Fine Structure of Fungi as Revealed by Electron Microscopy

Abstract

Summary 1. The cells of yeasts and filamentous fungi are surrounded by a cell wall. The cytoplast is bounded by a plasmalemma and contains nuclei, mitochondria, food granules and vacuoles. 2. Cell walls of vegetative fungal cells usually possess a microfibrillar ‘skeleton’, architecturally similar to that of plants, but composed of chitin or hemicellulose. True cellulose predominates only in the Oomycetes. Spore walls are often differently constructed from those of vegetative cells of the same species. 3. The cell contents (plasmalemma, endoplasm and endoplasmic reticulum, nucleus, mitochondria, vacuoles and miscellaneous granular inclusions), as seen in sections and in centrifuged material, are in general similar to those of plants. Some minor differences are indicated. The structure of the flagella of motile cells of the Lower Fungi is fundamentally similar to that of the flagella of lower plants and animals. 4. The electron microscope has contributed to our knowledge of growth and development of fungal structures. It has extended previous knowledge of the process of budding in yeasts, of the development of haustoria and of the formation and germination of fungal spores. 5. Poor nutrition, anaerobic conditions and sublethal irradiation cause abnormalities in the structure of mitochondria. Toxic amounts of irradiation prevent normal nuclear division in budding yeast cells. 6. Electron microscope studies have aided taxonomy by demonstrating fundamental structural differences between Fungi and Actinomycetes and between certain subdivisions of the fungi.

Observations on the Mycorrhizas of Forest Trees. II. The Rhizosphere of Pinus Radiata D. Don

“…Hawker 1965) have noted that few studies of the surface of fungi are reported in the literature. As far as we are aware no details of surface sculpturing offungal hyphae have been published.…”

“…In the mycorrhizas it was obvious that only the middle lamella substance is attacked and it is significant that the microfibrils of the host walls were revealed on maceration but not those of the fungi. Hawker (1965) has drawn attention to the meagre information about the chemical composition of the various fractions of the fungal cell wall. It is known that the fungal wall contains up to 40% of hemicelluloses (70% in yeast) (Roelofson 1959), and these are probably different to those of the host wall.…”

“…It is known that the outer surface of fungal hyphae are covered with an amorphous layer (Aronson and Preston 1960;Parker, Preston, and Fogg 1963;Hawker 1965), and that below this there is a microfibrillar layer of chitin or cellulose (Hawker 1965), or both (Fuller and Barshad 1960). Aronson and Preston described the wall in certain Phycomyces as having randomly arranged and intertwining microfibrils at the surface, as in the present case.…”

Surface Ultrastructure of Oidia in the Basidiomycete Psathyrella coprophila

“…All the oidia contained at least one prominent inclusion which was also visible in the light microscope. These inclusions were probably lipid structures of the type referred to by Hawker (1965).…”

ULTRASTRUCTURE, PROTOPLASMIC STREAMING, GROWTH AND TROPISMS OF PHYCOMYCES SPORANGIOPHORES

“…Studies of the ultrastructure of fungi have been reviewed by Hawker (1965) and Moore (1965). There does not appear to have been any previous examination of sections of Phycomyces sporangiophores by electron-microscopy, although the structure of the sporangiophore wall has been investigated in electron-microscope preparations and by a variety of biophysical techniques; these researches have been summarized by Preston (1952) and Roelofsen (1959).…”