Developmental biology in horses involves the study of the processes by which horses grow and develop from a single fertilized egg into a fully formed organism. This field encompasses various stages, including embryonic development, fetal growth, and postnatal maturation. Researchers in this area examine cellular differentiation, gene expression, and morphogenetic movements that contribute to the formation of tissues and organs in equine species. Key topics include the molecular mechanisms that regulate developmental pathways, the influence of genetic and environmental factors on development, and the identification of developmental disorders. This page compiles peer-reviewed research studies and scholarly articles that explore the fundamental aspects of equine developmental biology, offering insights into the mechanisms driving normal and abnormal development in horses.
Saito S, Sawai K, Minamihashi A, Ugai H, Murata T, Yokoyama KK.We describe here the isolation and maintenance of pluripotent embryonic stem (ES) cells from equine blastocysts that have been frozen and thawed. Equine ES cells appear to maintain a normal diploid karyotype in culture. These cells express markers that are characteristic of mouse ES cells, namely, alkaline phosphatase, stage-specific-embryonic antigen 1, STAT3, and Oct4. We also describe protocols for the induction of differentiation in vitro to neural precursor cells in the presence of basic fibroblast growth factor (bFGF), epidermal growth factor, and platelet-derived growth factor and to he...
Semevolos SA, Nixon AJ, Fortier LA, Strassheim ML, Haupt J.The purpose of this study was to determine changes in the expression of regulatory molecules in normal equine articular cartilage throughout development up to 18 months of age. The hypothesis was that expression of these regulatory molecules would decrease from birth to postpubescence. Cartilage was harvested from normal femoropatellar or scapulohumeral joints from 34 fresh horse cadavers. Horses were placed in four age groups [prenatal (n = 5); prepubertal, 0-6 months (n = 11); pubertal, 7-14 months (n = 13); and postpubertal, 15-18 months (n = 5)]. Indian hedgehog (Ihh), Gli1, Gli3, Patched1...
Hinrichs K, Choi YH, Love CC, Chung YG, Varner DD.We evaluated the effects of different donor cell treatments and activation methods on production of blastocysts after equine nuclear transfer. Nuclear transfer was performed by direct injection of donor cells, using a piezo drill, and standard activation was by injection of sperm factor followed by culture with 6-dimethylaminopurine. There was no difference in blastocyst development between embryos produced with roscovitine-treated or confluent donor cells (3.6% for either treatment). Addition of injection of roscovitine or culture with cycloheximide at the time of activation did not affect bl...
Rathi R, Honaramooz A, Zeng W, Turner R, Dobrinski I.Grafting of testis tissue from immature animals to immunodeficient mice results in complete spermatogenesis, albeit with varying efficiency in different species. The objectives of this study were to investigate if grafting of horse testis tissue would result in spermatogenesis, and to assess the effect of exogenous gonadotropins on xenograft development. Small fragments of testis tissue from 7 colts (2 week to 4 years of age) were grafted under the back skin of castrated male immunodeficient mice. For 2 donor animals, half of the mice were treated with gonadotropins. Xenografts were analyzed a...
Nogueira GP, Barnabe RC, Verreschi IT.We measured progesterone and estradiol levels from birth to the beginning of adult life in 10 Thoroughbred fillies from the Equilia Stud Farm in Avaré SP, Brasil. The animals were measured and weighed monthly for the determination of body development and of a possible correlation between the rate of weight and height gain and the onset of detectable sex hormone levels. Jugular blood was collected twice a week and stored at -20 degrees C until assay of progesterone by a solid phase RIA with a sensitivity of 0.32 nmol L and of estradiol by liquid phase RIA adapted to low levels (3.67 pmol L ). ...
Choi YH, Love LB, Varner DD, Hinrichs K.This study was conducted to evaluate the in vitro development of equine oocytes with compact cumuli that had been subjected to a period of meiotic suppression with roscovitine before in vitro maturation. In experiment 1, oocytes were recovered from slaughterhouse-derived ovaries and held in M199 + 10% fetal bovine serum containing 66 microM roscovitine with or without an overlay of mineral oil in 5% CO2 in air at 38.2 degrees C for 16-18 or 24 h. No oocytes treated with roscovitine in the absence of an oil overlay for 16-18 h were maturing, compared with 2-4% of oocytes in other treatments. In...
