Proceedings of the 5th International Symposium on EQUINE ...

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Havemeyer Foundation Monograph Series No. 3THE EQUIDS AND EMBRYOS OF J. COSSAR EWART:A GLIMPSE OF VICTORIAN AND EDWARDIANRESEARCH IN REPRODUCTIONK. J. BetteridgeDepartment <strong>of</strong> Biomedical Sciences, Ontario Veterinary College, University <strong>of</strong> Guelph, Guelph,Ontario N1G 2W1, CanadaJames Cossar Ewart (1851–1933) lived throughtimes <strong>of</strong> turmoil in <strong>the</strong> biological sciences,particularly those related to <strong>the</strong> understanding <strong>of</strong>heredity. In particular, <strong>the</strong>re was conflict between‘men <strong>of</strong> science’ and practical animal breeders, aswell as among scientists, as to whe<strong>the</strong>r ‘telegony’ -<strong>the</strong> concept <strong>of</strong> one sire affecting <strong>the</strong> phenotype <strong>of</strong> adam’s subsequent <strong>of</strong>fspring by different sires - is areal phenomenon. Those disputes, which preceded<strong>the</strong> rediscovery <strong>of</strong> Mendel’s observations, spawned2 different experimental approaches to <strong>the</strong> study <strong>of</strong>heredity, both <strong>of</strong> which were significant to <strong>the</strong>development <strong>of</strong> equine embryo transfer. First, <strong>the</strong>rewas <strong>the</strong> development, in rabbits, <strong>of</strong> <strong>the</strong> transferprocedure itself, by Walter Heape and GeorgeRomanes, independently. Ewart, on <strong>the</strong> o<strong>the</strong>r hand,undertook a large-scale crossbreeding experimentwith horses and zebras at Penycuik, nearEdinburgh. He tested <strong>the</strong> evidence for telegony thathad been based on <strong>the</strong> famous case <strong>of</strong> LordMorton’s mare. She had supposedly been‘infected’ by a quagga sire and produced a stripedfoal when subsequently bred to an Arab stallion.Ewart’s studies also led to <strong>the</strong> first descriptions <strong>of</strong><strong>the</strong> chorionic girdle (commemorated in a previousHavemeyer <strong>Symposium</strong>), <strong>of</strong> equine embryos andfoetuses from <strong>the</strong> third week <strong>of</strong> gestation, and <strong>the</strong>irrelevance to <strong>the</strong> phylogenetic history <strong>of</strong> <strong>the</strong> horse,and <strong>of</strong> <strong>the</strong> value <strong>of</strong> comparative observations inreproduction. In considering Ewart’s contributionsto our science, published information will besupplemented with material gleaned from hispapers and correspondence held at <strong>the</strong> University<strong>of</strong> Edinburgh. On <strong>the</strong> positive side, <strong>the</strong> lattermaterial documents interesting exchanges betweenEwart and several giants in our field (Heape,Marshall, Hill, Hammond and Catchpole). Letterstell familiar tales <strong>of</strong> <strong>the</strong> difficulties <strong>of</strong> financingresearch, and less familiar ones <strong>of</strong> contact withroyalty, Downing Street and <strong>the</strong> aristocracy.Against this must be balanced disturbing tracts oneugenics. Overall, however, <strong>the</strong> material <strong>of</strong>fersinstructive insight into <strong>the</strong> life and times <strong>of</strong>:“He who had talked with Darwin and Huxley,who had witnessed <strong>the</strong> change in human thoughtconsequent upon <strong>the</strong> promulgation <strong>of</strong> evolution<strong>the</strong>ory, [and] was notable amongst his fellows for<strong>the</strong> reason that he, a pr<strong>of</strong>essional biologist and aUniversity pr<strong>of</strong>essor, left <strong>the</strong> laboratory for <strong>the</strong>farm to use animals <strong>of</strong> economic importance as hisexperimental material and to attack problemswhich not only possessed a scientific interest, butwhich, in <strong>the</strong>ir solution, might confer advantage on<strong>the</strong> community.”(From <strong>the</strong> obituary <strong>of</strong> J. Cossar Ewart byF.A.E. Crew, Animal Breeding Abstracts, 1934).3
