FIG. 3.

PAS-stained paraffin sections of lung tissue harvested from mice 14 days after infection with H99. Cryptococci were evident as strongly PAS-positive round cells (black arrows), often surrounded by a capsule and occasionally budding (blue arrows). (A) Although the alveolar structure of the lung (L) could be identified in many sites, this was lost in areas containing large numbers of extracellular cryptococci, which apparently caused tissue destruction (D). Major structures such as bronchioles (B) were often retained. (B) At a higher magnification of areas showing tissue destruction, occasional cryptococci within blood vessels (V) were noted. (C) Areas of granulomatous reaction (Gr) containing organisms within epithelioid macrophages and Langhans-type giant cells were also seen (red arrows). (D) At a higher magnification, budding cryptococci (blue arrows) were noted in some giant cells. Bars = 150 μm for panels A and C and 60 μm for panels B and D.