Image Description
Microbiology: Coccidioides consist of two morphologically identical species - Coccidioides immitis and Coccidioides posadasii. The dimorphic fungus occurs as filamentous mycelia in its natural environment in the soil (saprobic phase) and develops endospores/spherules at body temperature in the mammalian host (infectious or parasitic phase). This image is from a case of splenic coccidioidomycosis. On the right side, there are several thick-walled, refractile immature spherules. On the lower left is a mature spherule, about 100 μm in diameter and containing several endospores measuring 3-5 μm in size.