Ultrastructure and localization of wall polymers during regeneration and reversion of protoplasts ofSchizophyllum commune

Summary Cell-wall regeneration and reversion of protoplasts ofSchizophyllum commune were investigated using electron microscopic methods and X-ray diffraction.After 3 hours of regeneration protoplasts have formed a loosely organized wall which does not react with Thiéry's stain for periodic acid sensitive carbohydrates. This wall largely consists of chitin microfibrils which are adpressed to the plasmalemma and which are covered by loose aggregates of alkali-soluble S-glucan (-1,3-glucan). Both components are microcrystalline, at least partly. Walls formed in the presence of polyoxin D only consist of thick loose fibers of S-glucan.From 3 hours onward the inner chitin microfibrils of the wall of the primary cells become embedded in alkali-insoluble material that stains heavily with the Thiéry reagent and probably is similar to the R-glucan of the mature wall (i.e., -1,3--1,6-glucan). The outer chitin microfibrils remain free of this matrix and are covered by S-glucan only.Bud-like structures that arise have the same wall architecture as the primary cells,i.e., only the inner chitin microfibrils are embedded in R-glucan and the S-glucan forms a fluffy coat. The walls of hyphal tubes that arise are distinct, however, in that all chitin microfibrils are embedded in R-glucan and the S-glucan forms a compact coat.Cytoplasmic vesicles are sparse in primary cells except at the sites of emergence of budlike structures and hyphae. They continue to be present in the apex of growing hyphae.