DEVELOPMENTAL POTENTIAL OF BOVINE EMBRYOS RECONSTRUCTED FROM ENUCLEATED MATURED OOCYTES FUSED WITH CULTURED SOMATIC-CELLS

Muscle and skin biopsies taken from bovine fetuses and young calves ha ve been used as a source of donor nuclei for cloning experiments. Afte r culture, cells were individually fused to enucleated matured oocytes and the resulting blastocysts obtained after 7 d of culture (3-8 % de pending on the cell type) were transferred to foster recipient heifers . Two calves, a female and a male, both originating from muscle cells were born, and four additional pregnancies have surpassed mid-term ges tation. The pregnancies include one fetus established from a transgeni c nucleus from a fetal skin cell, and another one resulting from a ski n biopsy performed on a female calf. Our data demonstrate that nuclei from cultured bovine somatic cells obtained from differentiated tissue s can be made multipotent. (C) Academie des sciences/Elsevier, Paris.