Abstract
Numerous fungal organisms are dimorphic, exhibiting distinct morphological transitions in rcsponse to specific envirommental signals. Typicany, dimorphic fungi show either a unicellular yeast-like form or a filamentous form of attached cells. Recent investigations, including molecular genetics, on the dimorphic transitions in Saccharomyces cerevisiae and Candida yeasts have shown that the switch mechanism from the yeast-like form to the filamentous form is under genetic controls. Recent finldings of fungal dimorphic transitions have proven to be a simple model for understanding biological problems of morphogenesis and differentiation.