bluuebunny/crossref_metadata_2025_split huggingface dataset:
Maturation of the central nervous system: comparison of equine and other species
Authors: SISKEN BETTY F. , ZWICK M. , HYDE J. F. , COTTRILL CAROL M. 
Published: June 2010

SummaryThis 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 easily identified cellular populations and its well ordered pattern of growth and differentiation.The cerebella of the developing chick and mouse have been studied in great detail as they are amenable to experimental manipulations. The pattern of cellular differentiation appears to be reproducible from specles to species and differs primarily as it relates to gestational age and functional requirements at birth. For instance, most of the large neurones of the cerebellar cortex differentiate early with small neurones and neuroglia differentiating later. Neurogenesis of the cerebellar cortex is fairly complete in the newborn foal and chick hatchling, but not in the human or rodent newborn.
Foetal endocrine maturation
Authors: CHALLIS J. R. G. , BASSETT NICOLE , BERDUSCO E. T. M. , HAN V. K. M. , LU FENG , RILEY S. C. , YANG KAIPING 
Published: June 2010

SummaryIn domestic ruminants such as the sheep, birth is effected through sequential maturation of the foetal hypothalamic‐pituitary‐adrenal (HPA) axis, leading to the increased output of cortisol. Factors regulating foetal pituitary adrenocorticotrophin (ACTH) secretion have been delineated, and these include corticotrophin releasing hormone (CRH), arginine vasopressin, prostaglandin (PG) E2 and endogenous opioids. The pre‐partum increase in foetal plasma ACTH is associated with a rise in pro‐opiomelanocortin (POMC) mRNA in the foetal pars distalis, and with an altered pattern of POMC post‐translational processing. Foetal adrenal activation results from an increase in ACTH receptors and enhanced coupling through the Gs protein to adenylate cyclase, and increased expression of key steroidogenic enzymes including P450c17. Cortisol modulates the mechanism by which ACTH activates foetal adrenal function, through specific glucocorticoid receptors (GR) in the foetal adrenal cortex. Although the numbers of GR change with gestation, the relative abundance of GR mRNA does not, pointing to post‐translational regulatory mechanisms. Cortisol also stimulates an increase in the concentration of its own high affinity binding protein (corticosteroid binding globulin; CBG) in the foetal circulation, apparently by increasing CBG gene expression in the foetal liver, and by altering the extent of foetal CBG glycosylation in a manner that would be expected to decrease the metabolic clearance of this glycoprotein. Clear evidence for placental CRH and ACTH production is lacking in sheep, but PGE2, produced in increasing amounts by the placenta during late pregnancy, may augment the drive to HPA maturation. Aspects of the maturational pathway of cortisol biosynthesis have been described in other species, including the horse, and some comparison is made with the more detailed information currently available from species such as the sheep.
Retinol‐binding protein in equine endometrium
Authors: McDOWELL KAREN J. , ADAMS MARY H. , SMITH TRACI L. , BAKER C. B. 
Published: June 2010

SummaryIn Exp. 1, endometrial biopsies were collected from normally cycling, unmated mares at Days 0, 4, 8, 10, 12, 14 and 16 and from pregnant mares at Days 10, 12, 14 and 15 after ovulation (2 mares/day) and immediately frozen on solid CO2.In Exp. 2, biopsies were obtained from acyclic intact mares treated with steroids in regimens designed to simulate an oestrous cycle (oestrogen, low progesterone or high progesterone). Duplicate endometrial samples from each mare were frozen for RNA analysis or pooled within day and incubated in vitro for analysis of proteins secreted into the medium by 2‐D PAGE and fluorography. Fluorograms from all 3 groups revealed proteins with electrophoretic mobility consistent with RBP (Mr 21, 000–22, 000, pI 5–6.5) Identification of these proteins as immunoreactive RBP was confirmed by western blot analysis.Endometrium which had been frozen at the time of collection was pooled within day (Exp. 1) or within group (Exp. 2), and total RNA was extracted. Northern blot analysis revealed positive hybridisation for RBP at ˜0.9 kb in all samples.These results demonstrate the presence of mRNA for RBP in equine endometrium during the oestrous cycle and early pregnancy, that equine endometrium synthesises and secretes RBP, and that RBPmRNA and protein concentration may be influenced by the steroid environment. Endometrial RBP probably plays a critical role in successful development of the equine embryo and establishment of pregnancy.
The live foaling rate per cycle in mares
Authors: BAKER C. B. , LITTLE T. V. , McDOWELL KAREN J. 
Published: June 2010

