dihydroprogesterone (5 alpha-DHP) in maternal plasma in late gestation, and possible sites of production of this steroid were studied in pony and Thoroughbred mares by an enzyme-linked immunosorbant assay for 5 alpha-DHP. In Thoroughbred mares, plasma 5 alpha-DHP increased from 63.7 +/- 10.5 ng/ml (27 days pre-partum) to 161.7 +/- 30.8 ng/ml (1 day pre-partum) falling to 90.2 +/- 16.1 ng/ml on the day of parturition. In pony mares, values rose from 30.8 +/- 8.1 ng/ml (27 days pre-partum) to 79.1 +/- 30.8 ng/ml (3 days pre-partum) and then decrease...
Lodgement of the equine blastocyst in the uterus from fixation through endometrial cup formation. The equine blastocyst becomes fixed in position in the uterus on approximately Day 16 of gestation, but allantochorionic villi are not formed until about Day 50. The purpose of this study was to examine evidence that the blastocyst is orientated during this time period, and to determine what morphological features might assist retention of the position of the blastocyst within the uterus. Implantation sites were collected on Days 10-42 of gestation, and the reproductive tracts perfused with fixative for light and electron microscopic examination. The conceptus is found at the bend of a uterine...
Soluble oestrogen and progesterone receptors in the endometrium of the mare. Receptors for progesterone and oestrogen were measured in cytosol extracted from the endometrium of mares. Samples of endometrium were obtained from mares during the oestrous cycle and during other physiological and pathological states, and from mares with persistent endometritis. The concentration of binding sites was high around oestrus and early in dioestrus and was low by mid- to late dioestrus. Numbers of receptors were low in mares sampled on Day 15 of pregnancy and in mares in prolonged dioestrus, whereas receptor concentrations in ovariectomized mares were high. In 2 mares with endomet...
Pathological changes of the mare endometrium and genotypes for transferrin and ELA. Histological features of the endometrium, as assessed in biopsy samples, were related to Standardbred mare genotypes for transferrin, esterase (as a control) and equine leucocyte antigens (ELA). Pathological changes were found more frequently in each successively older age group of mares. Among mares aged 6-19 years, there were significant pathologic changes on first examination following an infertile breeding season for 46 of 90 (51%) of transferrin homozygotes and 50 of 146 (34%) of transferrin heterozygotes. The difference between the two groups was significant for the total data (chi 1(2) ...
Invasive equine trophoblast expresses conventional class I major histocompatibility complex antigens. Monoclonal antibodies and alloantisera were used in an indirect immunohistochemical assay to determine the expression of class I and class II Major Histocompatibility Complex (MHC) antigens by equine placental cells and the endometrial tissues at the fetal-maternal interface. MHC class I antigens were expressed at high density on the surface of the trophoblast cells of the chorionic girdle at days 32-36, just prior to their invasion of the endometrium. The mature gonadotrophin-secreting cells of the endometrial cups, which are derived from the chorionic girdle cells, had greatly reduced levels...
The effect of postpartum uterine lavage on foal heat pregnancy rate. Mares (n = 37) were treated on Days 2 and 4 post partum with a uterine lavage of 10 l of warm, sterile NaCl (0.9%) solution. Endometrial cytology and culture were performed on Day 7. Mares were bred on the first postpartum estrus by artificial insemination. Pregnancy rates were determined by ultrasound examination at Day 16 post ovulation. No differences were noted in degree of uterine inflammation or presence of uterine bacteria at Day 7 post partum between treated (n = 18) and control (n = 19) mares. Pregnancy rates at the first postpartum estrus for treated mares (55.5%) was not statistical...
Prolonged luteal activity in mares–a semantic quagmire. Prolonged luteal activity is one of the most formidable terminology challenges in mare reproductive biology. Prolonged luteal activity can be a result of persistence of an individual corpus luteum or the sequential development of luteal glands, each of which may have a normal life span. Luteal tissue can originate from an unovulated follicle or from an ovulation occurring during either follicular or luteal dominance. These complexities, together with ambiguous and inconsistent terminology, have resulted in confusion regarding those conditions which can be grouped broadly under the term prolong...
Variation in glycogen and mucins in the equine uterus related to physiologic and pathologic conditions. Histochemical stains were applied to six equine uterine biopsies representative of the physiologic breeding season, Spring and Fall transition, and Winter anestrus periods. These were compared with uterine biopsies from six mares with intrauterine urine pooling, eight mares used to study the uterine response to indwelling catheterization, and necropsy specimens from four pregnant mares at approximately 60 or 100 d of gestation. Alcian blue staining at pH 2.5 or 1.0 was used to identify the presence of carboxylated and sulfated acid mucins or only suflated acid mucins, respectively. Periodic ac...
Endometrial concentrations of ampicillin in mares after intrauterine infusion of the drug. Serum concentration of ampicillin, a semisynthetic penicillin, was measured in mares at various time intervals up to 24 hours after intrauterine infusion of 3 g of ampicillin. Blood samples were drawn immediately before infusion and at 1-, 4-, 10- and 24-hour intervals after infusion. At postinfusion hour 24, two endometrial biopsy specimens were obtained to measure endometrial concentrations of ampicillin. Blood was drawn twice as part of the 24-hour postinfusion sample collection, once before removal of the biopsy specimens and again 5 minutes after removal of the biopsy specimens. After dru...
Prostaglandin production by horse embryos and the effect of co-culture of embryos with endometrium from pregnant mares. Embryos, endometrial biopsies, and uterine lavage fluid were collected from pregnant and non-pregnant mares 14 days after ovulation. Embryos were cultured for 20.5 h with and without endometrial tissue from pregnant mares, and endometrial tissue was cultured alone. Endometrial content of PGF tended to be higher (P = 0.06) in non-pregnant than in pregnant mares, but the amount of PGF released from tissue during culture was similar for pregnant and non-pregnant mares. Lavage fluid from non-pregnant mares also tended (P = 0.08) to contain higher concentrations of PGF. Coincubation of embryos with...