Parlevliet JM, Pearl CA, Hess MF, Famula TR, Roser JF.The presence of steroids and their receptors throughout development, specifically androgen receptor (AR), estrogen receptor alpha (ERalpha) and estrogen receptor beta (ERbeta), in the epididymis of a high estrogen producing species like the stallion has not been determined. Epididymal and testicular samples were collected for analysis of testosterone and estradiol-17beta (E(2)) concentrations and for immunolocalization of AR, ERalpha and ERbeta. The concentration of testosterone in the testis and epididymis were not different among age groups (P>0.05). AR was localized in the principal cell...
Abd-Elnaeim MM, Leiser R, Wilsher S, Allen WR.This investigation was carried out to study the equine placenta from early gestation to near term, with special reference to morphological changes associated with the development of the vasculature of the fetal component of the microcotyledons. Pregnant uteri were removed post mortem from five Thoroughbred mares between 110 and 309 days of gestation, two of which were aged, multiparous animals suffering age-related degenerative changes in their endometrium (endometrosis), while the other three were young, and had primigravid normal healthy uteri. Pieces of endometrium with placenta attached we...
Arai KY, Tanaka Y, Taniyama H, Tsunoda N, Nambo Y, Nagamine N, Watanabe G, Taya K.In this study, the expression patterns of inhibins, activins, insulin-like growth factor-I (IGF-I) and steroidogenic enzymes in equine placentae recovered during the latter two-thirds of gestation were examined. Concentrations of inhibin A and inhibin pro-alphaC in endometrial and fetal placental tissue homogenates were very low during the period examined, whereas these tissues contained high concentrations of activin A. In both maternal endometrial and fetal placental tissues, activin A levels decreased as pregnancy progressed. Expression of inhibin alpha-subunit was not observed in the place...
Lagutina I, Lazzari G, Duchi R, Colleoni S, Ponderato N, Turini P, Crotti G, Galli C.The objective of the present work was to investigate and clarify the factors affecting the efficiency of somatic cell nuclear transfer (NT) in the horse, including embryo reconstruction, in vitro culture to the blastocyst stage, embryo transfer, pregnancy monitoring and production of offspring. Matured oocytes, with zona pellucida or after zona removal, were fused to cumulus cells, granulosa cells, and fetal and adult fibroblasts, and fused couplets were cultured in vitro. Blastocyst development to Day 8 varied significantly among donor cells (from 1.3% to 16%, P < 0.05). In total, 137 nuclear...
Choi YH, Love CC, Varner DD, Hinrichs K.This study was conducted to evaluate the effects of thawing, division into aliquots and refreezing on fertilizing capacity (ability to support embryo development after intracytoplasmic sperm injection; ICSI) of frozen stallion semen. Frozen semen from a fertile stallion was thawed, diluted 1:100 with freezing extender, and refrozen (2F treatment). Control semen was frozen only once. In vitro matured equine oocytes were injected with: (1) motile control spermatozoa; (2) motile 2F spermatozoa; (3) non-motile 2F spermatozoa; or (4) non-motile 2F spermatozoa, followed by injection of sperm extract...
O'Connor SJ, Gardner DS, Ousey JC, Holdstock N, Rossdale P, Edwards CM, Fowden AL, Giussani DA.The aims of this study were to compare and contrast the development of the cardiac baroreflex and endocrine responses to acute hypotensive stress in healthy newborn pony foals and lambs during the first two weeks of postnatal life. Methods: Under general anaesthesia, seven Welsh pony foals and six Welsh Mountain lambs were catheterised with hind limb artery and vein catheters. Following post-surgical recovery, at 1 week and 2 weeks of age, blood pressures of the animals were raised and lowered acutely by intravenous infusion of phenylephrine and sodium nitroprusside, respectively. During hypot...
