The structure of the mycelial wall of Agaricus bisporus.

The chemical composition of fractions extracted from the mycelial walls of Agaricus bisporus was studied. Attempts were made to locate these materials "in situ" by comparing electron micrographs of shadowed and sectioned cell walls. There are at least two chemically distinct species of carbohydrate polymers: one yielding mainly glucose with lower amounts of mannose, galactose and xylose and amino acids, and the other yielding chiefly N-acetylglucosamine with some glucose and amino acids. It was shown that none of these polymers constituted a completely physically distinct layer, but there do seem to be two regions at the outer and inner surfaces with apparently different properties. Materials which react with MnO4K to produce an electron-dense material are located throughout the wall, but tend to be concentrated in the outer and inner regions. It was shown that fibers constitute one important fraction of the original wall material.