| Abstract: | Tumor cell nucleoli obtained from pleural effusions of 26 patients with different morphologic types of lung cancer were evaluated by silver staining. Distinct heterogeneity of tumor cell populations, with regard to the number of nucleoli as well as their functional activity in respect to ribosomal RNA synthesis, were shown to be the most common feature of all the tumors studied, regardless of their morphologic variants. One likely cause of heterogeneity in Ag nucleolar organized region (NOR) pattern of tumor cells may be due to chromosomal losses and gains from the karyotypes of acrocentric chromosomes with active NORs. Another possible cause for heterogeneity in nucleolar activity might be due to different reactions of tumor cells towards some humoral and cellular factors of pleural fluid including T-lymphocytes. |
