FIG 1.

Illustration of compositional and morphological responses to the in vitro and in vivo environments discussed in the review. C. neoformans grown in RPMI for antifungal susceptibility tests lacks melanin in its cell wall, due to the absence of phenolic precursors in the medium, grows capsules 2 to 4 μm thick (45), and is not known to manifest as titan cells. Cells grown in vivo display melanized cell walls (20, 21) and grow capsules averaging 20 and 8 μm thick in lung and brain, respectively (37). Titan cells make up ∼20% of C. neoformans cells found in lungs and a smaller, but observable, portion of cells in the brain (50). Diagram was not drawn to scale.