[Light and electron microscopic study of the degree of differentiation of cancer of the large intestine].

Two groups of human rectal tumors histologically identified as well- and poorly-differentiated carcinomas were studied by means of electron microscopy. Some tumors of the former group consisted of undifferentiated cells only, while the others comprised chiefly differentiated cells (goblet cells, enterocytes, oncocytes and/or endocrine cells). Some tumors of the latter group consisted of undifferentiated cells only or partially. The remaining tumors were formed mostly of differentiated cells with organ-specific characteristics. It is inferred that a comparison of the results of identification of the degree of tumor cell differentiation by light and electron microscopy may be inconclusive. This conclusion may provide a plausible explanation of the difference in prognosis and response to treatment of rectal tumors of similar histological patterns.