SummaryThe overall live foaling percentage per cycle on 4 Kentucky Thoroughbred farms was 42.0%. The rate varied with mare reproductive status, mare age, cycle number and stallion. The most pronounced effect was associated with mare age. Estimates of the relative importance of embryonic loss as a factor limiting reproductive success for young and old mares. suggest that young mares lose half of their embryos from fertilisation to term, and the loss rate increases with mare age to the point that old mares lose all or nearly all of their embryos.
Age‐associated subfertility before entry of embryos into the uterus in mares
Authors: CARNEVALE E. M. , GRIFFIN P. G. , GINTHER O. J. 
Published: June 2010

SummaryAge‐associated changes in the fertility of pony mares were studied in 3 experiments. On Days 1.5 and 3 (Day 0=day of ovulation), respectively, the collection rate of ova (cleaved or uncleaved) per ovulation was significantly lower in old mares (>20 years; 11/20 and 6/9) than in young mares (2–10 years; 17/18 and 9/9). The percentage of cleaved ova was significantly lower for old mares (5/11) than for young mares (15/17) on Day 1.5 but was not different on Day 3. Embryos from old mares had significantly more morphological abnormalities and fewer embryonic cells on Day 3. The transfer of embryos from young or old donors into the oviducts of young or old recipients did not significantly alter embryo development between Days 1.5 and 3.5. On Day 11, significantly fewer pregnancies and smaller embryonic vesicles were present in old mares than in young mares. The pregnancy rate on Day 3 was not different from the pregnancy rate on Day 11 within old mares (6/9 versus 4/9) or within young mares (9/9 versus 8/9). The studies indicated that a high incidence of age‐associated defects occurred before the day that an embryo would be expected to enter the uterus.
Interaction between stallion spermatozoa and oviductal epithelial cells in vitro
Authors: LEFEBVRE R. , SAMPER J. C. 
Published: June 2010

SummaryOviducts were collected from oestrous, dioestrous and anoestrous mares at the abattoir, and the epithelial cells were incubated in tissue culture medium. Stage of the cycle did not appear to affect significantly the quality of the culture, the ability of sperm cells to attach to the oviduct or prolong the motility of bound spermatozoa. More fresh spermatozoa attached to oviductal tissue than did capacitated, acrosome‐reacted and frozen‐damaged spermatozoa, suggesting that sperm membrane integrity is one of the factors necessary for sperm attachment to the oviductal epithelial cells. Spermatozoa from subfertile stallions had a significantly lower attachment rate to oviductal tissue compared with those of a stallion with normal fertility.
Heparin‐induced capacitation: a comparison between the bull and stallion
Authors: FARLIN M. E. , JASKO D. J. , GRAHAM J. K. , SQUIRES E. L. 
Published: June 2010

SummarySpermatozoa were incubated with 0, 10, 50 or 100 μg heparin/ml for 4 h at 37°C (bull) or 39°C (stallion) in 5% CO2. Spermatozoa were then challenged with 10 μM‐calcium ionophore A23187 at 0, 2 and 4 h of incubation for an additional 30 min. Samples were evaluated for the % of motile and acrosome‐reacted spermatozoa. The spermatozoa of both species exhibited a decline in the % of motile spermatozoa during incubation over 4 h, and this decline was similar for heparin and non‐heparin‐treated stallion spermatozoa (P>0.05). Within incubation times the % of acrosome‐reacted stallion spermatozoa during incubation was similar (P<0.05) among heparin and non‐heparin‐treated spermatozoa. As for bull spermatozoa, addition of 10 μM‐A23187 to stallion spermatozoa induced more acrosome‐reactions in heparin‐treated than in non‐heparin‐treated spermatozoa (P<0.05). However, maximal inductions of acrosome reactions following ionophore challenge occurred in stallion spermatozoa after 4 h incubation with ≥50 μg heparin/ml. Bull and stallion spermatozoa incubated with heparin exhibited higher (P<0.05) % of acrosome‐reacted spermatozoa after challenge with A23187 than did non‐heparin‐incubated spermatozoa, suggesting that they may have undergone capacitation during incubation with heparin. Although incubation with 10 μg heparin/ml was sufficient to induce capacitation in bull spermatozoa, stallion spermatozoa required incubation with ≥50 μg heparin/ml.
Transmission electron microscopy of equine embryos cryopreserved by different methods
Authors: e ALVARENGA F. C. LANDIM , ALVARENGA M. A. , MEIRA C. 
Published: June 2010

