Invasion process of Candida albicans to tongue surface in early stages of experimental murine oral candidiasis.

We analyzed the morphologic and microbiologic aspects of the process of adhesion and invasion in the early stages of Candida albicans oral infection in a murine system. ICR mice were anesthetized by intramuscular injection with chlorpromazine chloride and then orally inoculated by swabbing with the C. albicans yeast cells. Their tongues were resected 1-3h after inoculation, washed sequentially with a physiological saline and 0.25% trypsin-solution and then homogenized. The number of viable C. albicans cells on the tongue surface was counted and fround to increase from 1-3h after inoculation. Most of the Candida cells attached to the tongue surface were present in clusters, mainly located in the gaps between lingual papillae and were covered with a mucoidal substance. By 3h after inoculation, these clusters frequently formed mycelia and could not be easily detached from the tongue surface by trypsin treatment. Observation of SEM and histological sections stained by Fungiflora Y revealed that the Candida hyphae at 3h stretched out of the cluster and entered the tongues through the surface. These results indicate that Candida hyphae begin to invade the tongue surface within 3h after inoculation and suggest that the mucus-like substance covering these cells may have an important early role in the interaction between the Candida cells and the tongue mucosal epithelium.