[The importance of nucleolar morphology for the diagnostic cytology of malignomas of the thyroid (author's transl)].

The evaluation of the nuclear morphology for the diagnostic cytology of the various types of goiters with special regard to thyroid malignancy was studied. The material for the light microscopy was obtained from the goiters by means of aspiration biopsy with thin needle and that for electrone microscopy from the excision at the operation. Both the patterns of the nucleoli were compared. The nucleolus of the thyroid cell, like in other cells, is a marker of the RNA synthetic activity. Secondary it signals the intensity of the proteosynthetic activity, that means of secretory or proliferative processes. In thyroid cells, the increased activity has a different nucleolar pattern. For that reason the study of the nucleoli is very useful in differential diagnosis of thyroid malignancy. The cytochemical examination of the nucleoli by means of toluidine blue staining is in accord with the electron microscopic pattern, where the mutual relation of the fibrillar and granular components of RNA can be evaluated.