Fine cytochemical detection of acid mucopolysaccharides in growing hyphae of Neurospora crassa.

The presence of mucopolysaccharides (MP) in Neurospora crassa hyphae was detected in samples of cultures from 4 h to 5 days. Using a modification of the method of Rothman (1969), acid MP were identified by electron microscopy in vesicles located at the apex, septae, and throughout the cytoplasm of the hyphae. The size, number, and localization of these vesicles was related to the stage of growth of the fungus. The mechanisms of release and transport of these macromolecules are compared to the process of secretion in cells endowed with a better developed endoplasmic reticulum and Golgi system. The specificity of the method was evaluated histochemically. The structures displaying greater electron density corresponded to the Alcian blue positive areas.