Demonstration of Myelin Figures in Unfixed, Freeze-etched Fungus Spores

With increased use of glutaraldehyde fixatives (15), membrane whorls of myelin figures have been noted in many tissues prepared for electron microscopy (e.g ., 3, 7, 9, 10, 14, 16, 17) . Some workers have considered them artifacts produced by glutaraldehyde fixation (5, 12, 13) . We observed myelin figures in glutaraldehyde-osmium tetroxide-fixed conidia of Scopulariopsis brevicaulis, a member of the Fungi Imperfecti, while following conidiogenesis (4) . This report describes studies undertaken to determine whether these myelin figures were artifactual .