Ultrastructural studies on cells of hamster lung cultures after chronic exposure to whole smoke or the gas vapour phase of cigarettes.

High levels of gas vapour phase constituents in cigarette smoke enhanced abnormal growth and tumorigenicity in primary cultures of hamster lung cells regularly exposed over long periods to the smoke from one of three types of cigarette. The ultrastructure of such cells was investigated by electron microscopy. Cells from cultures exposed to low levels of gas vapour phase constituents resembled cells from control, non-exposed cultures, and were filled with secondary lysosomes of the autophagic vacuole type. These autophagic vacuoles contained dense particles similar in size to the nucleoids of certain viruses. Cells from cultures exposed to high levels of gas vapour phase constituents and cells from tumours formed in nude mice after subcutaneous injection of transformed cultures lacked autophagic vacuoles but contained a higher number of cytoplasmic microfilaments. R-type (equals H-type) virus particles were found in the ER cisternae of control and exposure cultures at all ages, whilst A-type virus particles were found in close association with mitochondria in a transformed, exposed culture and in control cells which also formed tumours in nude mice but only after a much longer culture period.