Microbodies were observed in the hyphal tips of all 14 fungi investigated. Their morphology varied among the fungi and their numbers were influenced by the growth medium. Microbodies were closely associated with mitochondria in one fungus and with the endoplasmic reticulum in several fungi. Catalase was not detected in microbodies with the diaminobenzidine cytochemical procedure even though catalase activity was present in extracts of these fungi. The activities of the glyoxylate-cycle enzymes isocitrate lyase and malate synthase were affected by the growth medium and were particulate in the two fungi studied by differential centrifugation. Microbodies are abundant, and they are ubiquitous among the fungi and in some cases they may contain glyoxylate-cycle enzymes.

1970. Microbodies and lipid bodies in the hyphal tips of Sclerotitzia sclevotiorum. Can. J. Bot. 48: 1689-1691.Hyphal tips of Sclerotit~ia sclevotiorrtm grown on a carboxymethylcellulose agar medium were studied with interference contrast, phase contrast, and dark-field optics and with the electron microscope. Microbodies with hexagonal crystalline inclusions were most abundant in a zone 80-160 p from the hyphal apex. It is suggested that these bodies are involved in synthetic and storage functions. Lipid bodies were identified by their fluorescence with Nile blue and by their refractivity using dark field optics. They were most abundant in the first 80 p of the hyphal tip and are thought to originate in this zone. Nuclei were randomly distributed throughout the hyphal tip cell.

The possible functional role of vesicles and crystal-containing microbodies in the production of oxalate, endopolygalacturonase, or cellulase by Sclerotinia sclerotiorum was investigated. The presence of multivesicular bodies in hyphal tips was not correlated with secretion or production of oxalate or these extracellular hydrolases. More crystal-containing microbodies were present in hyphal tips grown on media which supported greater extracellular enzyme production. No correlation existed between numbers of crystal-containing microbodies in hyphal tips and production of oxalate. Numerous membrane-bound vesicles (0.09–0.18 µm diam) were associated with tips grown on a D-glucose–Na succinate medium which supported high production of oxalate. The general ultrastructural organization of these hyphal tips was similar to that reported for other ascomycetes. Differences in numbers and distributions of organelles were observed between hyphal tips and older hyphae as well as between hyphal tips grown on the different carbon sources.

A lysosomal system was demonstrated in hyphal tip cells of Sclerotium rolfsii by light and electron microscopy observations of the sites of acid phosphatase activity visualized by a modified Gomori lead nitrate method. The cytochemical reaction product was found to be present in numerous vacuoles, each aout 0.5 ,um in diameter, which were seen as chains of spheres when viewed with the light microscope. They usually did not occur in the first 30 to 40 ,um of the hyphal tip cell, but were concentrated in a zone extending from 30 to 200 ,tm from the hyphal apex. As shown by the electron microscope, the vacuoles were sometimes interconnected by narrow channels. Acid phosphatase reaction product was also occasionally localized in vacuoles of the older hyphal cells, but never in apical vesicles, lipid bodies, or microbodies. It is proposed that this vacuolar system may originate from the endoplasmic reticulum.