ULTRASTRUCTURAL OBSERVATIONS ON REGENERATING HAIR CELLS IN THE CHICK BASILAR PAPILLA FOLLOWING AMINOGLYCOSIDE OTOTOXICITY

Thepotentialforregenerationofhaircellsintheavianbasilarpapilla(cochlea)wasfirstsuggestedwhenCruzetaltl]demonstratedrecoveryofhaircellnumbersfollowingototoxicdruginsult.AtthesametimeCotancheandhiscollaboratorsLZ.saof)servedthathaircellstereociliawerereplacedfollowingacoustictraumaandattributedthistotheregenerationof.newhaircells.Morerecently,regenerationofhaircellsandsupportingcellsfollowingacoustictraumahasbeendemonstratedbyDANlabelingwithtritiatedthymidineinbothneonatalchicks(4]andsexuallym…

ULTRASTRUCTURAL OBSERVATIONS ON REGENERATING HAIR CELLS IN THE CHICK BASILAR PAPILLA FOLLOWINGAMINOGLYCOSIDE OTOTOXICITY

Newly hatched chicks were injected with so mg/(kg' d) of gentamycin sulfate (GM )for 10 days. After 18st injection, animals were killed on survival days 3,6 .9 and 12. The chick basilar papillae (BP) were observed by transmission electron microscopy (TEM ). The results sho've'Ithat regenerated hair cells were erupted to the hasal membrane surrace in the early phase. The cytoplasm of these regenerated hair cells was heavily stained an contained numerous mitochondria. Afterseveral days, stereocilia appeared. When stereocilis bundles were rormed and cuticular layer was integrated, hasal nerve terminals were round. The results suggested that regenerating hair cells 'veredirectly produced on the hasal membrane surface following gentamycin induced ototoxlcity and thenI,roliferated and developed Into mature normal hair cells.