Wheat kernels with visible Fusarium-damage, naturally infected, have been examined with histochemical techniques to observe mycelium growth inside kernels and change in kernels cells. Kernels infected with F. culmorum were found to be damaged more extensively, comparatively to those infected with F. graminearum, F. avenaceum and F. nivale/(Microdochium nivale). Growth of Fusarium mycelium was most abundant between pericarp and aleurone layer and alongside of scutellum. Mycelium colonized also endosperm and embryo--both plumula and radicula.

Histochemical examination of wheat kernels invaded by Aspergilli and Penicillia proved penetration of fungal mycelium into subaleurone and endosperm cells through aleurone layer cells. Walls of aleurone layer cells in invaded kernels were found to be thicker and split. Formation of spores in cleistothecia's in endosperm cells was found. The observation of kernels under a stereoscopic microscope was found to be a sensitive way to detect fungi invasion in cereal kernels.