Electron Microscopic Observation of the Sporangial Structure of an Actinomycete, Microellobosporia flavea

Abstract

Ultrathin sections of sporangia of the actinomycete Microellobosporia flavea were examined with an electron microscope. The sporangial wall is a thin wrinkled membrane which seems to be an extension of the outer layer of the cell wall of the sporangiosphore. A substance (probably a liquid) is located between the sporangial wall and the sporangiospores. The spores are ovoid and consist of a laminated wall in which two layers can be differentiated. The wall is 30-40 m[mu] thick but thickens to 90-120 m[mu] at the point of contact between two spores. Inside the spores one can differentiate a finely granular nucleus, large vacuoles which are probably filled with a fatty substance and a coarsely granular cytoplasm. The cytology of the sporangiospores of M. flavea is similar to that of the conidia of Waksmania rosea.