Equine Embryo TransferHYSTEROSCOPIC UTEROTUBAL INSEMINATION OFMARES WITH LOW NUMBERS OF FROZEN-THAWEDEJACULATED AND EPIDIDYMAL SPERMATOZOAL. H. A. Morris, C. Tiplady, S. Wilsher and W. R. AllenEquine Fertility Unit, Mertoun Paddocks, Woodditton Road, Newmarket, Suffolk CB8 9BH, UKINTRODUCTIONFirst cycle conception rates for mares inseminatedwith frozen-thawed ejaculated spermatozoa havebeen reported to range from 32% (Vidament et al.1997) to 58% (Samper 1995). These figures havebeen achieved after performing repeated ultrasoundexaminations <strong>of</strong> follicular development at 4–8 hintervals to ensure that a minimum <strong>of</strong> 200–500million spermatozoa are deposited in <strong>the</strong> uterusclose to <strong>the</strong> time <strong>of</strong> ovulation. The present studysought to inseminate mares hysteroscopically(Morris et al. 2000) with low numbers <strong>of</strong> frozenthawedejaculated and epididymal spermatozoa at afixed time after administration <strong>of</strong> an ovulationinducingdose <strong>of</strong> human Chorionic Gonadotropin(Chorulon, Intervet, Milton Keynes, UK).MATERIALS AND METHODSSemen was collected by artificial vagina from twoidentical twin Pony stallions <strong>of</strong> known highfertility, and by flushing <strong>the</strong> epididymes <strong>of</strong> testiclesrecovered during routine castration <strong>of</strong> youngThoroughbred colts. Both <strong>the</strong> ejaculated andepididymal samples were extended in an equalvolume <strong>of</strong> a skim milk – glucose diluent beforebeing centrifuged at 300 g for 10 min. Thesupernatant was decanted and <strong>the</strong> sperm pellet wasresuspended in ei<strong>the</strong>r a Tris-based or a HEPESbufferedextender supplemented with glycerol. Theresulting sperm suspensions were <strong>the</strong>n frozen inliquid N 2 vapour in 0.5 ml straws. At thawing <strong>the</strong>straws were placed in a 37ºC water bath for 30 s.The ovaries <strong>of</strong> <strong>the</strong> oestrous mares to beinseminated were monitored ultrasonographicallyonce daily and, when a dominant follicle <strong>of</strong> ≥35mm diameter was observed an ovulation-inducingdose <strong>of</strong> 1,500–3,000 iu hCG was administered iv.Between 30 and 32 h later, <strong>the</strong> mares wereinseminated as follows: Group 1: 25 millionspermatozoa in 0.5 ml diluent by conventionalartificial insemination (n = 12); Group 2: 25million spermatozoa in 0.5 ml diluent, depositedhysteroscopically on <strong>the</strong> uterotubal papilla at <strong>the</strong>tip <strong>of</strong> <strong>the</strong> uterine horn ipsilateral to <strong>the</strong> impendingovulation (n =14); Group 3: 5 million spermatozoain 0.1 ml diluent, deposited hysterscopically on <strong>the</strong>ipsilateral uterotubal papilla (n = 34); Group 4: 5million spermatozoa in 0.1 ml diluent depositedhysteroscopically in <strong>the</strong> posterior body <strong>of</strong> <strong>the</strong>uterus to simulate <strong>the</strong> site <strong>of</strong> conventional artificialinsemination (n = 8); Group 5: 5 millionspermatozoa in 0.1 ml diluent depositedhysteroscopically on <strong>the</strong> uterotubal papillacontralateral to <strong>the</strong> impending ovulation (n = 12);Group 6: 300 million epididymal spermatozoa in0.5 ml diluent deposited hysterscopically on <strong>the</strong>uterotubal papilla ipsilateral to <strong>the</strong> impendingovulation (n = 25); Group 7: 5 million epididymalspermatozoa in 0.1 ml diluent depositedhysteroscopically on <strong>the</strong> uterotubal papillaipsilateral to <strong>the</strong> impending ovulation (n = 19).RESULTSOf all <strong>the</strong> 148 inseminated mares, 124 (83.8%) hadovulated within 15 h after <strong>the</strong> insemination inresponse to <strong>the</strong> gonadotropin injection and <strong>the</strong>seanimals were <strong>the</strong>refore included in <strong>the</strong> results,which are summarised in Figure 1.DISCUSSIONThe results demonstrate clearly that highconception rates are achievable in mares4
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