Mycelial Filaments Research Articles

Experimental phaeohyphomycosis

The authors performed an experimental infection of the rabbit eye with Wangiella dermatitidis which had been isolated from the corneal ulcer of a patient. The fungus was inoculated into the front chamber and the vitreous body. The disease showed a trend to spontaneous recovery. The individual phases of the experimental infection were followed by histology and electronmicroscopy, both TEM and SEM. Different stages of development of the polymorphous fungus, as sclerotic bodies, mycelial filaments and yeast-like cells, could be demonstrated.

Conidial repression by phenethyl alcohol and its serological consequences in Neurospora crassa.

Phenethyl alcohol (PEA) at concentrations ranging from 0.04 to 0.08% (v/v) repressed conidial differentiation (C) and its associated carotenogenesis in wild type neurospora crassa. With 0.16–0.32%, most of the conidia germinate into swollen, yeast-like cells (Y) producing buds instead of mycelial filaments (M). Incubation with PEA increased alcoholic fermentation and sharply reduced the immunoelectrophoretic diagram. The step-wise reduction of Neurospora morphogenesis (C→M→Y) reveals the trimorphic potentiality of its hyphal system.

Culturing and embedding of filamentous fungi for electron micrography in the plane of the filaments.

One-day-old mycelia of Volvariella volvacea, grown on water-permeable cellophane membrane applied to an agar medium, were stripped from the medium and fixed 1 hr in 3% glutaraldehyde followed by 2 hr in 1% OsO4. The specimens were washed in water, dehydrated with acetone and embedded in Vestopal W. The flat end of the precast tissue carrier was placed on the top (tissue side) of the specimen in a polyethylene dish. The preparation was first allowed to harden 12 hr at 50 C. After hardening was completed at 60 C., the block was removed, the cellophane stripped off, and the face of the block trimmed for sectioning. Since the mycelium had grown as a thin flat layer, the face of the block required little or no trimming, and sections in the plane of the mycelial filaments were readily obtained.

Chronic, destructive, mucocutaneous phycomycosis in man.

A case of mucocutaneous phycomycosis, localized in the face and neck, of 24 years duration, with destruction of the soft tissues of the nose, palate and lips, is described. A granulomatous, chronic inflammatory process, associated with abundant mycelial filaments was observed. On four occasions cultures of biopsy samples yielded the same fungus which Hesseltine & Ellis (1964) regard as Mucor ramosissimus Samutsevitsch. Treatment with amphotericin-B was apparently successful.

The Occurrence of Arachniotus Citrinus in Soils

Arachniotus citrinus was first described by Massee and Salmon in 1902 (3). This member of the family Gymnoascaceae was observed growing on kangaroo dung collected in the London Zoo. Morphological studies were made on the gross specimen only, as cultivation of the fungus on synthetic media was not attempted. Since that date no fur? ther observations of this ascomycete have been reported. Recently, while a large number of Tennessee soil samples were being screened for the presence of Histoplasma capsulatum and Microsporum gypseum, two soil samples yielded A. citrinus. One isolate was recov? ered indirectly from soil by passage through mice (2), while the second was observed developing adventitiously on strands of sterilized human hair used as bait for isolation of M. gypseum (1). A. citrinus grew readily on Sabouraud dextrose agar, forming a white cottony colony which slowly turned lemon-yellow 3 in color as asci and ascospores were developed. On Czapek's agar mycelial development was sparse but numerous lemon-yellow clusters of asci were formed. There was scant production of mycelium on sterilized rabbit dung pellets and rabbit dung extract agar (Fig. 1A). However, this medium was excellent for inducing ascus formation. Microscopic examination of the fungus grown on all these media revealed essentially similar findings. It was noted that copulation branches arose from mycelial filaments and coiled about each other (Fig. 1B). From these copulation branches asci were successively developed (Fig. 1C). This successive development of asci from the copulation branches led to the formation of clusters of asci along the hyphae (Fig. ID). No signs of a peridium were found. Each ascus enclosed eight elliptical, smooth, lemon-yellow spores (Fig. ID). When mounted in

The Morphology of Sporothrix Schenckii in Tissues and in Artificial Media

A point of some interest in connection with the study of fungi of various kinds is the difference that appears in the morphology of the organisms when growing in the living tissues and when growing on artificial media. The variations, for example, of actinomyces and blastomyces in this respect are well-known phenomena. Similar observations on sporothrices have also been observed and it is the purpose of this paper to inquire further into this matter with a view to determining under what conditions such variations in morphology occur. In living tissues spoI'othrix organisms always appear as elongated or oval bodies fairly uniform in size and often showing distinct budding processes (Fig. i). The arrangement is usually single, but frequently two or more are found end to end, and at times several may be arranged radially about a central spore. In experimental sporotrichosis as a rule these forms are numerous in the tissues and easily stained. In the human body they may at times be present in large numbers but usually they are so few in number that it is difficult or impossible to find them. For convenience I shall call these forms, tissue forms. Branched mycelial filaments are not found in the living tissues either in the human or the experimental disease. These mycelial threads or hyphae develop abundantly on practically all the artificial media that have been used and at their sides and extremities