Mitochondria in living cells cultured from human chorionic villi: the effects of colchicine on numbers and distribution.

Fluorescence microscopy of living first trimester human placental cells and choriocarcinoma cells in cultures was carried out using the vital fluorescent dye Rhodamine 123. The length and distribution of mitochondria and, in the normal cells, their reaction to colchicine treatment is described. It appears that in the presence of colchicine the distribution of mitochondria in normal placental cells becomes more restricted to the perinuclear cytoplasm and that the mean length of mitochondria is reduced. However, the total length of all the mitochondria in treated cells is not significantly different from that in paired cells which were not exposed to the drug. It is inferred from this result that mitochondrial shortening in the presence of colchicine is not an elastic shortening consequent on the removal of cytoskeletal elements which promote extension of the organelle. Rather it is brought about by fragmentation of the organelle into tandem segments.