L'organe de corti chez la souris Swiss/RB

Abstract

Two groups may be distinguished in strain Swiss/RB mice: ‘susceptible’ group, with epileptic seizure when exposed to an intense sound, and ‘resistant’ group, without any audiogenic seizure. Both groups have a hearing impairment but are not completely deaf. Audiogenic susceptibility comes from a genetical origin, due to a recessive gene. The electron microscopic examination of the organ of Corti, performed in 6-week-old animals, does not show any essential difference between the two groups: (a) All the outer hair cells exhibit evidence of degeneration, though at different stages; (b) the inner hair cells seem normal; (c) the efferent nerve endings are relatively preserved but the afferent nerve endings as well as all the fibers, afferent or efferent, are very scarce.

From a cytological point of view, those changes look like an enzymatic disturbance, from a genetical origin, with a hindrance of protein synthesis in the site of hair cells and neurons. Is the hair cell degeneration induced by nervous degeneration, or is the involvement quite concomitant in both sites? Further studies will be necessary to resolve this problem. The histological and cytological data allow comparisons with some strains of patholgic mutants and give an approach to the study of inherited deafness in man.

Key Words:

• Auditory genetics
• Audiogenetic susceptibility
• Recessive gene
• Histopathology
• Cochlear microphonic