[Ultrastructural study of explants of carcinoma of the large intestine during prolonged organ cultivation].

The electron microscopical study on organ cultures of colonic carcinoma has shown that tumour cells form typical for this kind of tumours glandular-like structures which consist of ultrastructural differentiated cells with organospecific features of brush-border and goblet cell types. Depending on the terms of cultivation the consecutive stages of ultrastructural differentiation have been retraced starting from undifferentiated cells (the 5th day of the experiment) up to structurally matured differentiated cells (the 7th-9th days of experiment). The tumour growth in the organ cultures is realized mainly by an explant itself building up processes from its peripheral cell lining and its invagination inside a piece. Glandular-like structures which are forming on the ends of processes and invaginations have undergone further separation. The question of monoclonal origin of colonic carcinoma in organ cultures is discussed.