DEVELOPMENT OF IMMORTALIZED ENDOMETRIAL EPITHELIAL AND STROMAL CELL-LINES FROM THE MINK (MUSTELA-VISON) UTERUS AND THEIR EFFECTS ON THE SURVIVAL IN-VITRO OF MINK BLASTOCYSTS IN OBLIGATE DIAPAUSE

Mink endometrial cell lines were established by stable transfection of a plasmid vector encoding the SV40 large T antigen driven by the huma n beta-actin promoter. A second plasmid vector, pSV2neo, was employed for selection of transfected cells. Specificity and homogeneity of con sequent cell lines were evaluated by immunocytochemistry employing ant ibodies against cytokeratin, desmin, and vimentin. Cytokeratin was fou nd exclusively in epithelial cells, whereas vimentin appeared primaril y in stromal cells. Neither cell line showed detectable desmin activit y. These cell lines along with Buffalo rat liver (BRL) cells were empl oyed in coculture with mink embryos in obligate diapause. Mink stromal and BRL cell lines were most effective in enhancing embryo survival i n vitro. The percentages of cocultured embryos that survived for 72 h or more were 65% with epithelial cells, 75% with stromal cells, 68% wi th the combination of stromal and epithelial cells, and 93% with BRL c ells, Only 23% of the embryos cultured without cells survived beyond 4 8 h. Embryo growth was also observed; some embryos in coculture showed trophoblastic outgrowth and adhesion to the cell surfaces. These resu lts demonstrate that mink embryos in obligate delay can survive and de velop in culture and that coculture with uterine or BRL cells increase s the length and frequency of survival.