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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.
Oxytocin-neurophysin I mRNA abundance in equine uterine endometrium. A positive-feedback loop between luteal oxytocin and uterine prostaglandin F2 alpha (PGF) is a major signal for luteolysis in ruminants. Likewise, uterine PGF causes luteolysis in mares, but the involvement of oxytocin in this process is unclear. We wanted: 1) to determine if the oxytocin-neurophysin I (OT-NP I) gene is transcribed into mRNA in the endometrium of mares; and, if so, 2) to analyze relative changes in abundance of endometrial OT-NP I mRNA throughout the estrous cycle and during early stages of pregnancy. Endometrial biopsies were obtained from nonbred mares during estrus, and 5, ...
[Follicular dynamics after treatment with hCG for ovulation induction in mares]. In this study the use of hCG for induction of ovulation is described. Factors such as follicle diameter at the time of administration of hCG (3000 IE hCG i.v.), follicular growth after hCG and the rate of double ovulations were evaluated. A total of 168 mares presented for artificial insemination were used. In 249 estrous periods hCG was given to mares exhibiting standing estrous when a minimum follicle diameter of 30 mm and a well developed edema of the endometrium could be detected by ultrasonography. In nine estrous periods ovulation occurred within 24 hours after hCG. The majority of mares...
Morphologic comparisons among equine endometrium categories I, II, and III, using light and transmission electron microscopy. To evaluate whether the pathologic changes observed by light microscopy in endometrium of categories II and III were reflected by cellular changes and to describe differences in the endometrial cell ultrastructure during estrus and diestrus. Methods: 18 healthy mares. Methods: Endometrial tissues biopsied during the physiologic breeding season were categorized, using light microscopy, and were studied, using transmission electron microscopy (TEM). Results: Using TEM, glycogen granules were associated with giant mitochondria for all endometrial types during diestrus. Development of rough endopl...
Endometrial oxytocin receptor and uterine prostaglandin secretion in mares during the oestrous cycle and early pregnancy. Circulating concentrations of 13,14-dihydro-15-ketoprostaglandin F2 alpha (PGFM) were measured before and after administration of oxytocin and after endometrial biopsy, with or without uterine flushing performed per vaginam, on days 10, 14 and 18 after ovulation in nine pregnant and nine cyclic mares. Concentrations of oxytocin receptor were measured in endometrial biopsy samples. Neither pregnancy status nor time after ovulation affected basal PGFM concentrations. PGFM concentrations were increased after oxytocin administration on each of the days studied in cyclic mares; on day 14 the mean r...
Incidence and morphology of endometrial angiopathies in mares in relationship to age and parity. The morphology of endometrial blood vessels in uterine biopsy specimens from mares of varying age and reproductive status was examined by light (n = 117) and electron microscopy (n = 13), and additionally after elastase digestion (n = 86). Inflammatory vascular alterations were observed in 20.5% of the specimens. Smaller and larger arterial and venous vessels demonstrated mild to severe degenerative lesions. Unaltered vessels were detected only in maiden mares. Vessels in older maiden mares were frequently affected by angiosclerotic changes, characterized by mild to moderate perivascular and i...
Transfer of a uterine lipocalin from the endometrium of the mare to the developing equine conceptus. One of the major, progesterone-dependent proteins secreted into the uterine lumen of the mare is a 19-kDa lipocalin (P19). It associates strongly with the embryonic capsule that envelops the young horse conceptus in early gestation, suggesting that it may be involved in sustaining early development. However, it was not known whether the protein was transported through the capsule and/or trophoblast layer and into the yolk sac cavity. To address this question, polyclonal antisera were raised against a C-terminal peptide (based on the deduced amino acid sequence of P19) and a recombinant-derived...
Endometrial connexin expression in the mare and pig: evidence for the suppression of cell-cell communication in uterine luminal epithelium. This investigation examines the relationship between implantation strategy and gap junction protein expression in uterine endometrium. The pattern of gap junction and connexin protein expression was analyzed in porcine and equine endometrium from cycling and pregnant animals using electron microscopy and immunocytochemistry. Functional analysis of cell-cell communication was also monitored by laser cytometry in primary cultures of endometrial epithelial cells. Gap junctions were detected in endometrial stroma of cycling and pregnant animals, which was correlated with immunoreactive Cx43 within...
