Ultrastructural aspects of hair digestion in black piedra infection

The study examined the ultrastructural pattern of human hair infection by the fungus Piedraia hortae, which caused black piedra. It was found that the fungus destroyed the cuticular layers and penetrated deeply into the hair cortex. Two distinct types of cortex digestion were identified, and the slow rate of keratin degradation, along with the compacted stromatic organization of the nodules, were suggested as reasons for the fungus's long survival and the chronic nature of the disease. The findings aimed to enhance understanding of the mechanisms regulating the pathogenicity of Piedraia hortae.