Areas of spontaneously healed tympanic membrane are called ?

When a tympanic membrane heals spontaneously without grafting, perforation is closed by squamous epithelium before fibrous elements develop.The fibrous layer may be attenuated or even lacking.The resultant tympanic membrane has an area that lacks the tensile strength, elasticity, blood supply and resistance to future perforation of a fully reconstructed tympanic membrane.Such areas are called dimeric because the squamous epithelium lies against the mucous membrane without intermediate fibrous elements.