[Ultrastructural variants of the cellular composition of human pulmonary adenocarcinomas]

Fifty-four lung adenocarcinomas of various degrees of differentiation were studied electron microscopically. Two groups of cells-differentiated, with the ultrastructural organ- and tissue-specific features, and undifferentiated, without such ultrastructural features were distinguished as a result of this study. Differentiated tumour cells may have ultrastructural features of pneumocytes II (osmiophilic membranous bodies), goblet cells and serous cells (mucous or serous granules), cylindrical cells (microvilli, cilia), squamous epithelium (tonofibrils, desmosomes) and possibly endocrine type cells (endocrine secretory granules) and pneumocytes I (pinocytotic vesicles). The quantitative correlation between differentiated and undifferentiated cells significantly varies with adenocarcinomas, in some tumours only undifferentiated cells being present. One or several cell types may be found in one tumour. There is a correlation between the degree of tumour differentiation at the histologic and ultrastructural level.