Expression of epidermal growth factor and its receptor in equine placental tissues. Northern blot and in situ hybridization techniques have demonstrated a marked increase in mRNA encoding epidermal growth factor (EGF) in the endometrium of mares, coincident with the start of interdigitation between the allantochorion and endometrium during placentation. In the present study, the unusually high EGF expression in the epithelium of the endometrial glands was shown to be maintained until at least day 250 of gestation (term = 320-340 days) in mares carrying normal horse conceptuses. However, in mares carrying failing donkey-in-horse pregnancies created by embryo transfer, EGF expr...
The equine immune response to endometrial cups. Out of all the areas of comparative immunological study in the horse, the field of reproductive immunology has proven to be one of the most fertile and exciting. Maternal immunological interactions with the fetus involve a set of events which prevent maternal rejection of trophoblastic tissue invading the uterus, and at the same time control this invasion to regulate growth and prevent damage to maternal tissues. Unique features of equine placentation make it exceptionally well-suited to studying these immunological interactions.
[Examination of the appropriateness of anamnestic and clinical parameters for the prediction of the course of pregnancy under field conditions]. In this paper, fertility relevant parameters which are routinely examined in practice were evaluated on the basis of their correlation to one another and their influence on the foaling rates and incidence of early embryonic death in 175 brood mares of the Hanover breeding stock. The aim was to evaluate the suitability of these parameters for inclusion in a scheme for increasing the precision of predicting the subsequent course of pregnancy, as compared to such prognoses based exclusively on the histological evaluation of the endometrium. After establishing the breeding history and completing a...
Equine inhibin/activin beta A-subunit mRNA is expressed in the endometrial gland, but not in the trophoblast, during pregnancy. The expression of both inhibin alpha- and inhibin/activin beta A-subunit mRNA was examined in equine uteroplacental tissues collected during pregnancy (days 90 to 300). Northern blot analysis revealed that 5 transcripts (7.0, 4.1, 3.4, 2.6, 1.5 kb) of beta A-subunit were present, and the most abundantly expressed transcript was the 1.5 kb one. Relatively high levels of the 1.5 kb transcript were seen in the second trimester of pregnancy compared to what was found in the third trimester. To identify the tissue localization of beta A-subunit mRNA, in situ hybridization was performed, and the pos...
A developmental switch in expression from blastocyst to endometrial/placental-type cytochrome P450 aromatase genes in the pig and horse. Pig blastocysts exhibit a transient period of estrogen production at periimplantation, with a second, more sustained period of estrogen synthesis occurring in endometrium and placenta at later pregnancy. Previously we reported the isolation of cDNA clones encoding a novel isoform of cytochrome P450 aromatase (the terminal enzyme in the estrogen biosynthetic pathway) from porcine periimplantation blastocysts. The present study investigated pregnancy-associated expression, in blastocysts and maternal reproductive tract tissues of this and an additional mRNA transcript encoding a distinct P450 ar...
Intrauterine fluid accumulation in oestrous mares. Intrauterine fluid (IUF) was collected using a tampon from mid-oestrous mares (n = 57) with and without ultrasonically detectable accumulations of free intraluminal fluid. Bacteria were cultured and neutrophils counted from all samples (n = 57). Total protein concentration, trypsin-inhibitor capacity (TIC), and plasmin, beta-glucuronidase (B-Gase) and N-acetyl-beta-D-glucosaminidase (NAGase) activities were determined in 27 IUF samples. The motility of spermatozoa in the presence of IUF, IUF extended with Kenney's medium (1:1) and Kenney's medium alone was analysed in 9 samples using a Hamilto...
The equine endometrial mast cell during the puerperal period: evaluation of mast cell numbers and types in comparison to other inflammatory changes. Endometrial biopsies of 44 broodmares were histologically examined on days 3, 6, and 9 postpartum. The mares were subdivided into three groups according to the course of the puerperal period. In 29 mares, parturition and expulsion of the placenta was normal, six mares showed dystocia, and in nine mares, the placenta was retained for > 2 hours. Tissue samples were evaluated histologically, and the average numbers of granulocytes, lymphocytes, macrophages, siderophages, and mast cells was determined. Protease content of mast cells was examined with a double-enzyme immunohistochemical staining...
