Abstract
Volvariella volvacea (Bull. ex. Fr.) Sing. is a fungus of the tropics and subtropics. The changes in ultrastructure from the growing apex to the proximal part of a single hyphal cell could be distinguished not only by the distribution of cellular organelles but also by the electron density of cytoplasmic matrix, although the definite demarcation of the zone was impossible. The apical zone is characterized by abundant small apical vesicles. Mitochondria are clustered in the transitional region. The subapical zone is rich in a variety of cytoplasmic organelles including the nuclei. Towards the proximal region ageing proceeds and density of cytoplasmic matrix decreases. The cytoplasmic vesicles with dense granules found in both subapical and aged regions are considered to be formed either from the bulging cisternae of endoplasmic reticulum or from a system of cisterna membranes. The vesicles often broke from their limiting membranes and released their dense contents into the cytoplasm. They were also fused with vacuoles as well as with plasma membrane. Although the chemical nature of these vesicles is not known, their possible functions are discussed.
