Progenitor cell cycling during hair cell regeneration in the vestibular and auditory epithelia of the chick.
We investigated nucleotide-labeling patterns during ongoing hair cell regeneration in the avian vestibular epithelium and during drug-induced regeneration in the avian auditory epithelium. For utricle experiments, post-hatch chicks received an injection of bromodeoxyuridine (BrdU) and were allowed to survive from 2 hours to 110 days after the injection. Utricles were fixed and immunoreacted to detect BrdU. The number of BrdU-labeled nuclei in the hair cell and support cell layers of the utricular sensory epithelium changes significantly between 2 hours and 110 days post-BrdU. At 2 hours, most labeled cells are isolated, while by 5-10 days, the majority of labeled cells are organized in pairs that are most frequently composed of a hair cell and a support cell. Pairs of labeled cells are seen as late as 110 days. Clusters of more than 3 labeled cells are uncommon at all time-points. The total number of labeled cells increases approximately 1.5-fold between 5 and 60 days post-BrdU. This increase is due primarily to a rise in the number of labeled support cells, and it is likely that it represents additional rounds of division by a subset of cells that were labeled at the time of the BrdU injection. There is a significant decrease in labeled nuclei in the hair cell layer between 60 and 110 days post-BrdU, suggesting that hair cells die during this period. To investigate support cell recycling in the drug-damaged auditory epithelium, we examined nucleotide double labeling after separate injections of BrdU and tritiated thymidine. A small number of support cells that incorporate BrdU administered at 3 days post-gentamicin treatment also label with tritiated thymidine administered between 17 and 38 hours later. We conclude that a small population of support cells recycles during regeneration in both the normal utricle and the drug-damaged basilar papilla.
Stone
J S
JS
Virginia Merrill Bloedel Hearing Research Center, University of Washington, Seattle, Washington 98195, USA.
Choi
Y S
YS
Woolley
S M
SM
Yamashita
H
H
Rubel
E W
EW
D000818:Animals; D001973:Bromodeoxyuridine / Q000494:pharmacology; D002452:Cell Count / Q000187:drug effects; D002467:Cell Nucleus / Q000187:drug effects; D002645:Chickens; D004847:Epithelial Cells / Q000166:cytology* / Q000187:drug effects; D005839:Gentamicins / Q000494:pharmacology; D006198:Hair Cells, Auditory / Q000166:cytology* / Q000187:drug effects / Q000502:physiology*; D007760:Labyrinth Supporting Cells / Q000166:cytology / Q000187:drug effects; D012038:Regeneration / Q000187:drug effects; D013234:Stem Cells / Q000166:cytology* / Q000187:drug effects; D013936:Thymidine; D014316:Tritium; D014722:Vestibule, Labyrinth / Q000166:cytology* / Q000187:drug effects / Q000502:physiology
D005839:Gentamicins; D014316:Tritium; D001973:Bromodeoxyuridine; D013936:Thymidine