A study of some tumours of human origin—II: Chromosome and late replication analysis of parental tumours, metastasis and ascites of the HR 18 rat tumour

Abstract

The HR 18 rat tumour derived from a human melanocarcinoma was propagated in solid and permanent ascites form, and heterotransplanted in AKR mice. In the new host the HR 18 tumour preserved its original chromosome constitution and behaved as aggressively as in rat. The karyological uniformity of the HR 18 tumour may account for the invading character of the tumour, as a selected cellular variant, with high malignant potentiality. The comparative chromosome analysis of parental tumour, lung metastasis and ascites form revealed similarities between the solid tumoural forms and differences between these latter and the ascites form. The tumoural growth medium influences the chromosome structure of the neoplastic cells. Late replication pattern of ascites cells was characteristic to rat, some heterochromatic regions were altered, which may be correlated to the malignant transformation of the cells.