FIG. 9.

Microscopic analysis of infected kidney tissue. Kidneys were excised from mice infected with the wild-type strain (DIC185) for 2 days or with the indicated rvsΔ mutant strain that were euthanized after 28 days of infection. (A) Kidney sections were analyzed by PAS staining. Kidney tissue infected with the DIC185 wild-type strain demonstrated a high level of penetration by hyphal filaments emanating from multiple sites within the cortex. In contrast, tissue infected with the mutant YLD14 (rvs161Δ) and YLD16 (rvs167Δ) strains showed large internal zones of fungal cells (indicated by arrows) that were completely surrounded by leukocytes (indicated by the arrowhead). Note that the zone of clearing within the fungal mass of the YLD16 (rvs167Δ) strain contained cells with a bud or pseudohyphal morphology. Images in the top panels were captured through a 4× lens, and the bottom panels were captured through a 60× lens. (B) Kidney homogenates were stained with calcofluor, treated with 1% KOH to help dissolve host tissues, and then examined by fluorescence microscopy.