THE ULTRASTRUCTURAL BASIS OF HYPHAL GROWTH

Abstract

Two vesicular systems associated with wall synthesis have been observed in Phycomyces blakesleeanus, Fusarium culmorum and Coprinus lagopus; these fungi have chitin in their walls. A system of vesicles produced by the endoplasmic reticulum is believed to be responsible for ‘primary’ wall synthesis. These vesicles fuse with the plasmalemma. Multi‐vesicular bodies from which lomasomes are formed are also produced by the endoplasmic reticulum; these are seemingly associated with ‘secondary’ wall synthesis, and it is suggested that they may be concerned with chitin deposition in the wall. Pythium ultimum, which has non‐chitinous walls, lacks multi‐vesicular bodies. Structures which have some features in common with lomasomes are present in Coprinus lagopus and Pythium ultimum, but they are postulated to arise by elaboration of the plasmalemma. Copyright © 1967, Wiley Blackwell. All rights reserved