The formation of ultrastructural epithelial and subepithelial connective tissue changes in experimentally induced cholesteatomas in guinea pigs.

Histoacryl-induced cholesteatomas were produced in guinea pigs at the posterosuperior part of the external ear canal adjacent to the tympanic membrane. Semithin and ultrathin tissue sections were used to study primary formation of the cholesteatoma as well as the influence of the altered epithelium upon the bordering zone of connective tissue. Quantitative and qualitative tissue changes were analyzed by electron microscopy and showed degradation and new formation of collagen and activation of fibroblasts. Our findings are similar to those previously reported on human cholesteatomas and indicate that the bordering subepithelial tissue seems to be influenced through the basilar membrane.