Videoendoscopic evaluation of the mare's uterus: I. Findings in normal fertile mares

Activities of matrix metalloproteinase-2 and -9 in amniotic fluid at parturition in mares with normal and high-risk pregnancy

The matrix metalloproteinases (MMPs) are a family of enzymes involved in extracellular matrix remodeling. MMPs are secreted in a latent form and activated by local and infiltrating cells. MMP-2 and -9 are the most studied in reproduction and have been detected in bovine, ovine, equine and human placenta. There is only one study on MMPs in the equine amniotic fluid (AF) reporting a decrease in the activity of MMP-2 in case of premature delivery. The aim of this study was focused on MMP-2 and -9 activity in AF collected at parturition from mares with normal or high-risk pregnancy. High-risk pregnancy was defined as a history of premature udder development/lactation, increase of combined thickness of the uterus and placenta, vulvar discharge and/or mare's systemic illness. The diagnosis of placental insufficiency was confirmed retrospectively after macroscopic and histopatologic examination of the placenta. AF was collected by needle puncture of the amnion within 5 min after its appearance through the vulva. The activity of MMP-2 and -9 was analyzed by in-gel zymography allowing the evaluation of both latent and active forms. Twenty mares with normal pregnancy (group 1) and 8 mares with high-risk pregnancy (group 2) were included. All mares in group 2 had a high-risk pregnancy with a diagnosis of placental insufficiency associated with placental villous hypoplasia, placentitis or placental edema. The bands relative to latent and active forms of MMP-2 were clearly visible in both groups and the activity of latent (P = 0.010) and active (P = 0.004) forms was lower in the AF samples of group 2. The band of the latent form of MMP-9 was visible in 17/20 samples of group 1, while it was completely absent in all samples of group 2. In contrast, the band of the active form was clearly visible and with a greater activity in AF samples of group 2 (P = 0.002). Placental dysfunction seems to induce a lower MMP-2 activity and a higher MMP-9 activity through the release of pro-inflammatory cytokines. Because fetal pulmonary secretions are a likely source of gelatinases in AF during late gestation, the increased MMP-9 activity could be related to fetal distress. These data provide a starting point to better understand the role of MMPs in equine pregnancy, although it should be confirmed in a larger and more homogeneous population of mares with high-risk pregnancy.

Use of Hysteroscopy for Diagnosing Causes of Infertility in Camelids

Hysteroscopy in alpacas and llamas allows for the identification of abnormalities on the surface or within the endometrium that cannot be identified with other methods. Hysteroscopy also allows for site-directed endometrial cytology, culture, and biopsy to achieve a definitive diagnosis. Even when no cause for infertility can be found, previously infertile females tend to become pregnant and maintain their pregnancies to term following the hysteroscopic procedure. This therapeutic effect may be a response to pre-hysteroscopy estrogen treatment, dilation of the uterine horns during hysteroscopy, and/or posttreatment uterine lavages. Complications following hysteroscopy have not been reported in camelids.

Half a century of equine reproduction research and application: A veterinary tour de force

Over the past 50 years, per season pregnancy rate in Thoroughbred mares have risen from 70 to >90% and foaling rates from 55 to >80%. Some of the significant pharmacological treatments and diagnostic methods which have driven this marked improvement in breeding efficiency are reviewed. They include the application of artificial lighting to hasten the onset of ovulatory oestrous cyclicity in early Spring, rapid steroid hormone assays to aid in determining the stage and normality of the mare's cycle, prostaglandin analogues, synthetic progestagens and Gonadotrophin-releasing Hormone (GnRH) analogues to better control and manipulate her cycle to good effect, transrectal ultrasound scanning to monitor follicle growth, endometrial architecture and ovulation and to allow accurate, early pregnancy diagnosis thereby enabling successful ablation of one of twin conceptuses. Also, flexible videoendoscopy to monitor physiological and pathological changes in the uterine endometrium and rigid laparoscopy to apply prostaglandin to the oviducts to dislodge and clear suspected blockages of them to restore fertility. The outbreak of Contagious Equine Metritis in Newmarket in the spring of 1977 and the swabbing-related changes to mare and stallion management, plus the improved veterinary hygiene methods, which followed are also recounted. The past half century has witnessed many technical and therapeutic advances that have enhanced tremendously the diagnostic and treatment capabilities of studfarm veterinary surgeons. They, in turn, have improved greatly the efficiency of breeding Thoroughbreds and other types of horses.