Relationship between endometrial oxytocin receptors and oxytocin-induced prostaglandin F2 alpha release during the oestrous cycle and early pregnancy in pony mares. The effect of transcervical endometrial biopsy on the concentrations of plasma immunoreactive oxytocin and 15-keto-13,14-dihydro-prostaglandin F2 alpha (PGFM) was studied in 18 pony mares on days 8, 12 and 14 after ovulation, days 12 and 14 of early pregnancy and at oestrus. Five biopsy specimens were taken within 15 min and consecutive specimens from each mare were pooled two (A) and three (B) together for measurement of the number of oxytocin receptors. Blood samples were collected at intervals of 5 min for 15 min beginning just before the initial biopsy. Biopsy procedure elicited prompt oxy...
Histomorphological endometrial status and influence of oxytocin on the uterine drainage and pregnancy rate in mares. The aim of this field study was to examine the influence of the uterotonic substance oxytocin in 2 different therapeutic dosages of 15 and 25 i.u., respectively on the uterine drainage of oestrous mares and on their fertility. In addition endometrial biopsies of mares with and without intrauterine fluid accumulations around the time of ovulation were evaluated histomorphologically regarding the aetiology of susceptibility to uterine infection. A population of 59 Hanoverian Warmblood mares was used in this study. The mares were divided into Group A (mares with intrauterine fluid accumulations [...
Pharmacokinetics of enrofloxacin in adult horses and concentration of the drug in serum, body fluids, and endometrial tissues after repeated intragastrically administered doses. To investigate the pharmacokinetics of enrofloxacin in adult horses. Methods: 2-dose oral and i.v. cross-over trial followed by multiple oral doses. Methods: 8 clinically normal adult horses. Methods: Enrofloxacin was administered at dosages of 2.5 mg/kg of body weight to 4 horses and 5.0 mg/kg to 4 other horses. Each dose was given by the intragastric and i.v. routes, using a cross-over design. After the first intragastric dose, 5 additional doses were administered at 12-hour intervals. Enrofloxacin concentrations were measured in serum, synovial fluid, peritoneal fluid, urine, CSF, and endom...
Failure of endometrial cup development in the donkey-in-horse model of equine abortion. The mature preinvasive chorionic girdles of horse, mule, donkey and extraspecies donkey-in-horse conceptuses, and the very young endometrial cups on d 37 of gestation in mares carrying horse, mule and transferred donkey-in-horse conceptuses, were compared histologically and ultrastructurally to determine possible mechanisms underlying failure of endometrial cup development in the donkey-in-horse model of equine abortion. The progenitor chorionic girdle from the failing donkey-in-house pregnancy was similar in size to the normal donkey chorionic girdle but the trophoblast cells within the forme...
Influence of chronic degenerative endometritis (endometrosis) on placental development in the mare. Placentation between 80 and 220 days of gestation was studied by measurement of fetal dimensions and gross, light and transmission and scanning electron microscopic examinations of the allantochorion and endometrium from 4 fertile mares with no, or very mild, endometrial histopathology and 6 subfertile Thoroughbred mares suffering varying degrees of age-related chronic degenerative endometritis (endometrosis). Spontaneously occurring twin gestation was observed in 3 animals. Several of the subfertile mares had endometrial cysts which showed 2 distinct features during pregnancy: those located n...
Lymphocyte subsets in the endometrium of genitally normal mares and mares susceptible to endometritis. The density and distribution of MHC Class II positive cells and subpopulations of lymphocytes were studied in the endometrium of genitally normal mares and mares susceptible to endometritis. In genitally normal mares, more MHC Class II positive cells were present in the epithelium and stratum compactum during oestrus than dioestrus. Significantly more CD4+ and CD8+ lymphocytes were present in the stratum compactum than in the stratum spongiosum. CD4+ lymphocytes were present in greater numbers than CD8+ lymphocytes in the stratum compactum but approximately equal numbers were present in the st...
