Induction and Ultrastructure of the Multicellular (Sclerotic) Morphology in Phialophora Dermatitidis

SUMMARYYeastlike cells of Phialophora dermatitidis were induced to form thick-walled, multicellular (sclerotic) bodies under very acidic culture conditions. Phase-contrast microscopy and conventional transmission electron microscopy of thin sections were used to demonstrate the development of these structures. Observations indicated that the multicellular bodies represented an intermediate vegetative growth form phenotypically arrested between the yeastlike and hyphal morphology. The suggestion is made that the acidic cultural conditions inhibited the event of bud emergence by the yeastlike cells without inhibiting the events of growth, nuclear division and cytokinesis.