Yamano S, Eto D, Kasashima Y, Hiraga A, Sugiura T, Miyata H.To determine the growth-related changes in metabolic and anatomic properties in equine muscle fiber type, including hybrid fibers identified with immunohistochemical analysis. Methods: 24 2-, 6-, 12-, and 24-month-old female Thoroughbreds. Methods: Samples were obtained from the gluteus medius muscle of all horses. Expression of myosin heavy chain (MHC) isoforms MHC-I, -IIa, -IIb, and -IIx in each muscle fiber was detected by use of 4 primary monoclonal antibodies: BA-D5, SC-71, BF-F3, and BF-35, respectively. Five muscle fiber types (types I, I/IIA, IIA, IIA/IIX, and IIX) were immunohistochem...
Eldridge-Panuska WD, di Brienza VC, Seidel GE, Squires EL, Carnevale EM.Experiments were conducted to determine viability of equine embryos in vivo after vitrification. In a preliminary study (Experiment 1), embryos were exposed in three steps to vitrification solutions containing increasing concentrations of ethylene glycol and glycerol (EG/G); the final vitrification solution was 3.4 M glycerol + 4.6 M ethylene glycol in a base medium of phosphate-buffered saline. Embryos were warmed in a two-step dilution and transferred into uteri of recipients. No pregnancies were observed after transfer of blastocysts >300 microm (n = 3). Transfer of morulae or blastocyst...
Hinrichs K, Choi YH, Love LB, Varner DD, Love CC, Walckenaer BE.We evaluated the relationship of initial chromatin configuration to time of oocyte recovery and to nuclear maturation after culture in horse oocytes having compact (Cp) and expanded (Ex) cumuli. In addition, we evaluated the effect of oocyte type, time of recovery, and duration of culture on blastocyst development after intracytoplasmic sperm injection. In oocytes collected within 1 h of slaughter, fibrillar and intermediate chromatin configurations were more prevalent in Cp than in Ex oocytes (68% and 12%, respectively). In Cp oocytes collected after a 5- to 9-h delay, the proportions in the ...
Lindsay DS, Mitchell SM, Vianna MC, Dubey JP.Equine protozoal myeloencephalitis is a major cause of neurological disease in horses from the Americas. Horses are considered accidental intermediate hosts. The structure of sporocysts of the causative agent, Sarcocystis neurona, has never been described. Sporocysts of S. neurona were obtained from the intestines of a laboratory-raised opossum fed skeletal muscles from a raccoon that had been fed sporocysts. Sporocysts were 11.3 by 8.2 microm and contained 4 sporozoites. The appearance of the sporocyst residuum was variable. The residuum of some sporocysts was composed of many dispersed granu...
Fintl C, Pearson GT, Ricketts SW, Mayhew IG, Hudson NP.This study set out to determine the pattern of development and distribution of the interstitial cells of Cajal (ICC) in the intestinal tract of the equine fetus and neonate. Intestinal tissue samples from 12 naturally aborted equine fetuses and three euthanized neonates were collected and fixed in formalin prior to applying standard immunohistochemical labelling techniques targeting the c-Kit protein of the ICC. At 6 months of gestation, a network of ICC was present in the myenteric plexus region of both the small and the large intestine. ICC were also present within the circular muscle layer....
Choi YH, Love LB, Varner DD, Hinrichs K.This study was conducted to evaluate the effect of initial cumulus morphology (expanded or compact) and duration of in vitro maturation (24, 30 or 42 h) on the developmental competence of equine oocytes after intracytoplasmic sperm injection (ICSI). The effect of manipulation temperature (room temperature vs 37 degrees C) at the time of ICSI and concentration of glucose (0.55 vs 5.5 mM) during embryo culture was also investigated. The nuclear maturation rates of expanded (Ex) oocytes were significantly (P < 0.001) higher than those of compact (Cp) oocytes at all maturation times (61-72 vs 23-2...
Allen WR, Wilsher S, Tiplady C, Butterfield RM.The growth parameters exhibited by seven Thoroughbred (Tb) foals that had experienced a 'restricted' in utero existence following transfer as embryos to the uteri of smaller Pony (P) mares (Tb-in-P) and, conversely, six P foals that experienced a 'luxurious' in utero existence after transfer to larger Tb mares (P-in-Tb), were compared from birth to 3 years of age with those exhibited by six normal Tb-in-Tb and six P-in-P foals conceived by within-breed artificial insemination. Bodyweight, height at the withers, girth, poll-to-nose length, crown-rump length and three foreleg longbone measuremen...
