DISTRIBUTION OF HETEROLOGOUS TUMOUR CELLS IN CHICK EMBRYOS FOLLOWING INTRAVENOUS INJECTION

The quantitative distribution of 3H-labelled cells from 5 different mouse tumours following intravenous injection into chick embryos has been investigated. The lodgement of tumour cells in the organs was very rapid. Death of non-growing tumours was reflected in the extensive reutilization of radioisotope by chick embryo cells. The relatively poor growth of strain specific tumours was not due to any characteristic differences in their organ distribution or the speed with which they were trapped. For any single tumour the extent of subsequent growth within different organs corresponded well with the tumour trapping efficiency of the organs, with two exceptions. The brain trapped few tumour cells but supported vigorous tumour growth, possibly because it is an immunologically protected site. The spleen trapped many cells but was a poor site for tumour growth, possibly because of its high R.E.S. activity. There were indications that with equal density of seeding oftumour cells the lung provided a much better site for tumour growth than the liver. With different tumours there were large differences in the tumour trapping efficiencies of several organs, and these differences corresponded well with the extent of subsequent tumour growth. These differences in distribution could not be solely accounted for by differences in cell size. Both mechanical and organ- and tumour-specific factors appear to be involved in the site of formation of metastases in this system. © 1969.