Colour analysis of the equine endometrium: comparison of spectrophotometry and computer-assisted analysis of photographs within the L*a*b* colour space system

The aims of this study were to compare two different methods of quantifying the colour of the luminal surface of the equine endometrium and to relate the results to histopathological evidence of inflammation and fibrosis. The mucosal surfaces of 17 equine uteri obtained from an abattoir were assessed using a spectrophotometer and by computer-assisted analysis of photographs. Values were converted into L(*)a(*)b(*) colour space. Although there was significant correlation between the two methods of quantification, variations in 'brightness', 'red' and 'yellow' values were noted. Within a given uterus, measurements using the spectrophotometer did not differ significantly. Using photographic analysis, brightness differed between horns, although no differences in chromaticity were found. Histopathological classification of changes within endometria corresponded to measured differences in colour. Extensive fibrosis was associated with increased brightness and decreased chromaticity using both methods. Inflammation correlated with reduced chromaticity, when measured by spectrophotometry, and with reduced brightness and yellow values, when assessed photographically. For this technique to gain wider acceptance as a diagnostic tool, e.g. for the endoscopic evaluation of uterine mucosae in vivo, standardised illumination techniques will be required so that colours can be compared and interpreted accurately.

Clinical and subclinical endometritis in the mare: both threats to fertility

Endometritis, a major cause of mare infertility arising from failure to remove bacteria, spermatozoa and inflammatory exudate post-breeding, is often undiagnosed. Defects in genital anatomy, myometrial contractions, lymphatic drainage, mucociliary clearance, cervical function, plus vascular degeneration and inflamm-ageing underlie susceptibility to endometritis. Diagnosis is made through detecting uterine fluid, vaginitis, vaginal discharge, short inter-oestrous intervals, inflammatory uterine cytology and positive uterine culture. However, these signs may be absent in subclinical cases. Hypersecretion of an irritating, watery, neutrophilic exudate underlies classic, easy-to-detect streptococcal endometritis. In contrast, biofilm production, tenacious exudate and focal infection may characterize subclinical endometritis, commonly caused by Gram-negative organisms, fungi and staphylococci. Signs of subclinical endometritis include excessive oedema post-mating and a white line between endometrial folds on ultrasound. In addition, cultures of uterine biopsy tissue or of small volume uterine lavage are twice as sensitive as guarded swabs in detecting Gram-negative organisms, while uterine cytology is twice as sensitive as culture in detecting endometritis. Uterine biopsy may detect deep inflammatory and degenerative changes, such as disruption of the elastic fibres of uterine vessels (elastosis), while endoscopy reveals focal lesions invisible on ultrasound. Mares with subclinical endometritis require careful monitoring by ultrasound post-breeding. Treatments that may be added to traditional therapies, such as post-breeding uterine lavage, oxytocin and intrauterine antibiotics, include lavage 1-h before mating, carbetocin, cloprostenol, cervical dilators, systemic antibiotics, intrauterine chelators (EDTA-Tris), mucolytics (DMSO, kerosene, N-acetylcysteine), corticosteroids (prednisolone, dexamethasone) and immunomodulators (cell wall extracts of Mycobacterium phlei and Propionibacterium acnes).

Immunolocalisation of the uterine secretory proteins uterocalin, uteroferrin and uteroglobin in the mare's uterus and placenta throughout pregnancy

