Morphology and cell type heterogeneities of the inner ear epithelia in adult and juvenile zebrafish (Danio rerio)

Although the zebrafish has become an important model for genetic analysis o f the vertebrate auditory system, a comprehensive description of the zebraf ish ear has been provided for embryonic and larval development only (Haddon and Lewis [1996] J. Comp. Neurol. 365:113). Here we describe the developme nt of sensory maculae in juvenile fish and the morphology of the adult zebr afish ear. This description was obtained via three-dimensional reconstructi on of serial sections and confocal microscopy of immunolabeled preparations and includes the Weberian ossicles and fluid spaces. Phalloidin staining, which labels actin filaments of stereocilia, was used to delineate the sens ory epithelia, to visualize the distribution of hair cells, to estimate the ir density in different areas of the maculae, and to perform hair cell coun ts. Morphology of ciliary bundles in different regions of the lagena, saccu le, utricle, macula neglecta, and cristae was characterized with an anti-ac etylated tubulin antibody and by phalloidin staining. We have identified tw o antibodies characterized by region-specific staining patterns in the inne r ear epithelia. Zn-1 antibody staining largely correlates with the presenc e of short-bundle hair cells in the peripheral regions of sensory epithelia . Zn-4 antibody, on the other hand, labels a zone of epithelial cells surro unding the sensory maculae. These analyses extend previous observations of cell-type heterogeneity in both sensory and nonsensory epithelia of the fis h ear. J. Comp. Neurol. 438:173-190, 2001. (C) 2001 Wiley-Liss, Inc.