Data/hora: 23/06/2024 17:51:14

Biblioteca(s): 	Embrapa Caprinos e Ovinos.	
Data corrente: 	23/03/2005	
Data da última atualização: 	17/11/2009	
Autoria: 	DE SOUSA, P. A.; WALKER, S.; KINK, T. J.; YOUNG, L. E.; HARKNESS, L.; RITCHIE, W. A.; TRAVERS, A.; FERRIER, P.; WILMUT, I.	
Título: 	Evaluation of gestational deficiencies in cloned sheep.	
Ano de publicação: 	2000	
Fonte/Imprenta: 	Theriogenology, v. 53, n. 1, p. 241, 2000.	
Idioma: 	Inglês	
Notas: 	Edição de proceedings Annual Conference of the International Embryo Transfer Society, Maastricht, The Netherlands, jan. 2000.	
Conteúdo: 	DevelopmentaI failure associated with cloning by nuclear transfer (NT) is poorly understood. To address this we compared the morphology of Day 35 NT sheep fetuses versus control fetuses from in vivo- or in vitro-produced (IVP) embryos. In the first experiment, fetuses were cloned from a Black Welsh FetaI fibroblast cellline (BL Wl) or created by artificial insemination (AI) of Black Welsh or Blackface ewes with Black Welsh semen. Subsequently, NT fetuses cloned from a different fibroblast line (BLW6) were compared with Blackface x SuffoIk F1 fetuses derived from IVP embryos cultured by the SOF system (WaIker et aI., Biol Reprod 1996;55:703-708). Embryos were cloned ftom serum-starved cells as previously described (Wilmut et aI., Nature 1997;385:810-813). Oocytes for NT were collected using phosphate-buffered saline (PBS) and manipulated in SOF. NT fusion and activation was by 3 x 80 ~sec pulses of 1.25 kV/cm2 in 0.3 M mannitol, 0.1 mM MgCl2, 0.05 mM CaC l2 NT embryos developed to the blastocyst stage in temporary recipient ewes before final transfers. Reconstruction of 288 and 160 oocytes with BLWl and BLW6, respectively, yielded comparable rates of fusion (60.8 vs 66.3%), aIthough the percentage of fused oocytes forming blastocysts was 2.5 times higher for BLW6 (20.7%) than for BLWl (8.6%). Of 9 AI fetuses examined, alI had normal fetaI and placentaI morphologies expected for Day 35. Transfer of 71 IVP embryos into 30 ewes, resulted in 22 (73%) pregnant on Day 35. From 10 ewes (receiving 21 embryos), 17 fetuses (81%) were recovered. Fifteen (88%) were normal, 1 showed slight chorionic hypoplasia, and one was mummified. In contrast, transfer of 21 (BLWl) and 22 (BL W6) NT embryos into 12 and 11 ewes respectively, yielded 7 (33%) and 8 (36%) fetuses respectively. Only 3 (42%) BLWl and 2 (25%) BLW6 NT fetuses were nonnaI, with the rest being developmentally retarded. Severe chorionic hypoglasia was evident in 6 BLWl (86%) and 6 BLW6 (75%) fetuses, respectively. Our results reveaI a high incidence of developmentaI retardation in cloned fetuses. This is either correlated or causally linked with deficiencies in placentation.	
Palavras-Chave: 	Placentação.	
Thesagro: 	Clonagem; Deficiência; Embrião; Ovino; Prenhez; Reprodução Animal.	
Categoria do assunto: 	--	
Registro original: 	Embrapa Caprinos e Ovinos (CNPC)	
Exemplares: 	CNPC - (17567-1) - ADC - AP - -- -  -  - v.53,p.241 - DIS