Electron microscopic, histologic, and histochemical features of the Walker carcinoma.

The morphology, including ultrastructure and histochemical features (particularly those related to enzymatic activity), of subcutaneous and artificially induced hepatic metastases of the Walker tumor has been investigated. The results of examinations by light and electron microscopy indicate that the designation of this tumor as a carcinoma appears more accurate than as a sarcoma or carcinosarcoma. Both local and hepatic growths qualitatively disclose a similar enzymatic pattern histochemically. Noteworthy is the failure to demonstrate succinic dehydrogenase and little cytochrome oxidase activity, although DPNand TPN-linked diaphorases are well demonstrated within the tumor cells. The relationship is not uncommon to a variety of malignant neoplasms and indicates the altered metabolism of such cells. Diaphorase as well as acid phosphatase, nonspecific esterase, lipase, and fl-glucuronidase activities which were also noted were less intense within tumor cells of hepatic metastases than in the subcutaneous growths. The electron microscopic appearance of subcutaneous growths and hepatic metastases of the Walker carcinoma were similar, resembling the appearance of a variety of other malignant tumors. Attention is called to the presence of pseudopodal cytoplasmic extensions between tumor and hepatic cells in the hepatic lesions. On the other hand, cell contact among tumor cells appeared as a more simple effacement of such cells. Similar enzymatic and ultrastructural features were noted in rapidly growing hepatic metastases induced by partial hepatectomy.