Previous studies have shown that the equine uterus produces many progesterone-dependent proteins throughout gestation. In particular, uterocalin and uteroferrin are detectable using electrophoresis or blot analyses but information regarding the immunohistochemical placental distribution of these two proteins is rare and information regarding uteroglobin is still lacking. The aim of the present study was to co-immunolocalise these three secretory proteins in the mare's uterus throughout gestation in an effort to understand their functional role in the maintenance of pregnancy. Therefore, endometrial biopsy samples were obtained from 20 pregnant mares between 16 and 309 days of gestation and labelled immunohistochemically for uteroglobin, uteroferrin and uterocalin. Uteroferrin remained detectable in almost every endometrial gland at all stages but with an increase in staining intensity as gestation advanced. The most progesterone-dependent protein, uterocalin, showed variable staining throughout gestation with the most intense labelling in early pregnancy and during the period of endometrial cup reaction. Uteroglobin secretion was only detectable in traces and only in individual glands throughout gestation. The results indicate that uterocalin and uteroferrin, but not uteroglobin, may play important roles in supplying nutrients for the conceptus, thereby contributing to the maintenance of pregnancy. However, further investigations are necessary to understand the role of uteroglobin during gestation.

Mucus and the mare: How little we know

Uterine infections are a major cause of infertility, but the role of mucus in equine uterine defense is not well understood. Mucociliary currents play an important role in protecting mucous membranes, including the upper and lower respiratory tracts of mammals, and are required for feeding and oxygenation of many aquatic invertebrates. Although phagocytosis has long been considered the first line of uterine defense in the mare, there are concerns about its efficacy in the uterine lumen. Additional local defenses, such as mucociliary currents, have therefore been proposed. The uterine epithelium exhibits alternating mucus-secreting and ciliated cells supporting a mucopolysaccharide blanket, features shared with mucociliary membranes throughout the animal kingdom. Gross uterine anatomy, such as continuity of uterine and cervical folds, may indicate adaptations to mucociliary clearance. In addition, ciliated cells obtained in uterine lavages often display motility. Disruptions of mucociliary clearance play major roles in pathogenesis of mucosal infections in humans, including pneumonia, chronic sinusitis, and otitis media. Establishing drainage is a major goal of therapy in treatment of chronic sinusitis, hastening return of mucociliary function. Similar disruptions may occur in equine uterine infections, associated with accumulations of uterine fluid, loss of endometrial folds, and cervical trauma. Possible clinical implications of mucociliary clearance in the mare are discussed, however the role of mucociliary clearance in the mare remains speculative.

Advanced insemination techniques in mares

Advanced artificial insemination techniques, such as deep uterine,hysteroscopic, oviductal, and intrafollicular insemination, are described in the context of the different types of spermatozoa that are now available for insemination, including fresh, chilled, frozen,sex-sorted, and epididymal spermatozoa. The implementation of these new technologies answers and poses questions about the interactions of sperm and oocytes in vivo.

Making sense of equine uterine infections: the many faces of physical clearance

Equine uterine infections inflict major losses on the equine industry. Persistent inflammation of the oviduct and uterus leads to loss of the conceptus and mares susceptible to infection have weakened uterine defences partly due to retention of inflammatory exudate. Bacteria may trigger inflammation, resist phagocytosis, or adhere to the endometrium and types of infection range from genital commensals in susceptible mares to reproductive pathogens in normal mares. Uterine infections are diagnosed by history, detection of uterine inflammation, and isolation of typical organisms and susceptible mares may be identified by detection of intrauterine fluid during oestrus, or at 6-48 h post-breeding. Therapy includes oxytocin, uterine lavage, antibiotics, and prostaglandin analogues and clinical studies indicate additive benefits of oxytocin and antibiotics. Improved conception rates have been associated with autologous, intrauterine plasma, despite controversy about its bactericidal efficacy. Because of the potential for endometrial damage, intrauterine antiseptics require caution.

Use of a hand-assisted laparoscopic technique for removal of a uterine leiomyoma in a standing mare

A 20-year-old Thoroughbred mare was evaluated because of a 2-year history of infertility. The mare had normal estrous cycles and had been bred 7 times by different stallions. Ultrasonographic examination revealed a homogeneous hyperechoic intramural mass in the tip of the right uterine horn; the mass was also detected via hysteroscopy Unilateral ovariectomy and partial hysterectomy were performed by use of a hand-assisted laparoscopic technique. Leiomyoma was diagnosed via histologic examination of the mass. Unilateral ovariectomy and partial hysterectomy are recommended in mares with leiomyoma in a uterine horn, especially if the tumor is associated with infertility. The hand-assisted laparoscopic technique allows direct visualization of abdominal structures and accurate placement of ligatures without applying tension on the broad ligament, and eliminates the risks and costs of general anesthesia.

