A kinetic study of the endolymphatic sac epithelial cells

The kinetics of S-phase (the period of DNA synthesis) cells in the endolymphatic sac (ES) was investigated by immunohistochemical methods. A monoclonal antibody against 5 bromo 2'-deoxyuridine (BrdUrd) was used. After administration of BrdUrd i.p., guinea pigs were sacrificed with acid formalin at designated survival times until 28 days, and the decalcified temporal bones were examined immunohistochemically. After survival for 30 min, scattered cells labelled with an anti-BrdUrd antibody were detected within the ES, whereas they were not found any other part of the inner ear. Labelled cells were observed more frequently in the rugose portion than in the other portion of the ES. At 3 days after BrdUrd labelling, increased numbers of labelled cells were detected. Labelled mitoses could be observed in the epithelium after long survival times. Our results show that the epithelial cells of the ES in adult animals turn over in the steady-state.