Tissue and serum concentrations of amikacin after intramuscular and intrauterine administration to mares in estrus. Concentrations of amikacin in endometrial tissue and plasma were studied in mares in estrus after intrauterine infusion of 1.0 or 2.0 g once a day for 3 consecutive d, and after 9.7 or 14.5 mg/kg body weight (BW) had been injected intramuscularly once a day for 3 consecutive d to determine concentrations of amikacin sulfate in plasma and endometrial tissues, and whether parenteral administration provides any advantages over intramuscular infusion. No amikacin was detected in serum at the 1.0 g dose. At the infusion dose of 2.0 g once a day, very low levels of serum amikacin were detected at 1 ...
Differential suppression of endometrial prostaglandin F2alpha by the equine conceptus. Prostaglandin F2alpha secretion by the uterine endometrium between Days 13 and 14 postovulation causes luteal regression in mares. A mechanism involving interruption or suppression of this secretion causes pregnancy to be maintained. The present study was designed to determine the age of the conceptus when maximal suppression of PGF2alpha secretion occurs. Mares were examined daily during estrus with ultrasonography (day 0 = day of ovulation). Conceptus tissues were recovered nonsurgically on Days 9 (n = 7), 12 (n = 5), 13 (n = 5), and 16 (n = 7) and uterine biopsies on Day 14. Both uterine an...
Transforming growth factor beta 1 expression in the endometrium of the mare during placentation. In situ hybridization, Northern blotting, and immunohistochemical techniques were used to study the expression of transforming growth factor beta 1 (TGF beta 1) in the endometrium of the mare during the first 150 days of pregnancy (term = 330-340 days). In situ hybridization using an oligonucleotide (45mer) probe, based on a homologous region within all known mammalian TGF beta 1 DNA sequences, demonstrated TGF beta 1 mRNA accumulation in the glandular and lumenal epithelial cells of the endometrium from day 33 onwards which corresponds to the time of implantation (day 33-45). Expression in th...
[Fertility in mares after disturbed or undisturbed puerperium; evidence from clinical, microbiologic and hormone analysis]. Because of the mare's ability to conceive very soon post partum a thoroughly performed control of the puerperal period is of particular importance. In addition to cytological and histological examinations of the uterus, rectal palpation and vaginoscopic inspection as well as microbiological examinations of uterine swabs and the evaluation of the mare's hormonal status during the puerperal period provide useful information which can be used either prognostically or to initiate a specific therapy. 55 mares were examined on days 3, 6 and 9 post partum. Rectal palpation, vaginoscopic inspection, m...
Ultrastructure of the secretory endometrium during oestrus in young maiden and foaled mares. Cyclical accumulation of uterine fluid occurs during oestrus and is often seen in excessive volumes in mares considered susceptible to endometritis. Since the mechanisms behind the formation of free uterine fluid remain to be clarified, the fine structure of the secretory equine endometrium was studied in biopsies collect during videoendoscopy from 14 endometritis-free, 4-9-year-old mares during oestrus. A distinct oedema of the tunica mucosa was evident. The surface epithelium had both ciliated and nonciliated cells and, particularly at the uterine body, often presented intra-epithelial macro...
A novel uterine protein that associates with the embryonic capsule in equids. An apparently unique protein produced in large quantities by the endometrium of the mare which adheres to, or is incorporated into, the acellular capsule that surrounds the equine conceptus in early pregnancy, has been characterized and partially sequenced. It has a molecular mass of approximately 18 kDa on SDS-PAGE gels and is nonglycosylated as assessed by a sensitive carbohydrate detection kit. Comparison of its first 24 amino-terminal amino acids with all entries in the databases failed to show any significant identity with any other protein sequence. Secretion of the protein appears to be...
The maternal leucocyte response to the endometrial cups in horses is correlated with the developmental stages of the invasive trophoblast cells. Invading trophoblasts form endometrial cups in the endometrium of the pregnant mare. In the present study we characterized the maternal leucocyte response to endometrial cups from their formation to their regression. The maternal leucocyte response was correlated with the stages of trophoblast development. (1) Aggregates of CD4+ and CD8+ cells were present between the migrating and differentiating endometrial cup trophoblasts and surrounding the forming endometrial cups. (2) Numbers of CD4+ cells within the mature endometrial cups were much reduced. At the periphery of the endometrial cups CD4...
