Images represent analyses taken at a Zeiss Axiovert 40C inverted microscope and an Axiocamera MRC5 (Zeiss, Germany) of spheres observed with phase contrast while culturing of dissociated mouse or guinea pig cochleas, as indicated. Data shown was obtained with TGFα-supplemented medium. Similarly, otospheres cultivated in culture medium with bFGF presented the same pattern of self-renewal (not shown). All images are from passage-one cells, cultivated for one (1DIV) or four (4DIV) days in vitro. Arrows indicate otospheres. Scale bar 50 μm.