Efeito dos fixadores formalina e Bouin na preservação de biópsias do endométrio de éguas após inclusão em resina plástica

Biópsias do endométrio de 16 éguas sexualmente maduras, em estro e diestro, foram processadas para microscopia de luz utilizando-se fixação em formalina ou Bouin e inclusão em resina plástica à base de glicol metacrilato. Análises morfológicas de 46 biópsias demonstraram que o epitélio de revestimento do endométrio, o epitélio glandular, as fibras do tecido conjuntivo e os diferentes tipos celulares presentes na lâmina própria, tais como fibroblastos, plasmócitos, mastócitos e macrófagos, apresentaram-se melhor preservados quando os fragmentos de tecidos foram fixados em formalina. O epitélio de revestimento mostrou grau mais acentuado de retração tecidual nas biópsias fixadas em Bouin, independente da fase do ciclo estral. A fixação em formalina aliada à inclusão em resina plástica resultou em melhor resolução das células ao microscópio de luz, permitindo um estudo citológico mais acurado do endométrio eqüino.

An overview of low dose insemination in the mare

The need for relatively high numbers of spermatozoa for artificial insemination limits our application of recently available technologies such as sex-sorted semen. The fertility of two different methods of low dose insemination using fresh, frozen and sex-sorted semen are compared in this overview. Satisfactory conception rates are described using very low doses of spermatozoa inseminated by either hysteroscopic or deep uterine insemination methods, proving the stallion is fully fertile. The hysteroscopic method appears to give higher conception rates when inseminating fewer than 5 x 10(6) spermatozoa and is therefore, the preferred method of insemination for sex-sorted spermatozoa. However, hysteroscopic deposition of low numbers of spermatozoa from infertile stallions does not appear to improve their fertility.

Hysteroscopic insemination of low numbers of flow sorted fresh and frozen/thawed stallion spermatozoa

The objective of this experiment was to determine the effects of flow cytometric sorting and freezing on stallion sperm fertility. A 2 x 2 factorial design was used to delineate effects of flow sorting and freezing spermatozoa. Oestrus was synchronised (July-August) in 41 mares by administering 10 ml altrenogest (2.2 mg/ml) per os for 10 consecutive days, followed by 250 microg cloprostenol i.m. on Day 11. Ovulation was induced by administering 3,000 iu hCG i.v. either 6 h (fresh spermatozoa) or 30 h (frozen/thawed spermatozoa) prior to insemination. Mares were assigned randomly to one of 4 sperm treatment groups. Semen was collected from 2 stallions with an artificial vagina and processed for each treatment. Treatment 1 (n = 10 mare cycles) consisted of fresh, nonsorted spermatozoa and Treatment 2 (n = 16 mare cycles) of fresh, flow sorted spermatozoa. Spermatozoa to be sorted were stained with Hoechst 33342 and sorted into X- and Y-chromosome-bearing populations based on DNA content using an SX MoFlo sperm sorter. Treatment 3 (n = 16 mare cycles) consisted of frozen/thawed nonsorted spermatozoa (frozen at 33.5 x 106 sperm/ml in 0.25 ml straws) and Treatment 4 (n = 15 mare cycles) of flow sorted frozen/thawed spermatozoa (frozen at 64.4 x 10(6) sperm/ml). Concentrations of sperm in both cryopreserved treatments were adjusted, based on predetermined average post-thaw motilities, so that each insemination contained approximately 5 x 10(6) motile spermatozoa. Hysteroscopic insemination of 5 x 10(6) motile spermatozoa in a volume of 230 microd was used for all treatments. Pregnancy was determined ultrasonographically 16 days postovulation. No differences were found (P>0.1) in the pregnancy rates for mares inseminated with fresh nonsorted (4/10 = 40.0%), fresh flow sorted (6/16 = 37.5%), frozen/thawed nonsorted (6/16 = 37.5%) and flow sorted frozen/thawed spermatozoa (2/15 = 133%). Pregnancy rates tended (P = 0.12) to be lower following insemination of frozen/thawed flow sorted spermatozoa. Further studies are needed with a larger number of mares to determine if fertility of flow sorted frozen/thawed spermatozoa can be improved.

