The Fine Structure of Nuclei in Certain Human Malignant Neoplasms

Abstract

The nuclei of malignant human neoplasms from the cervix, stomach, bronchus, colon, kidney, small intestine (carcinoid), thyroid; acute leukemia; and a malignant melanoma were studied with electron microscopy and contrasted with normal cells from comparable sites. These observations were correlated with those made through the use of Feulgen stains and azure B before and after ribonuclease digestion. Normal nuclei exhibited, with electron microscopy, a uniformly dispersed, fine granular structure. Denser nuclear granules were present, in addition to finer and less dense granules, the latter more numerous. In the malignant neoplasms studied, the nuclear fine granules were arranged in aggregates and were more concentrated just inside the nuclear membrane and around the nucleoli. The denser nuclear granules occurred in larger clumps and tended to be arranged around the edges of the aggregates of the less dense granules. Evidence obtained from correlation with Feulgen and azure B stains suggested that the finer nuclear granules of electron microscopy are deoxyribo-nucleoprotein (DNP), and that possibly the denser granules are ribo-nucleoprotein (RNP). Nucleoli of malignant cells were larger and more irregular in outline. They contained denser and lighter granules, the former predominating. Nucleoli had the appearance of being "uncoiled" in malignant cells, Feulgen stains and azure B after ribonuclease digestion suggested the presence of a significant amount of DNP in the nucleoli of malignant neoplastic cells. The possible relation between these observations and ribonucleoprotein synthesis in malignant neoplastic cells was discussed.