Hair Cell Orientation Patterns in Fish Saccules
These figures demonstrate
hair cell orientation patterns that are found in the ear of fishes.
The top figure shows the ciliary bundles on the saccule of a lizard
fish. Each ciliary bundle contains a single kinocilium at one end
of the bundle and a larger number of stereocilia. The dashed line
in this scanning electron micrograph separates ciliary bundles that
are oriented with the kinocilium to the top (left) with those oriented
towards the bottom (right). The bottom figure illustrates a variety
of different saccular hair cell orientation patterns from different
drawing on the right shows the saccular hair cell orientation patterns
that we have identified in different fishes. The dashed lines show
the dividing lines between orientation groups while the arrows indicate
the location of the kinocilum (and thus the orientation) of most
of the hair cells in each region of the epithelium (or macula).
The 'standard' pattern is found in most species that are hearing
'generalists', or species that don't have any specilaizations for
hearing. The other patterns are found in a variety of fish species
that have specializations to enhance hearing capabilities. The patterns
are not necessarily taxonomically related, and the same pattern
may be found in taxonomically diverse species. For example, the
'vertical' pattern is found in all otophysan fishes (goldfish and
relatives) and also in the unrelated mormyrids.