Figure. a and b, histopathologic findings from infected frogs. Characteristic sporangia (s) containing zoospores (z) are visible in the epidermis (asterisk, superficial epidermis; arrow, septum within an empty sporangium; bars, 10 μm. c, Skin smear from infected frog, stained with 1:1 cotton blue and 10% aqueous potassium hydroxide (aq KOH) (D, developing stages of Batrachochytrium dendrobatidis; arrow, septum within a sporangium; bar, 10 μm. d, Electron micrograph of an empty sporangium showing diagnostic septum (arrow) (bar, 2 μm).