Bragulla H.Fetal development of the unique papillary body and its localized peculiarities in the equine hoof are described based on the study of 51 fetuses, nine newborn foals, and five adult horses. The shape and dimensions of the dermal papillae and lamellae have a formative influence on the structure and physical quality of the corneous hoof capsule with its horn tubules and lamellae. The size and arrangement of these horn structures determine the mechanical quality of hoof horn. Proper horn quality is a prerequisite for the various functions of the hoof capsule, such as protecting the living dermis s...
Choi YH, Love LB, Westhusin ME, Hinrichs K.Early development of embryos produced by transfer of equine nuclei to bovine cytoplasts is superior to that of intraspecies equine nuclear transfer embryos. This may be related to differences in chromatin remodeling or efficiency of activation between the two oocyte types. The pattern of donor nucleus remodeling was examined in equine-equine and equine-bovine reconstructed oocytes. Chromosome condensation occurred in equine cytoplasts by 2 h but was not seen in bovine cytoplasts until 4 h. We investigated the effect of activation of equine-equine reconstructed oocytes at <30 min or at 2 h a...
Gurfield N, Benirschke K.The placenta from a 300-day-gestational age, female, Arabian equine fetus was examined. Multifocal to coalescing, 0.5- to 4-cm-diameter, white, smooth nodules covered 50% of the placenta. Microscopic evaluation of the nodules revealed undifferentiated germ cells and a haphazard arrangement of immature, mesenchymal stroma, cartilage, squamous cornifying epithelium, scattered ducts and secretory acini lined by cuboidal to columnar epithelium, and mineralized foci. No umbilicus, arrangement about an axial skeleton, or organized polarity of structures was present. The lesion was diagnosed as a pla...
Bragulla H, Hirschberg RM.Accessory organs of the integument are locally modified parts of the potentially feather-bearing skin in birds (e.g., the rhamphotheca, claws, or scales), and of the potentially hairy skin in mammals (e.g., the rhinarium, nails, claws, or hooves). These special parts of the integument are characterised by a modified structure of their epidermal, dermal and subcutaneous layers. The developmental processes of these various integumentary structures in birds and mammals show both similarities and differences. For example, the development of the specialised epidermal structures of both feathers and...
Tremoleda JL, Stout TA, Lagutina I, Lazzari G, Bevers MM, Colenbrander B, Galli C.Blastocyst formation rates during horse embryo in vitro production (IVP) are disappointing, and embryos that blastulate in culture fail to produce the characteristic and vital glycoprotein capsule. The aim of this study was to evaluate the impact of IVP on horse embryo development and capsule formation. IVP embryos were produced by intracytoplasmic sperm injection of in vitro matured oocytes and either culture in synthetic oviduct fluid (SOF) or temporary transfer to the oviduct of a ewe. Control embryos were flushed from the uterus of mares 6-9 days after ovulation. Embryo morphology was eval...
Dongus H, Beelitz P, Schöl H.The female reproductive system of Thelazia lacrymalis (Nematoda: Thelaziidae) was investigated by light and scanning electron microscopy (SEM) with regard to the developmental stages and the stage deposited by the gravid nematode. Female T. lacrymalis have a didelphic and opisthodelphic type of reproductive system with paired ovaries, oviducts and uteri and a single vagina and vulva. Round and spindle-shaped primary oocytes are documented within the ovaries and oviducts, respectively. The distal part of each uterus provides a fertilization chamber filled with spermatozoa, followed by a sphinct...
Hoffer MA, Leach DH, Doige CE.The navicular bone, navicular bursa and their associated structures were collected from 20 horses ranging in age from 80 days gestation to 2 years post-gestation. The right front foot of every horse was sampled for light microscopy. The development of the navicular bursa and associated structures were studied. Study of the developmental anatomy of the equine navicular bursa established that the bursa is a distinct entity in both the fetus and the adult horse. Development of the bursal cavity in the fetus was found to be complete by 120 days of gestation. Synovial membrane of the navicular burs...
