Printed in Great Britain © Company of Biologists Limited J979 SURVIVAL OF CELLS IMPLANTED IN THE EMBRYONIC CHICK LIMB BUD: A DIFFERENCE BETWEEN NORMAL AND

Cells from normal rat brain tissue did not survive and few cells could be found 1 d after grafting. In contrast, cells from a glioma and a carcinogen-treated rat brain survived well and many mitoses were observed. These malignant cells also invaded the limb. The behaviour of normal and malignant cells was followed at shorter times after grafting and some invasion by the normal cells was detected. The first signs of degeneration of normal cells were apparent around 7 h after grafting, and after this the grafts progressively deteriorated. These results support the idea that the ability of cells to survive and grow in embryonic tissues is a charac-teristic of malignant cells. The findings are discussed in relation to mechanisms of tumour formation