COCHLEAR SYNAPTIC DEVELOPMENT AND MORPHOLOGY IN A GENETICALLY INDUCEDTYPE OF PROGRESSIVE HAIR CELL DEGENERATION

In mice with genetically induced inner ear abnormalities it is conceiv able that in the morphogenetic types and in mutants with the spotting kind of pigmentary anomaly, the genes act through the developing nervo us system. It has been suggested that in degenerative (neuroepithelial ) mutants the influence of the gene is also reflected in the inner ear through the agency of the nervous system. The jerker mouse belongs to the neuroepithelial type of mutants which in homozygotes results in e arly postnatal degeneration of the sensory epithelium of the inner ear , initially confined to the cuticular plate and the stereocilia. In sp ite of well-advanced hair cell degeneration, these mutants developed m orphologically normal afferent and efferent nerve terminals at cochlea r hair cells.