Cytological Characteristics of Fibroblasts and Sarcoma Cells Demonstrable by Phase‐contrast Microscopy

SYNOPSIS. Fibroblasts from subcutaneous connective‐tissue and from the stroma of tumours, and also sarcoma cells of a rapidly growing transplantable tumour have been studied by phase‐contrast microscopy. This technique demonstrates very clearly the increased mitochondrial content of the cytoplasm of the malignant cells and the more hyperchromatinic character of their nuclei. The cells comprising a small fragment taken from the periphery of a rapidly growing tumour exhibit a wide range of structure which deviates considerably from the cellular organization which is regarded as the morphological expression of most active malignant growth. Both the large nucleolar content of the nuclei (oxyribose nucleotides) as well as the considerable amount of chromatin (desoxyribose nucleotides) appear to be used up in the formation of the chromosomes at the prophase. Either the oxyribose nucleotides must be converted to the desoxyribose type during chromosome formation, or else the chromosomes must contain a considerable proportion of oxyribose nucleotides. During the reconstruction phase of mitosis the cytoplasm grows and the mitochondria increase in numbers before the nuclei have returned to the “resting” condition and reconstituted their nucleoli. The sarcoma cells readily undergo cytoplasmic budding (potocytosis). The intensity of this process seems to be correlated with the fluidity of the cytoplasm.