The size, density, and relative area of chromatic granules ("hydrogenosomes") in Trichomonas vaginalis Donne from cultures in logarithmic and stationary growth.

Electron micrographs of Trichomonas vaginalis cells were examined morphometrically by means of an electronic image analyser. Cells from cultures in logarithmic growth contained smaller chromatic granules ("hydrogenosomes") and a higher proportion of sausage- or dumb-bell-shaped granules than did cells in stationary growth. These findings support the view that chromatic granules replicate by division of pre-existing granules and that this involves elongation and attenuation of their mid-region. The total area of cross sectioned granules occupied the same percentage of the cytoplasm of cells from cultures in logarithmic and stationary growth. The density of chromatic granules in the cytoplasm was identical for the two groups of cells.