[The C cell system and experimental thyroid apudomas in the rat: the combined action of 2-acetylaminofluorene and chlorpromazine in inducing systemic medullary type tumors. An ultrastructural study].

: Previous chronic administration of chlorpromazine (CPZ) before the start of the 2-acetylaminofluorene (2-AAF) action and during the cancerogenic process systematically facilitate the growth of apudome-like medullary tumors inside the thyroid gland. Ultrastructural studies of normal C cells, adenomatous C cells and cancerous C cells derivated from the normal cellular type show various specific transformations of few intracytoplasmic organelles. In the Golgi apparatus, the path of main maturation of calcitonin-like granules seems the same in the normal and in the adenomatous cells. On the contrary, the amount of calcitonin-like granules falls in the tumoral extensive tissue even though the golgian activity turns towards a high abnormal proliferation of clathrin vesicles or coated vesicles. This new fact is directly related with numerous extensions and repairs of much damage of the neoplastic cell membranes. Finally, the large medullary tumors (showing many atypic mitosis in glandular neoplastic C cell-type) are deeply penetrated by extensive and irregular vegetative nervous fibers.