Ultrastructural characteristics of Coccidioides immitis, a morphological variant of Cryptococcus neoformans and Podosypha ravenelii.

Electron microscopic examination of Coccidioides immitis revealed dense septum-associated bodies, characteristic of Ascomycetes. Similar examinations of a filamentous variant of Cryptococcus neoformans failed to clarify the taxonomic position of this yeast but did not exclude the possibility that this organism is a heterobasidiomycete. Septal pores were not seen in either organism.