Micromorphology of Conidiospores of Aspergillus niger by Electron Microscopy

Abstract

The fine structure of conidiospores of Aspergillus niger has been studied by means of ultrathin sectioning and electron microscopy. Permanganate fixation of the conidia preserved the details of their inner structural components and enhanced the general contrast within the sections. The conidiospores are characerized by their peculiar surface structures composed of three distinct components; an outer hull, a spore coat or wall, and an intermediate space. As a consequence of the swelling of the conidia, both the outer hull and the intermediate space almost completely disappear, and a variety of the intracytoplasmic organelles becomes visible in large numbers. The mature conidia at the resting stage appear to possess a more electron-dense cytoplasm than that of the parent hyphae of the organism. They also contain a nucleus and a few mitochondria within the cytoplasm. The significance of these structures and their relationship to the parent hyphal cells are discussed.