SummaryHorse embryos were preserved with different cooling rates and cryoprotectants. Embryos in Groups I and II were treated with glycerol as cryoprotectant. In Group I the temperature was lowered at 2.5‐4°C/min until seeding (‐6 to ‐7°C) and at 0.3‐0.6°C/min until ‐30°C, followed by direct immersion in liquid nitrogen. Group II embryos were placed in a medium with 20% (v/v) glycerol plus 0.5 M‐sucrose. Cooling was in liquid nitrogen vapour (‐25°C) for 5 min, followed by immersion in liquid nitrogen. Group III embryos were cooled at the same rate as used for Group I, but the cryoprotectant was 1, 2‐propanediol. Group IV embryos were unfrozen. Embryo transfer was done non‐surgically just after thawing. Pregnancy rates were 40%, 0%, 0% and 80% in Groups I, II, III and IV, respectively. Group I embryos survived with most plasma and nuclear membrane intact. Embryos in Groups II and III showed more damage, characterised by cytoplasmic vacuolisation and cellular membrane disruption. Most of the damage appeared to be caused by the freeze‐thaw process, but some morphological changes seen in mitochondria may be caused by glycerol.
Transvaginal ultrasound‐guided follicular aspiration of equine oocytes
Authors: COOK N. L. , SQUIRES E. L. , RAY B. S. , JASKO D. J. 
Published: June 2010

SummaryFollicular aspiration was performed in 30 cyclic mares during each oestrus and every dioestrus in which >4 follicles 10–15 mm in size were present. During the final oestrous cycle, 15 mares were superovulated with crude equine pituitary extract before aspiration. With the oestrous mares (99 preovulatory follicles yielding 62 (63%) oocytes) 3 follicular aspiration techniques were examined: a 12‐gauge double‐lumen needle, allowing continuous rinsing of the follicle, provided the best oocyte recovery, 36/43 (84%) compared with the single‐lumen needle (24/47; 51%) or the wire‐loop technique (2/9; 22%) (P<0.05). During dioestrus, 71 oocytes were recovered from 323 follicles (22%): oocyte recovery was not affected (P>0.05) by aspiration technique performed (16‐gauge needle with simple or continuous rinsing). Follicles <15 mm in size gave higher (P<0.05) oocyte recovery rates 36/118; 31%) than did follicles >20 mm in size (3/38; 8%). In the superovulated mares 22 oocytes were recovered from 36 preovulatory follicles (61%). We suggest that transvaginal ultrasound‐guided follicular aspiration is a low‐risk, repeatable method for in‐vivo collection of equine oocytes.
The in‐vitro block to development and initiation of transcription in early equine embryos
Authors: BALL B. A. , IGNOTZ G. G. , BRINSKO S. P. , THOMAS P. G. A. , MILLER P. G. , ELLINGTON J. E. , CURRIE W. B. 
Published: June 2010

SummaryCoculture of early cleavage‐stage equine embryos with other cell types, primarily oviductal epithelial cells, can support development to blastocystsin vitro.Embryos cultured in complex medium without cellular support develop at a significantly poorer rate and appear to undergo a developmental blockin vitro.In 2 experiments, 1–8‐cell embryos (n= 15) were cultured in Ham's F12: Dulbecco's MEM for 5 days or until morphological degeneration occurred. Embryos were assessed for stage of development and quality score on a daily basis. At the end of culture, embryos were stained to determine the number of nuclei present or were fixed and sectioned for evaluation by light microscopy. Additional embryos (n= 8) collected on Days 2–7 after ovulation were labelled with [3H]uridine and incorporation was determined by autoradiography.Of 15 embryos cultured without cellular support, 3 reached the morula stage and the remaining 12 embryos cleaved to the 8–16‐cell stage before undergoing morphological degeneration. [3H]uridine was incorporated into embryos at the 8‐cell stage or later, but no incorporation was detected in embryos at the 4‐cell stage. These results indicate that early equine embryos appear to undergo a developmental blockin vitroat the 8–16‐cell stage, relief of which is temporally associated with the onset of embryonic transcription.
Gonadotrophin treatments increase ovulation rate but not embryo production from mares
Authors: PALMER E. , HAJMELI G. , DUCHAMP G. 
Published: June 2010

