Havemeyer Foundati<strong>on</strong> M<strong>on</strong>ograph Series No. 3TABLE 1: Developmental capacity <str<strong>on</strong>g>of</str<strong>on</strong>g> horse oocytes following ICSI and according to follicle sizeand cumulus morphologyType <str<strong>on</strong>g>of</str<strong>on</strong>g> cumulus- No. ICSI No. survived No. cleaved N. <str<strong>on</strong>g>of</str<strong>on</strong>g> morula/blastocystoocyte complexes (% <str<strong>on</strong>g>of</str<strong>on</strong>g> injected) (% <str<strong>on</strong>g>of</str<strong>on</strong>g> survived) <strong>on</strong> Day 7 (% <str<strong>on</strong>g>of</str<strong>on</strong>g> cleaved)Compacted 11 9 7 2(large follicles) (82 a ) (78 a ) (29 a )Compacted 45 43 36 11(small follicles) (96 a ) (84 a ) (31 a )Expanded 34 32 19 2(small follicles) (94 a ) (59 a ) (11 b )Total 90 84 62 15(93) (74) (24)Numbers within columns with different letters are significantly different (P
Equine Embryo Transferbefore maturati<strong>on</strong> but it is difficult to visualise<str<strong>on</strong>g>the</str<strong>on</strong>g>m because <str<strong>on</strong>g>of</str<strong>on</strong>g> <str<strong>on</strong>g>the</str<strong>on</strong>g> presence <str<strong>on</strong>g>of</str<strong>on</strong>g> <str<strong>on</strong>g>the</str<strong>on</strong>g> cumulus andsome more are damaged during <str<strong>on</strong>g>the</str<strong>on</strong>g> removal <str<strong>on</strong>g>of</str<strong>on</strong>g> <str<strong>on</strong>g>the</str<strong>on</strong>g>cumulus that it is particularly difficult in thisspecies. Seventy nine per cent <str<strong>on</strong>g>of</str<strong>on</strong>g> <str<strong>on</strong>g>the</str<strong>on</strong>g> survivingoocytes had <str<strong>on</strong>g>the</str<strong>on</strong>g> first polar body. Our data indicatethat oocytes with a compacted cumulus have ahigher developmental competence as compared tooocytes surrounded by an expanded cumulus.Although <str<strong>on</strong>g>the</str<strong>on</strong>g> numbers <str<strong>on</strong>g>of</str<strong>on</strong>g> viable oocytes per ovaryis small, <str<strong>on</strong>g>the</str<strong>on</strong>g> percentage <str<strong>on</strong>g>of</str<strong>on</strong>g> <str<strong>on</strong>g>the</str<strong>on</strong>g>m developing intotransferable embryos is comparable to what canbe obtained in a bovine in vitro producti<strong>on</strong>system.REFERENCESCochran, R., Meinjtes, M., Reggio, B., Hylan, D., Carter,J. Pinto, C., Paccam<strong>on</strong>ti, D. and Godke, R.A. (1998)Live foals produced from sperm-injected oocytesderived from pregnant mares. J. equine vet. Sci. 18,736-740.McKinn<strong>on</strong>, A.O., Lacham-Kaplan, O. and Trouns<strong>on</strong>,A.O. (1998) Pregnancies produced from fertile andinfertile stalli<strong>on</strong>s by intracytoplasmic sperminjecti<strong>on</strong> (ICSI) <str<strong>on</strong>g>of</str<strong>on</strong>g> single frozen/thawedspermatozoa into in vitro matured mare oocytes. 7th<str<strong>on</strong>g>Internati<strong>on</strong>al</str<strong>on</strong>g> <str<strong>on</strong>g>Symposium</str<strong>on</strong>g> in Equine Reproducti<strong>on</strong>,University <str<strong>on</strong>g>of</str<strong>on</strong>g> Pretoria, pp 137.Palmer, E., Bezard, J. Magistrini, M. and Duchamp, G.(1991) In vitro fertilisati<strong>on</strong> in <str<strong>on</strong>g>the</str<strong>on</strong>g> horse. Aretrospective study, J. reprod. Fert. Suppl. 44,375–384.Squires, E.L., Wils<strong>on</strong>, J.M., Kato, H. and Blaszczyk, A.(1996) A pregnancy after intracytoplasmic sperminjecti<strong>on</strong> into equine oocytes matured in vitro.Theriogenol. 45, 306.Zhang, J.J., Boyle, M.S., Allen, W.R. and Galli, C.(1989) Recent studies <strong>on</strong> in vivo fertilisati<strong>on</strong> <str<strong>on</strong>g>of</str<strong>on</strong>g> invitro matured horse oocytes. Equine. vet. J. Suppl. 8,101-104.34
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