[Enzyme histochemical and electron microscopic studies on the problem of infiltrating (invasive) tumor growth. 2....

Tumour cells of 12 mammary carcinomas, 14 ovarian carcinomas, 10 malignant melanomas of the man and 24 transplantation tumours of rats were studied by the electron microscope in their relation to the surrounding tissue. On the contact surface between tumour cells (mammary carcinomas) and surrounding tissue a focal or extensive loss of the cell membranes in seen. This causes a release of cytoplasmic parts, especially of ribosome-like material. The adjacent connective tissue shows a splitting of the collagenous bundles and a fibrilloysis. In the infiltrated skeletal muscle (ransplantation tumours of rats) the tumour cells connect directly to the muscle cells. These are eroded showing ruptured fibres and loosened filaments and mitochondria, giving a moth eaten appearance. As a result of these findings we presume that the destruction of the tissue surrounding the tumour is mainly initiated by the tumour cells. For ovarian carcinomas and malignant melanomas (with few exceptions) there is no morphological sign for a specific enzymatic-lytic effect of the living tumour cells to the surrounding tissue. The findings are discussed in the aspect of the invasive tumour growth.