UMR Biologie du Développement et Reproduction, Institut National de la Recherche Agronomique, 78352 Jouy-en-Josas Cedex, France
(Received 3 February 2003; accepted 15 June 2003)
Production of cloned embryos by nuclear transfer from adult somatic cells is a novel and promising technique in animal biotechnology. In spite of numerous reported viable offspring in various species, the efficiency of the technique remains very low. Embryonic and fetal mortality occurs all along pregnancy and during the peri-natal life, even months after birth. Both embryonic and placental dysfunctions might be involved. However the precise causes of such developmental failures are still unknown. In the present review, we report data from different studies which described the main defaults which have been observed after embryonic cloning in various species. The putative molecular and cellular causes of these developmental failures are discussed.
Key words: cloning / development failure / nuclear reprogramming
Correspondence and reprints: Michel Guillomot guill@jouy.inra.fr