Carnevale EM, Maclellan LJ, Stokes JAE.Establishment of optimal methods for equine embryo culture has been slow when compared to some domestic species. In part, this delay was caused by the failure of standard in vitro fertilization techniques in horses. However, the development of intracytoplasmic sperm injection (ICSI) for the assisted fertilization of equine oocytes has resulted in a renewed interest in establishing optimal methods for embryo culture. Currently, ICSI-produced equine embryos are cultured using media designed for other species or other cell cultures and, typically, with the addition of serum. Although systems spec...
Carter AM.Recently a fossil of one of the earliest jawed fishes was found with a fetal skeleton and the remains of a cord. It was from the Devonian period and takes the history of vertebrate placentation back to 380 million years ago. This and later fossil evidence for viviparity in marine reptiles and early mammals is reviewed. Of particular interest are the fossils of horses as they document that a reproductive strategy with a single precocial newborn was evolved early on. In one instance there is sufficient representation of soft tissue to imply that early horses had a diffuse placenta, much as had b...
Flores Bragulat AP, Ortiz I, Catalán J, Dorado J, Hidalgo M, Losinno L, Dordas-Perpinyà M, Yánez-Ortiz I, Martínez-Rodero I, Miró J, Gambini A.Equus members exhibit very divergent karyotype, genetic plasticity, and significant differences in their reproductive physiology. Despite the fact that somatic cell nuclear transfer and intracytoplasmic sperm injection (ICSI) has gained relevance in the last few years in horses, few reports have been published exploring ovum pick up (OPU) and in vitro maturation (IVM) of cumulus-oocyte complexes (COCs) in donkeys. Yet, some donkey species and breeds are considered endangered, and these assisted-reproductive technologies could help to preserve the genetic of valuable individuals. In this study...
Curran S, Urven L, Ginther OJ.Eighteen equine embryos, 3 each on Days 20, 22, 24, 26, 28 and 30 post ovulation, were collected transcervically by uterine lavage, fixed in 4% paraformaldehyde and embedded in paraffin wax. Ten micron serial sections were stained to determine alkaline phosphatase (AP) activity in the cells. Positive cells were counted and their approximate location determined. The cells were approximately 8 microm in diameter and the entire cell, except the nucleus, stained strongly with many small round areas of intense staining in the cytoplasm. The cells varied from round to elongated in shape and pseudopo...
Fintl C, Pearson GT, Ricketts SW, Mayhew IG, Hudson NP.This study set out to determine the pattern of development and distribution of the interstitial cells of Cajal (ICC) in the intestinal tract of the equine fetus and neonate. Intestinal tissue samples from 12 naturally aborted equine fetuses and three euthanized neonates were collected and fixed in formalin prior to applying standard immunohistochemical labelling techniques targeting the c-Kit protein of the ICC. At 6 months of gestation, a network of ICC was present in the myenteric plexus region of both the small and the large intestine. ICC were also present within the circular muscle layer....
Young M, Allen WR, Deutz NE.Free amino-acid concentrations were measured in maternal venous and fetal umbilical vein plasma, and in the allantochorion, of Thoroughbred mares at term. Concentrations in maternal and fetal plasma were similar to those reported previously in equids. The concentrations of free amino-acids in the allantochorion were higher than those in the maternal and fetal plasmas and were characterised by high levels of the nonessential amino-acids as observed in other species. Fourteen of the 20 amino-acids measured had similar allantochorion/umbilical vein concentration ratios suggesting that simple grad...
Abd-Elnaeim MM, Derar IR, Wilsher S, Allen WR, Leiser R, Schuler G.The functions of placental oestrogens during equine pregnancy are still unclear. Yet, they may act predominantly as local regulators of growth and differentiation in the microplacentomes. Thus, expression patterns of oestrogen receptors (ERs) alpha and beta were investigated in the microcotyledonary placenta from pregnant mares at 110, 121, 179, 199 and 309 days of gestation by immunohistochemistry. In microplacentomes, both the ER isoforms were detected in trophoblast (T) cells, chorionic villous stroma (FS), microcaruncular epithelium (ME) and microcaruncular stroma (MS). Proportions of posi...
