Pseudohyphal growth of C. gattii. (A) The C. gattii 97/433 strain exhibited pseudohyphal growth on filamentation agar. (B) Microdissected pseudohyphae of C. gattii cells continued to grow as pseudohyphae, unlike those of C. neoformans, indicating that inheritable genetic change(s) had occurred that promoted pseudohyphal growth. Scale = 10 μm. (C) The mutants always displayed pseudohyphal growth, even on rich YPD media, whereas wild-type cells grew as yeast. When washed, the pseudohyphae showed more invasive growth into the agar than wild-type cells on YPD media. The pseudohypha-forming mutants also exhibited temperature-sensitive growth at 37°C and were unable to proliferate.