The main ultrastructural properties of the gill epithelium of the zebrafish, Brachydanio rerio are investigated. The pavement cells are distinguished with their microvilli, infolding protrusions and construction of an intercellular channel system, while the chloride cells sited in filamental and especially respiratory lamellar epithelia are characterized by a high number of well developed, large mitochondria and an expansive, membranous tubular system. The close relationship observed between these cell types indicates that, at least ultrastructurally, chloride cells are communicated with the external milieu via the channel system of the pavement cells.

The main ultrastructural properties of the gill epithelium of the zebrafish, Brachydanio rerio are investigated. The pavement cells are distinguished with their microvilli, infolding protrusions and construction of an intercellular channel system, while the chloride cells sited in filamental and especially respiratory lamellar epithelia are characterized by a high number of well developed, large mitochondria and an expansive, membranous tubular system. The close relationship observed between these cell types indicates that, at least ultrastructurally, chloride cells are communicated with the external milieu via the channel system of the pavement cells.