Jenner F, van Osch GJ, Weninger W, Geyer S, Stout T, van Weeren R, Brama P.Articular cartilage regeneration is the focus and goal of considerable research effort. Since articular chondrocytes descend from a distinct cohort of progenitor cells located in embryonic nascent joints (interzones), establishing the timing of equine interzone formation is an essential first step towards understanding equine joint and articular cartilage development. Objective: To establish the time frame during which the equine femorotibial interzone forms. Methods: Descriptive anatomical study. Methods: Equine embryos were harvested at 37 (E37), 40, 42, 45, 50 and 65 days' gestation. The fe...
Vanderwall DK.Tremendous progress has been made in the development of assisted reproductive techniques that may enhance the reproductive efficiency of the horse. However, techniques that involve the manipulation of oocytes and/or embryos may themselves be detrimental to embryo viability and subsequent development. Therefore, an objective method of assessing viability of embryos before and/or after oocyte/embryo manipulation is desirable. At this time, morphologic evaluation is the most widely used method of determining the viability of equine embryos. Although morphologic assessment of embryo quality will n...
Sisken BF, Zwick M, Hyde JF, Cottrill CM.This review covers the development and maturation of the cerebellum of the horse and compares this developmental sequence with that of man, mouse and chicken. These comparisons attempt to correlate morphological and neurochemical features, developmental time and functional performance necessary for survival at birth. Although there is great disparity between these 3 species, the basic anatomical structures of the cerebellum are present as are specific cellular groups, synapses and neurochemical markers. In addition to this structural homogeneity, other attributes of the cerebellum are its easi...
Pruitt JA, Forrest DW, Burghardt RC, Evans JW, Kraemer DC.The viability and ultrastructure of equine embryos were assessed following culture in a static or perifusion system. The percentage change in diameter was greater (P less than 0.025) for embryos in the static treatment (71%) than in the perifusion treatment (33%). Fluorescein diacetate (FD) scores, the percentage of fluorescing cells (FC) and fluorescent intensity (FI), also were greater (P less than 0.05 and P less than 0.01) following static culture than for embryos cultured in the perifusion system. Four of 9 control embryos resulted in pregnancies but no embryos cultured in either system p...
Younis AI, Sehgal PK, Biggers JD.A single s.c. injection of 1000 IU of pregnant mare's serum gonadotrophin (PMSG) stimulates the growth of multiple antral follicles in cynomolgus monkeys (Macaca fascicularis). The number of cumulus-enclosed oocytes (CEO) from six non-stimulated controls was 36 (mean = 6). In contrast, a total of 95 CEO (mean = 31.7) were recovered from three animals stimulated and ovariectomized 3 days later, while 385 CEO (mean = 128.3) were obtained from three animals stimulated and ovariectomized 4 days later. A comparison of the effects of highly purified human follicle-stimulating hormone (FSH), human lu...
Choi YH, Love LB, Varner DD, Hinrichs K.This study was conducted to evaluate the effect of initial cumulus morphology (expanded or compact) and duration of in vitro maturation (24, 30 or 42 h) on the developmental competence of equine oocytes after intracytoplasmic sperm injection (ICSI). The effect of manipulation temperature (room temperature vs 37 degrees C) at the time of ICSI and concentration of glucose (0.55 vs 5.5 mM) during embryo culture was also investigated. The nuclear maturation rates of expanded (Ex) oocytes were significantly (P < 0.001) higher than those of compact (Cp) oocytes at all maturation times (61-72 vs 23-2...
Macdonald AA, Chavatte P, Fowden AL.Scanning electron microscopy was used to examine the microstructure of the maternal and fetal placenta from 25 pregnant ponies (Equus caballus) throughout the second half of gestation. Samples of placenta, 2-6 cm(2)in area, were collected from the antimesometrial region of the pregnant horn at 105 days (n=1), 165-219 days (n=5), 260 days (n=3), 270-277 days (n=3), 313-337 days (n=11) and immediately after spontaneous delivery at term (n=2). The maternal microcaruncle appears to be created from a clustering of about 16 uterine crypts encapsulated in a connective tissue sheath. There is a gestat...
