Cytological aspects of dimorphism in Candida albicans.

From a comparison of the growth of yeast and hyphal cells of Candida albicans at 37 degrees C, the present authors suggest that the formation of hyphae is a response to nutrient stress. The major cytological evidence for this is that the formation of a germ tube is chiefly the result of the migration of cytoplasm out of the parent yeast cell, with little biosynthesis occurring other than DNA replication and wall assembly. This explains the linear outgrowth of the germ tube rather than an autocatalytic outgrowth. It is accompanied by the enlargement of the vacuole in the parent cell. Subsequent elongation of the hyphae is accompanied by vacuolation of subapical compartments, and branching only occurs from some of the subapical compartments after they have reformed sufficient cytoplasm.