Hyphal Emergence and Outgrowth of Allomyces macrogynus in Aerated Cultures

Abstract

Hyphal emergence was delayed in aerated cultures of A. macrogynus. Continuous observation of individual organisms revealed alternation of growth at the tip and at the base, including an incorporation of part of the primary rhizoid into the hyphal region. Electron microscopy of sections confirmed the deposition of additional wall during the stages of development of the base. These sections also showed changes in wall structure during growth, in particular a readily removable component of early walls. Nuclei were positioned just below the emerging tips at hyphal emergence and at branching. The apical zones of exclusion contained few, if any, vesicles and multivesicular bodies. In other regions the mitochondria were observed in close proximity to the plasmalemma.