A Study on the Normal Development of Tympanic Membrane of Mice

Abstract

A histological study was made of the normal development of the tympanic membrane of ddN mice from the twelfth day of gestation to 14 days after birth. The genesis and later development of the tympanic membrane is intimately related to the formation of the external auditory meatus. After reaching near the tubotympanic recess, the primitive external auditory meatus extends along the recess until terminating on the eighteenth day of gestation. From 1 to 7 days after birth, the organs peculiar to the internal and external sides of the primordium of the tympanic membrane develop, and on 8 days after birth, a separation occurs between the two sides. The side facing the external acoustic meatus moves toward the osseous or cartilaginous portion of the meatus as it expands, leaving the tympanic membrane which develops after birth.