Abstract
During studies of both saprobic and parasitic cycles of Coccidioides immitis, we found that the hyphae contained septa with simple pores, Woronin bodies, pinocytotic vesicles and/or lomasomes. The alternating thallic arthroconidia were released by fracturing of the adjacent sterile cells. The endospores were formed by progressive cleavage of the spherules. The taxonomic classification of C. immitis still remains obscure.