SummaryPony mares were treated with crude equine pituitary extract (CEG) or an FSH‐enriched fraction from the same extract during the anovulatory or ovulatory season. The animals were treated during 2 successive cycles at each season. About 3 follicles achieved the preovulatory stage and ovulated but only 0.6 embryos were obtained after each treatment. There was no influence of season, hormone or treatment cycle on ovulation and embryo rates.Despite the increased ovulation rate, there was no improvement in embryo production (3.0 follicles, 2.8 ovulations, 0.6 collected embryos in 60 treatment cycles, 1.0 follicle, 1.0 ovulation and 0.6 embryos in 28 untreated cycles). However, the treatment can increase the number of embryos in winter (3.3 ovulations and 0.6 embryos, 30 cycles) compared with no responses in the normally anoestrous mare at this time.
Embryo transfer in anoestrous recipient mares: attempts to reduce altrenogest administration period by treatment with pituitary extract
Authors: LAGNEAUX D. , PALMER E. 
Published: June 2010

SummaryGroups of ovariectomised and anoestrous mares were treated with altrenogest and used as recipients for embryo transfer. Progesterone concentrations in all ovariectomised, pregnant mares increased only after 85 days of pregnancy, but in 2 out of 4 anoestrous pregnant mares progesterone increased between Days 40 and 50 of pregnancy. Follicular growth and luteinised follicles suggested that altrenogest could be withdrawn earlier. To test whether exogenous LH treatment could stimulate earlier onset of ovarian progesterone secretion, anoestrous, recipient pregnant mares treated with altrenogest were treated with LH (25 mg CEG (crude equine gonadotrophin) im daily (N=5). Two of the 4 control mares ovulated at Days 58–60 and plasma progesterone increased. The other 2 mares did not ovulate. In the mares treated with CEG, altrenogest treatment was withdrawn in 3 on Days 45, 50 and 55 respectively. One mare aborted on Day 54 when endogenous progesterone was still very low and there was no indication of ovulation and/or luteinisation in the 5th mare. There was no significant difference in increasing progesterone concentrations between CEG‐treated mares and untreated mares, suggesting that such treatment in anoestrous recipient mares is relatively inefficient.
Special surgical transfers of horse embryos
Authors: MULLER Z. , CUNAT L. 
Published: June 2010

SummaryTwo surgical methods of equine embryo transfer were developed. In Exp. 1, a long needle was used to puncture the vaginal wall and wall of the uterine horn and deposit the embryo: 3 pregnancies from 8 embryo transfers were confirmed at 50 days and 1 embryo was lost between 15 and 30 days.In Exp. 2, an endoscope was introduced through the flank of the mare into the abdominal cavity. Under the optical control and fixation of the uterine horn by grasping, an embryo was inserted in the lumen of the uterine horn: 3 pregnancies from 7 transfers were confirmed at 50 days of pregnancy.Surgical and non‐surgical embryo transfers for comparison resulted in 7 pregnancies from 10 surgical transfers and 4 pregnancies and 1 embryo loss from 12 nonsurgical transfers.
Commercial embryo transfer in polo ponies in Argentina
Authors: RIERA F. L. , McDONOUGH J. 
Published: June 2010

SummaryDifferent techniques in an embryo transfer programme were studied under field conditions on polo pony mares in Argentina. Comparisons were made between embryo recovery rates from donor mares inseminated before or after ovulation, between two embryo recovery methods and between two embryo transfer methods. In addition, pregnancy rates were compared among recipients that received an embryo on 1, 2 or 3 occasions. Also, embryo recovery and pregnancy rates were compared in mares that underwent successive embryo recovery attempts.The findings suggest that the success of embryo transfer performed under field conditions is enhanced by inseminating mares before ovulation, recovering embryos with an in‐line filter method and transferring the embryo into the uterine horn instead of the uterine body. Differences in pregnancy rates for recipient mares that had received embryos on 1, 2 or 3 occasions were not significant. Embryo recovery rates and pregnancy rates after transfer were not significantly different in mares in which embryo recovery attempts were performed between 1 and 10 times.
Difficulties in definition of equine osteochondrosis; differentiation of developmental and acquired lesions
Authors: POOL R. R. 
Published: June 2010

