Origin and Development of Intrahyphal Hyphae in Sclerotinia fructigena

SUMMARYThe formation, development and subsequent exit of intrahyphal hyphae in S. fructigena have been studied by light and electron microscopy. This paper records for the first time how the wall of the intrahyphal hypha originates from a well defined vesicular zone localized between the parent plasmalemma and parent wall in a normal cell contiguous to a degenerated one within the hypha. For the first time, too, the occurrence of at least “intra-intrahyphal hyphae” is described here. Intrahyphal hyphae may branch one or several times and these branches may anastomose with one another. The intrahyphal hypha seems to exit from the parent one by mechanical breaking down of the wall of the latter.