Ontogeny of lipid bodies in the endoplasmic reticulum of Fusarium sulphureum.

The ontogeny of lipid bodies during the differentiation of conidial cells to chlamydospores in Fusarium sulphureum (F. sambucinum f. 6) is described. The lipid bodies are first seen as electron-transparent areas within dilated cisternae of the endoplasmic reticulum (ER). One or more such cisternae may be formed within a strand of ER. The intracisternal lipid bodies are bounded by a unit membrane derived from the double membrane of the ER. The dilated cisternae increase in size and remain electron-transparent; however, some electron-dense granular material is present in the lipid bodies. The limiting unit membrane is visible throughout development of the lipid body; however, in mature chlamydospores the membrane is obscured by a broad band of electron-dense material which may provide protection to the stored lipids during adverse environmental conditions. The system of lipid body development in F. sulphureum is discussed in relation to those described for higher plants.