Abstract
Ultrastructural comparisons were made by transmission and scanning electron microscopy between Dunn and Potter's mastocytoma cells and normal mast cells of CDf/1 mice which were carriers of Dunn and Potter's mastocytoma cells or Wistar rat normal mast cells.
The mastocytoma cell was found to be round to oval with many irregular short microvilli. The nucleus of the mastocytoma cell had a few prominent nucleoli. It consisted mainly of euchromatin. Medium sized mitochondria were observed in moderate quantities in the cytoplasm. The mastocytoma cell had abundant ribosomes and several areas of tubular endoplasmic reticulum. It had a relatively well developed Golgi apparatus. The centrioles and small specific granules of the mastocytoma cells were localized in the neighborhood of the Golgi apparatus. Normal mast cells showed various cell profiles. The nucleus of the normal mast cell had no nucleolus. The chromatin consisted of almost equal amounts of euchromatin and heterochromatin. Several elongated mitochondria were found in the normal mast cell. There were a few areas of slightly dilated rough surfaced endoplasmic reticulum and a small number of ribosomes. The normal mast cell had a small Golgi apparatus and its cytoplasm was extensively occupied by large granules.
Scanning electron microscopy also revealed certain differences between these two types of cells. The mastocytoma cell was found to be generally much more villated than the normal mast cell. The surface architecture of the mastocytoma cell resembled that of other neoplastic cells. The use of the scanning electron microscope alone was insufficient to differentiate between the mastocytoma cell and mast cell.
The nucleus to cytoplasmic ratio of the mastocytoma cell was larger than that of the mast cell. The granule to cytoplasmic ratio of the mast cell was apparently larger than that of the mastocytoma cell. Quantitative analysis of these cells at the cell organella level was able to clarify the difference between the tumor cells and normal cells to some extent.
