| Photomicrographs |
Section: MICROORGANISMS
Subsection: FUNGI
Date Composed: 12-11-95 Date Modified: 12-18-95
FUNGI
Microscopic fungi are either unicellular (yeasts) or multicellular (Basidiomycetes or Fungi imperfecti). They are heterotrophic sporebearing organisms without chlorophyll. It is possible to view fungi microscopically without staining. However, staining with acid fuchsin or cotton phenol blue allows one to distinguish filamentous fungi from fibers and other nonmicrobiological deposits. Fungi often predominate in acidic environments but can live under neutral or alkaline conditions and in both liquid and only slightly humid environments.
There are four main groups of true fungi:
The Phycomycetes-nonseptate-asexual, sexual, no specialized structure for sexual spores
The Ascomycetes-septate hyphae
The Basidiomycetes-septate hyphae, clamp connections
The Deuteromycetes (Fungi imperfecti, septate hyphae-no known sexual spores)
Fungal spores may vary in size, shape, and color. The spores are usually involved in reproduction and spreading of the fungus. The fungal spore is a key characteristic used in classification of fungi. Most true fungi produce filaments called hyphae which form a network called the mycelium. If the hyphae have cross walls or septa defining the individual cells, they are called septate hyphae. The term coenocytic or nonseptate refers to the undefined cells in the filaments produced by the phycomycetes. Fungal hyphae and spores may not pick up the stain because of their inherent color and would have to be distinguished because of septate cells, branching, or other characteristics. Fungal hyphae are commonly larger in diameter than filamentous bacteria in addition to being branched.
Suggested method for slide preparation:
1) wet mount
2) phenol cotton blue
3) lactofuchsin