Wilsher S, Gower S, Allen WR.Previous reports documenting progesterone receptors (PR) and oestrogen receptors (ER) in the endometrium of early pregnant mares included specimens only up to Day 20 post ovulation. This study aimed to localise PR and ERα on equine feto-maternal tissues between Days 20 and 68 to encompass the period around fixation of the conceptus, development of the endometrial cups and attachment and initial interdigitation of the allantochorion. During early pregnancy mares had the same pattern of PR in the endometrium as that reported for other mammals; namely, a loss of PR from the endometrial epithelia...
Antczak DF, Allen WR.There is little evidence for maternal immunological recognition of pregnancy in most species with the striking exception of the members of the genus Equus. Almost all mares make strong cytotoxic antibody responses to paternally inherited fetal antigens by Day 60 of gestation. Most of these responses are directed against antigens of the Major Histocompatibility Complex (MHC), which constitutes the primary immunogenetic barrier to successful organ transplantation. The source of fetal MHC antigens in the pregnant mare appears to be the specialized trophoblast cells of the chorionic girdle region ...
Jones CJ, Wooding FB, Dantzer V, Leiser R, Stoddart RW.The glycosylation of the equine interhaemal barrier and areola was studied throughout the period of gestation. Placentae of 35, 37, 50, 119, 152, 200, 280 and 300 days gestation were investigated, using semithin plastic embedded sections and a panel of 15 biotinylated lectins with an avidin-peroxidase revealing system. Glycosylation of the trophoblast and maternal epithelium showed the most change during the first 50 days of gestation, being associated with the initial stages of adhesion and attachment. In the trophoblast, non-bisected tri/tetraantennary complex N-glycan was only evident after...
Choi YH, Chung YG, Walker SC, Westhusin ME, Hinrichs K.This study was conducted to evaluate the effects of insulin-like growth factor I (IGF-I) and other media factors during oocyte maturation, and the presence of different compositions of amino acids in embryo culture medium, on the development of equine embryos. Oocytes recovered from slaughterhouse-derived ovaries were matured in vitro for 24 h and those with a polar body were subjected to intracytoplasmic sperm injection (ICSI) or nuclear transfer with adult fibroblasts (NT). For ICSI embryos, there were no significant differences in rates of morphological cleavage, cleavage with normal nuclei...
Rose BV, Cabrera-Sharp V, Firth MJ, Barrelet FE, Bate S, Cameron IJ, Crabtree JR, Crowhurst J, McGladdery AJ, Neal H, Pynn J, Pynn OD, Smith C....Early pregnancy loss occurs in 6-10% of equine pregnancies making it the main cause of reproductive wastage. Despite this, reasons for the losses are known in only 16% of cases. Lack of viable conceptus material has inhibited investigations of many potential genetic and pathological causes. We present a method for isolating and culturing placental cells from failed early equine pregnancies. Trophoblast cells from 18/30 (60%) failed equine pregnancies of gestational ages 14-65 days were successfully cultured in three different media, with the greatest growth achieved for cells cultured in Amnio...
Walter I, Tschulenk W, Budik S, Aurich C.The present study gives a detailed ultrastructural description of equine conceptuses at Day 14 (n = 2) and Day 16 (n = 3) after ovulation. Whereas on Day 14 only primitive structures were seen, on Day 16 neurulation and formation of mesodermal somites had taken place. The ectoderm of the embryo itself and the surrounding trophoblast ectodermal cells were characterised by specific cell surface differentiations. At the embryonic ectodermal cell surface (14 and 16 days) remarkable protruded and fused cytoplasmic projections were seen, typically associated with macropinocytotic events involved in ...
Raeside JI, Christie HL, Waelchli RO, Betteridge KJ.The embryo proper in early equine pregnancy has recently been shown to have a remarkable capacity for metabolism of oestrogens. High concentrations of oestrogens in yolk-sac fluid could provide substrate for local metabolism in tissues of the embryo proper and this activity could have significance for early development. Due to the high level of oestrogen metabolism in the embryo proper we examined the possibility that it could also biosynthesise oestrogens. Conceptuses were collected in the fourth week of pregnancy (n=23) and the embryo was separated from extraembryonic tissues for incubation ...
