Cytochemical localization of acid phosphatases in the dimorphic fungusSporothrix schenckii

A modified Gomori procedure at the electron microscopic level revealed a multiplicity of acid phosphatase activity sites in both yeast-like and mycelial phase cells. Vacuoles and the periplasmic space contained electron opaque deposits (lead phosphate) that were absent in control incubations either lacking the substrate (-glycerophosphate) or fortified with an inhibitor (sodium fluoride). The outermost region of the cell envelope was also active and, in contradistinction to previous examples with other yeasts, deposition of lead phosphate in this locale occurred even when the rate of orthophosphate generation was drastically reduced by lowering the substrate concentration. When mechanically disrupted yeast-like cells were washed and then subjected to the cytochemical procedure, pieces of broken cell envelope gave a positive reaction. The reaction product was invariably restricted to one side of cell wall cross sections. A specific and novel association of acid phosphatase with a microfibrillar zone was indicated.