The filamentous fungi of the genus Fusarium, Aspergillus and Penicillium produce lesions in the form of ulcers in the corneal layer of the gizzard. The pH of the zone is acidic and therefore suitable for the growth of these fungi. The lesions progress to Phase 2 and 3 coming to pierce this layer. The lesions are produced by fungi and can be simultaneous or not with the presence of mycotoxins.