TRANSPLANTATION OF A CELL-LINE DERIVED FROM A CANINE BENIGN MIXED MAMMARY-TUMOR INTO NUDE-MICE

The MCM-B2 canine mammary cell line was serially transplanted into nud e mice. The tumour masses consisted of elongated pleomorphic cells of varying size in the first to third passages; oval cells, becoming roun der, in the sixth to eighth passages; and cord-like, glandular and duc t-like structures with compact radiating projections in the ninth and tenth passages. Ultrastructural and immunohistochemical examination of round cells confirmed their epithelial cell nature, but the morpholog y of the elongated and oval cells was identical with that of the origi nal cell line. The findings suggest that the MCM-B2 cell line is a mul tipotential stem cell or is derived from glandular differentiation of mammary gland. (C) 1995 Academic Press Limited