SummaryThis paper reviews most of the important clinical syndromes currently considered as examples of articular osteochondroses based on the belief that they arise from a primary lesion in the articular cartilage that produces failure in endochondral ossification. Arguments are made why a number of syndromes are not osteochondroses. Because morphological lesions resembling osteochondrosis can be produced at osteochondral junctions from primary disorders centred in the growth cartilages (dyschondroplasia) or in the capillary bed that replaces the cartilage model during endochondral ossification, the definition of osteochondrosis in horses needs to be reexamined. Because the morphology of an individual lesion of osteochondrosis provides little insight into its fundamental cause, this paper suggests that the pattern of skeletal distribution of the lesions in affected individuals may help distinguish between foals with the idiopathic (constitutional defects in the cartilage model) and acquired forms of osteochondrosis. In foals with acquired osteochondrosis when the cause of the defect in endochondral ossification is known, the cause of the disorder should be included in naming the clinical syndrome, e.g. traumatic osteochondrosis or zinc‐induced osteochondrosis. The search for the key to the pathogenesis of osteochondrosis in horses can only begin after the fundamental mechanisms causing perturbations of endochondral ossification are better understood.
Osteochondrosis/dyschondroplasia: a failure of chondrocyte differentiation
Authors: THORP B. H. , FARQUHARSON C. , KWAN A. P. L. , LOVERIDGE N. 
Published: June 2010

SummaryOsteochondrosis/dyschondroplasia is a focal disorder of endochondral ossification which occurs in most species and is characterised by retention of epiphyseal or growth plate (physeal) cartilage. Epiphyseal and physeal cartilage in different species is very similar at the molecular and cellular levels. Therefore, the high frequency of lesions, ease of induction and a similar pathology to that found in other species makes avian tibial dyschondroplasia (TD) a useful model for the general study of osteochondrosis. In addition some of the methods successfully applied to the investigation of avian TD may indicate strategies for the investigation of equine OCD/dyschondroplasia.TD is characterised by an avascular mass of cartilage containing partly hypertrophied (transitional) chondrocytes. Changes occurring during the initiation of a lesion can be obscured by subsequent pathology and caution must be exercised in interpreting results of studies of established lesions. In‐situ biochemistry and immunocytochemistry of chondrocytes in TD indicates that the accumulation of cartilage is not caused by increased chondrocyte proliferation or decreased osteoclast/chondroclast activity. Anaerobic glycolysis is not increased in the transitional chondrocytes, showing that oxygen supply to these cells is not limiting. These initial studies confirmed that TD is the result of a failure of chondrocytes to differentiate fully and are supported by an investigation in which genetic selection for TD resulted in accumulations of transitional chondrocytes.Transitional chondrocytes contain high concentrations of TGF‐b and the product of the proto‐oncogene, c‐myc. In TD these cells are deficient in TGF‐β and c‐myc. Alkaline phosphatase and Type X collagen mRNA are increased but a lower concentration of collagen X within the matrix indicates a defect in its secretion or incorporation within the matrix. Type II collagen expression remains unchanged in dyschondroplasia. These data enable the point at which the arrest of chondrocyte differentiation occurs to be identified more precisely.These methodologies are starting to reveal the sequence of events which results in the initiation of dyschondroplasia in domestic poultry. Strategies developed, tested and applied in the investigation of TD can be applied to studies of osteochondrosis/dyschondroplasia in other species including equids.
A review of possible metabolic relationships of copper to equine bone disease
Authors: CYMBALUK NADIA F. , SMART MARION E. 
Published: June 2010

SummaryCopper (Cu) deficiency is a putative cause of equine bone disease. A review of the literature describing Cu metabolism and presumptive Cu deficiency in the horse is presented. The clinical and pathological consequences of primary and secondary Cu deficiency in equids are discussed with special reference to skeletal abnormality. Diagnostic criteria and recommendations for supplementation are provided.