The interactions between asbestos fibers and metaphase chromosomes of rat pleural mesothelial cells in culture. A scanning and transmission electron microscopic study.

Rat pleural mesothelial cells (PMCs) in culture at the exponential growing phase were exposed to 5 micrograms/ml of chrysotile (CH) or crocidolite (CR) asbestos fibers: the cells and their chromosomes were studied 48 hours thereafter by light, scanning, and transmission electron microscopy (LM, SEM, TEM). PMCs phagocytized both CH and CR. Mild vacuolar cytoplasmic changes by LM and a few small surface blebbings by SEM were present, mainly in cells treated with CH. Metaphase chromosomes were well separated and retained surface details by SEM in the control group. Chromosomes were frequently entangled with, adherent to, and severed or pierced by long and thin curvilinear CH with occasional chromatin fibers threading over the partly severed asbestos. Similar chromosomal changes were much less frequently found in CR-treated cells; TEM confirmed the same findings. CH and CR have different physicochemical properties and also appear to have direct, intricate, but different interactions with chromosomes, as well as the cytoplasm, of PMCs.