Does the organ of Corti attempt to differentiate new hair cells after antibiotic intoxication in rat pups?
In the adult mammalian cochlea, post-injury hair cell losses are considered to be irreversible. Recent studies in cochlear explants of embryonic rodents show that the organ of Corti can replace lost hair cells after injury. We have investigated this topic in vivo during the period of cochlear development. Rat pups were treated with a daily subcutaneous injection of 500 mg/kg amikacin for eight consecutive days between postnatal day 9 (PND 9) and PND 16. During this period the organ of Corti is not fully mature, but hair cells are hyper-sensitive to aminoglycoside antibiotics. Scanning and transmission electron microscopy was used to evaluate morphological changes in the organs of Corti during the treatment and at different post-treatment periods, up until PND 90. A massive loss in outer and inner hair cells was observed at least as early as PND 14. A prominent feature in the apical part of cochleas at PND 21 and 35 was the transient presence of small atypical cells in the region of pre
