CYTOLOGICAL STRUCTURE OF CRYPTOCOCCUS NEOFORMANS

CYTOLOGICAL STRUCTURE OF ASPERGILLUS NIGER BY ELECTRON MICROSCOPY

“…Shatkin and Tatum(l6) previously indicated that the outer region of the cell wall of the filamentous Ascomycete, Neurospora crassa, consisted of a fibriform meshwork of great density, and in the cell wall interior a network of fibers, finer and less dense than those on the outer region, was discernible in the area where the wall usually appeared to be structureless. A fibrillar architecture of the whole cell wall has been reported on S. cerevisiae by Houwink and Kreger(7), C. neoformans by Tsukahara (20), and, subsequently, on T. mentagrophytes by the present authors (22). The cell wall of these fungi was found to be composed of fibrous and rather electrondense structures running longitudinally to the cell body.…”

“…Many workers (1)(2)(3)7,10,(13)(14)(15)(20)(21)(22)24) have regarded the fungus cell wall as a considerably thick-walled organelle which consists possibly of several layers. Similar findings were also obtained when most sections of the used strain of A. niger were treated with uranyl nitrate after permanganate fixation.…”

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“…In the case of a dermatophyte, however, potassium permanganate fixation did not always result in preserving the structural details of both organelles. Internal Double Membrane A double membranous structure, resembling the endoplasmic reticulum of animal cells, was also noted in several species of fungi (2,11,15,21,22). In certain dermatophytes, T. rubrum, the presence of a much-folded smooth membrane, which traverses the cytoplasm and is reminiscent of the endoplasmic reticulum of higher animals, has been reported (3,7,17).…”

“…The cytoplasmic membrane in certain fungus cells has been accepted as a thin single membrane which lies directly beneath the cell wall (2,15,21,22,24). In a study of the cytoplasmic ultra-structure of T. mentagrophytes, the presence of a single membrane was also demonstrated just beneath the cell wall ( Fig.…”

“…Accordingly, it must be confirmed by further studies with ever improving experimental methods that the cytoplasmic membrane in the dermatophyte has an unit architecture consisting of two dense layers separated by a light one. Nucleus A discrete nucleus of fungal cells has been found in certain yeasts (2,5,24,27,28), yeastlike fungi (15,21,22) and molds (9,20) by electron microscopy during the last decade. The existence of a nucleus in the dermatophytes, however, has been the most important subject of lively debate till just recent years.…”