Apical Organization in the Somatic Hyphae of Fungi

Abstract

SUMMARY: By using phase-contrast microscopy a ‘Spitzenkörper’ was seen at the hyphal apex of all the ‘septate’ fungi examined, but none was seen at the apex of any Phycomycete. The spitzenkörper accepts staining with cationic dyes. A method is described for consistently obtaining ultra-thin sections longitudinally through hyphal apices. Electron micrographs indicate that the spitzenkörper is an aggregation of vesicles just beyond the apex, namely at the region where wall-formation occurs during extension growth. It is suggested that the vesicles are formed posteriorly and migrate to the apex where they fuse with the plasma membrane liberating their contents as part of the process of wall growth.