Hysteroscopic insemination of mares with low numbers of nonsorted or flow sorted spermatozoa

The objectives of this study were 1) to compare pregnancy rates resulting from 2 methods of insemination using low sperm numbers and 2) to compare pregnancy rates resulting from hysteroscopic insemination of 5 x 106 nonsorted and 5 x 106 spermatozoa sorted for X- and Y-chromosome-bearing populations (flow sorted). Semen was collected with an artificial vagina from 2 stallions of known acceptable fertility. Oestrus was synchronised (June to July) in 40 mares, age 3-10 years, by administering 10 ml altrenogest orally for 10 consecutive days, followed by 250 microg cloprostenol i.m. on Day 11. All mares were given 3000 iu hCG i.v. at the time of insemination to induce ovulation. Mares were assigned randomly to 1 of 3 treatment groups: mares in Treatment 1 (n = 10) were inseminated with 5 x 10(6) spermatozoa deposited deep into the uterine horn with the aid of ultrasonography. Mares in Treatment 2 (n = 10) were inseminated with 5 x 10(6) spermatozoa deposited onto the uterotubal junction papilla via hysteroscopic insemination. Mares in Treatment 3 (n = 20) were inseminated using the hysteroscopic technique with 5 x 10(6) flow sorted spermatozoa. Spermatozoa were stained with Hoechst 33342 and sorted into X- and Y-chromosome-bearing populations based on DNA content using an SX MoFlo sperm sorter. Pregnancy was determined ultrasonographically at 16 days postovulation. Hysteroscopic insemination resulted in more pregnancies (5/10 = 50%) than did the ultrasound-guided technique (0/10 = 0%; P<0.05) when nonsorted sperm were inseminated. Pregnancy rates were not significantly lower (P>0.05) when hysteroscopic insemination was used for sorted (5/20 = 25%) and nonsorted spermatozoa (5/10 = 50%). Therefore, hysteroscopic insemination of low numbers of flow sorted stallion spermatozoa resulted in reasonable pregnancy rates.

