The testing of cell invasiveness in embryonic tissue and in cell culture.

The subcutis of 11-day-old chick embryos, 15- to 18-day-old mouse embryos and the skin muscle tissue of human fetus were stretched on lens paper in a Petri dish and seeded with a piece of LED-Widr or HDC cell sheet. Mem + 10% FCS was added. After three days incubation the material was fixed, sectioned and H-E stained. In the second part of our investigation several cell lines were prepared on cover slips. When confluent, the cultures were inoculated with 1-2 drops of cell suspension of another cell line. Three days after the seeding of cell suspension on the confluent cell sheet the cultures were fixed and stained. It can be seen in the organ cultures that LED-Widr cells closely adhere to the embryonic tissue which in some places they are invading. In tissue culture examination we found that heteroploid cells seeded on a confluent sheet of diploid cells adhered but that a diploid cell seeded on epithelial-like heteroploid cells would not adhere. The testing of invasiveness in embryonic tissue in organ culture showed that it can be a useful model. By seeding suspended cells of fibroblast lines on a confluent sheet of heteroploid cell lines their contact inhibition or their invasive ability can be determined. The seeding of heteroploid cell lines on diploid cell lines can be used as a model for the study of the mechanism of invasion into normal tissue and for the in vitro study of invasion inhibiting properties of certain substances.