Rijkenhuizen AB, Németh F, Dik KJ, Goedegebuure SA.A macroscopic, arteriographic and histological study of the development and the arterial anatomy of the navicular bone of 33 foetuses and 55 young horses is described. After 125 days of gestation the blood supply consists of two routes: one situated in the superficial layer of the fibrocartilage and the other similar to the blood supply of the navicular bone of the normal mature horse. After 270 days gestation, the blood vessels in the fibrocartilage gradually regressed and retracted until they have disappeared at six months after birth. At two months after birth the first macroscopic thinning...
Shilton CA, Kahler A, Roach JM, Raudsepp T, de Mestre AM.Embryonic and foetal loss remain one of the greatest challenges in equine reproductive health with 5-10% of established day 15 pregnancies and a further 5-10% of day 70 pregnancies failing to produce a viable foal. The underlying reason for these losses is variable but ultimately most cases will be attributed to pathologies of the environment of the developing embryo and later foetus, or a defect intrinsic to the embryo itself that leads to lethality at any stage of gestation right up to birth. Historically, much research has focused on the maternal endometrium, endocrine and immune responses ...
Robles M, Peugnet PM, Valentino SA, Dubois C, Dahirel M, Aubrière MC, Reigner F, Serteyn D, Wimel L, Tarrade A, Chavatte-Palmer P.Ponies and sometimes draft horses are often used as experimental models for horses although size and metabolic parameters are known to vary between horse breeds. So far, there is little information about differences of placental structure and no information about differences of placental function between breeds. The aim of this study was to investigate differences in placental size, structure and function at birth in relation to foal size and weight in ponies, Saddlebred and draft horses. Pony, Saddlebred and draft horse pregnancies were obtained by artificial insemination over 2 successive br...
Gerstenberg C, Allen WR.Branched tubular endometrial glands are key features of the uterine lining in mares. The epithelium in the neck regions of the glands is similar to that lining the lumen of the uterus, whereas the epithelium in the deeper, coiled portions of the glands secretes protein rich histotrophe or 'uterine milk' during dioestrus and pregnancy. The present study was performed to characterize endometrial histology in perinatal and peripubertal fillies and to investigate the influences of specific steroid treatments on endometrial gland development in the prepubertal period. Uteri obtained from equine fet...
Wilsher S, Lefranc AC, Allen WR.During embryo transfer (ET) the equine embryo can tolerate a wide degree of negative asynchrony but positive asynchrony of >2 days usually results in embryonic death. There is still confusion over whether this is due to the inability of the embryo to induce luteostasis or to an inappropriate uterine environment. Objective: To assess embryo survival and development in an advanced uterine environment. Objective: Embryo-uterine asynchrony, not the embryo's inability to induce luteostasis, is responsible for embryonic death in recipient mares with a >2 days chronologically advanced uterus. Methods...
Crowell-Davis SL.Examination of the developmental changes that occur in the behavior of foals reveals three major periods that can be characterized by certain types of behavior. Although the beginnings and endings of these periods are not definitive, these periods may be conceptually useful in evaluating a foal's behavior. Period of Dependence. During the first 4 weeks of life, a foal is maximally dependent on its mother for sustenance, remains near her, and has little contact with other horses or ponies of any age. Period of Socialization. During the second and third months of life, foals have rapidly increas...
Smits K, Goossens K, Van Soom A, Govaere J, Hoogewijs M, Peelman LJ.In vitro-produced (IVP) equine blastocysts can give rise to successful pregnancies, but their morphology and developmental rate differ from those of in vivo-derived equine blastocysts. The aim of the present study was to evaluate this difference at the genetic level. Suppression subtractive hybridisation (SSH) was used to construct a cDNA library enriched for transcripts preferentially expressed in in vivo-derived equine blastocysts compared with IVP blastocysts. Of the 62 different genes identified in this way, six genes involved in embryonic development (BEX2, FABP3, HSP90AA1, MOBKL3, MCM7 a...