Low dose insemination of mares using non-sorted and sex-sorted sperm

Mares are generally inseminated with 500 million progressively motile fresh sperm and approximately 1 billion total sperms that have been cooled or frozen. Development of techniques for low dose insemination would allow one to increase the number of mares that could be bred, utilize stallions with poor semen quality, extend the use of frozen semen, breed mares with sexed semen and perhaps reduce the incidence of post-breeding endometritis. Three low dose insemination techniques that have been reported include: surgical oviductal insemination, deep uterine insemination and hysteroscopic insemination. Insemination techniques: McCue et al. [J. Reprod. Fert. 56 (Suppl.) (2000) 499] reported a 21% pregnancy rate for mares inseminated with 50,000 sperms into the fimbria of the oviduct. Two methods have been reported for deep uterine insemination. In the study of Buchanan et al. [Theriogenology 53 (2000) 1333], a flexible catheter was inserted into the uterine horn ipsilateral to the corpus luteum. The position of the catheter was verified by ultrasound. Insemination of 25 million or 5 million spermatozoa resulted in pregnancy rates of 53 and 35%, respectively. Rigby et al. [Proceedings of 3rd International Symposium on Stallion Reproduction (2001) 49] reported a pregnancy rate of 50% with deep uterine insemination. In their experiment, the flexible catheter was guided into position by rectal manipulation.More studies have reported the results of using hysteroscopic insemination. With this technique, a low number of spermatozoa are placed into or on the uterotubal junction. Manning et al. [Proc. Ann. Mtg. Soc. Theriogenol. (1998) 84] reported a 22% pregnancy rate when 1 million spermatozoa were inserted into the oviduct via the uterotubal junction. Vazquez et al. [Proc. Ann. Mtg. Soc. Theriogenol. (1998) 82] reported a 33% pregnancy rate when 3.8 million spermatozoa were placed on the uterotubal junction. Recently, Morris et al. [J. Reprod. Fert. 188 (2000) 95] utilized the hysteroscopic insemination technique to deposit various numbers of spermatozoa on the uterotubal junction. They reported pregnancy rates of 29, 64, 75 and 60% when 0.5, 1, 5 and 10 million spermatozoa, respectively, were placed on the uterotubal junction. Insemination of sex-sorted spermatozoa: One of the major reasons for low dose insemination is insemination of X- or Y-chromosome-bearing sperm. Through the use of flow cytometry, spermatozoa can be accurately separated into X- or Y-bearing chromosomes. Unfortunately, only 15 million sperms can be sorted per hour. At that rate, it would take several days to sort an insemination dose containing 800 million to 1 billion spermatozoa. Thus, low dose insemination is essential for utilization of sexed sperm. Lindsey [Hysteroscopic insemination with low numbers of fresh and cryopreserved flow-sorted stallion spermatozoa, M.S. Thesis, Colorado State University, Fort Collins, CO, USA, 2000] utilized either deep uterine insemination or hysteroscopic insemination to compare pregnancy rates of mares inseminated with sorted, fresh stallion sperm to those inseminated with non-sorted, fresh stallion sperm. Hysteroscopic insemination resulted in more pregnancies than ultrasound-guided deep uterine insemination. Pregnancy rate was similar for mares bred with either non-sorted or sex-sorted spermatozoa. In a subsequent study, Lindsey et al. [Proceedings of 5th International Symposium on Equine Embryo Transfer (2000) 13] determined if insemination of flow-sorted spermatozoa adversely affected pregnancy rates and whether freezing sex-sorted spermatozoa would result in pregnancies. Mares were assigned to one of four groups: group 1 was inseminated with 5 million non-sorted sperms using hysteroscopic insemination; group 2 was inseminated with 5 million sex-sorted sperms using hysteroscopic insemination; group 3 was inseminated with non-sorted, frozen-thawed sperm; and group 4 was inseminated with sex-sorted frozen sperm. Pregnancy rates were similar for mares inseminated with non-sorted fresh sperm, sex-sorted fresh sperm and non-sorted frozen sperm (40, 37.5 and 37.5%, respectively). Pregnancy rates were reduced dramatically for those inseminated with sex-sorted, frozen-thawed sperm (2 out of 15, 13%). These studies demonstrated that hysteroscopic insemination is a practical and useful technique for obtaining pregnancies with low numbers of fresh spermatozoa or low numbers of frozen-thawed spermatozoa. Further studies are needed to determine if this technique can be used to obtain pregnancies from stallions with poor semen quality. In addition, further studies are needed to develop techniques of freezing sex-sorted spermatozoa.

Horse conceptuses secrete insulin-like growth factor-binding protein 3

Insulin-like growth factor-I (IGF-I) promotes early embryonic development in several species. In the rabbit, IGF-I binds to the embryonic coats from Day 3 of development onward by a 38-kDa protein that is probably insulin-like growth factor-binding protein 3 (IGFBP3). In the present study, ligand, Western, and Northern blot analyses were used to demonstrate the presence of IGF-I-binding activity, several immunoreactive IGFBP3 proteins, and IGFBP3 mRNA in horse conceptuses with particularly large amounts of immunoreactive IGFBP3 in the conceptus capsule. In addition, immunoprecipitation of radiolabeled proteins showed that cultured horse conceptuses secreted IGFBP3 into the culture medium. Endometrial samples from mares also contained IGFBP3 mRNA and protein; but there was no evidence of secretion of IGFBP3 into the uterine lumen by ligand blot analysis, and there was evidence of only very small amounts by Western blot analysis. These results indicate that the horse conceptus secretes significant quantities of IGFBP3 toward the conceptus capsule from as early as Day 10 after ovulation. Thus, most of the IGFBP3 contained within the capsule, which binds IGF-I to this special extracellular matrix of the preimplantation horse conceptus, is likely to be embryonic in origin. IGFBP3 in the horse conceptus capsule may enhance or modulate the action of IGFs on the developing conceptus.

