ABSTRACT
This chapter aims to document the range of cell shapes encountered in yeasts and describes the various modes of vegetative reproduction as they reflect on envelope morphology. Cell shape is sometimes useful as a taxonomic criterion; the pyramidal-shaped cells of Trigonopsis and the lemon-shaped cells of Hanseniaspora are spectacular examples. Monopolar budding may be restricted to the genus Pityrosporum. Other pathogenic yeasts undergo vegetative reproduction by multipolar budding. Bipolar budding refers to the production of buds at two loci only. Vegetative reproduction by sterigmata is restricted to the genus Sterigmatomyces, this genus includes several species of which two were isolated from marine sources; they form neither classical buds nor true mycelium. Species of Schizosaccharomyces and Endomyces exhibit vegetative reproduction by fission alone. A primary distinction may be made among species in their tendency to form true mycelium or pseudomycelium. Some fungi, which tend to stabilize in the mycelial phase, also exhibit yeastlike growth under special conditions.