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 P19 fusion protein. The antiserum raised against the C-terminal peptide recognized P19 on Western blots of denatured uterine secretions (subjected to SDS-PAGE), but it did not bind to the protein in tissue sections. However, the antiserum raised against the recombinant-derived fusion protein recognized P19 both on Western blots and in histological sections. Western blot analysis of tissues and fluids collected from early-pregnant mares demonstrated significant quantities of P19 in the endometrium and uterine secretions and in the embryonic capsule, the chorion, and the yolk sac fluid, showing that the protein is transferred through to the developing embryo. Concentrations of immunoreactive P19 declined during gestation so that, by Day 30, it had virtually disappeared from both maternal and fetal tissues and fluids. Immunohistochemical staining of endometrial biopsies collected during early pregnancy localized P19 to the glandular and luminal epithelia and to the lumina of the endometrial glands. The capsule and the trophoblast layer of the chorion from early (Days 16-17) horse conceptuses also stained positively with localization of P19 to the apical surface of the trophoblast cells. There was no detectable staining either in or on the embryonic disc. The presence of P19 in both the trophoblast layer and the yolk sac fluid suggests that P19 passes into the yolk sac fluid via trophoblast cells.

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 macrophages. The epithelial cells of the gland duct were similar to the surface epithelium, except that the nonciliated cells lacked secretory vesicles in the non ciliated cells. This glandular epithelium presented clear signs of secretory activity with conspicuous secretory vesicles holding electron-dense granula in the adluminal cytoplasm and a well developed supranuclear Golgi apparatus. Secretory products as well as cell debris were commonly found in the lumen of the glands. No clear signs of apocrine secretion were found and it seemed therefore, that the mechanism of secretion is merocrine, i.e. by exocytosis. The endometrial oedema and intense secretory activity, both under oestrogenic influence, contribute to the building up of the uterine fluid during oestrus. No differences in morphology of the secretory endometrium could be noticed between nulliparous mares and mares that had had 1 or 2 foals.

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 mares, 55%); (c) fluid accumulation in the uterine lumen (28 mares, 32%). A few mares had transluminal adhesions (7 mares, 8%) and in 2 mares the adhesions appeared to obstruct one uterine horn completely. A solitary discrete lump was detected in the wall of the uterine body in one mare and the suspicion of it being a leiomyoma was confirmed histologically with the aid of a visually directed biopsy sample. Free intraluminal structures were present in the uterine lumen in 3 mares, including one inspissated blood clot and two suspected remnants of resorbing pregnancies. Flexible biopsy forceps and scissors passed through the working channel of the endoscope were used to sever small thin adhesions, but this method proved inadequate for multiple adhesions or cysts. Solitary endometrial cysts were removed by means of conventional rigid biopsy forceps passed alongside the endoscope, although bleeding from the operation site usually limited this type of intervention.

Videoendoscopic evaluation of the mare's uterus: III. Findings in the pregnant mare

During a 5-year period 65 Pony and 20 Thoroughbred pregnant mares were subjected to videoendoscopic hysteroscopy from 10 to 266 days of gestation. The aims of these examinations were to 1) observe foetal and placental development in vivo (60 Pony and 10 Thoroughbred mares); 2) eliminate one of unicornuate twin conceptuses (9 Thoroughbred mares); 3) recover embryonic foetal and placental tissues non-surgically for experimental purposes (47 Pony mares); 4) induce focal separation of the placenta in late gestation as an experimental model of placentitis (5 pony mares and 1 Thoroughbred mare). It was possible to view the embryo and all constituent extra-embryonic membranes of the conceptus between Days 10 and 87 of gestation without having to perforate the allantochorion. This allowed study of physiological processes such as the coordinated uterine contractions responsible for conceptus motility between Days 7 and 17, active foetal movements, which began as early as Day 34, and invasion of chorionic girdle cells into the endometrium, which occurred between Days 34 and 38. From Day 90, vision of the foetus was reduced or prevented by the increased thickness of the allantochorion. Transendoscopic recovery of the conceptus was successful in all of 10 mares under 30 days of gestation, whereas only 10 of 18 attempts between Days 30 and 45 produced the conceptus without resorting to uterine lavage after initial rupture of the allantochorion. All 9 attempts to eliminate one of unilateral twin conceptuses were unsuccessful and the technique was abandoned as clinically unsuitable. Nevertheless, 9 of 22 (41%) single conceptuses remained viable after one or more hysteroscopic examinations.(ABSTRACT TRUNCATED AT 250 WORDS)