Comparative light and electron microscopic study of the auditory organs of two species of fishes (pisces): Hyphessobrycon simulans (Ostariophysi) and Poecilia reticulata (Acanthopterygii).
Hyphessobrycon simulans has a Weberian apparatus for transmission of sound energy to the auditory organ, whereas Poecilia reticulata does not. The fine structure of the auditory organs is identical in the two species. The better hearing - expressed by large bandwidth and high sensitivity - typical of the Ostariophysi - seems to be based exclusively on the presence of the Weberian apparatus. The sensory epithelium of the saccule and the lagena is made up of hair (sensory) cells and supporting cells. The vertically orientated macula sacculi is divided into a dorsal and a ventral cell area with oppositely arranged hair-cell kinocilia. The sagitta takes up the center of the saccule and shows only three small sites with connections to the otolithic membrane. Remarkably, the dorsal sensory cells are connected to the ventral part of the otolith, but the ventral cells are connected to the dorsal part. The macula of the lagena also comprises a dorsal and a ventral cell area with oppositely arranged hair cells. The sensory cells in all maculae are of type II. They exhibit a striking apical cell protrusion, the cuticular villus. It is partially fused with the kinocilium in the contact zones and joined to the otolithic membrane. The cuticular villus probably stabilizes the long kinocilia.
Hertwig
I
I
Institute of Zoology, University of Bonn, Germany.
Schneider
H
H
D000818:Animals; D004847:Epithelial Cells / Q000166:cytology; D005399:Fishes / Q000033:anatomy & histology*; D006198:Hair Cells, Auditory / Q000166:cytology; D006309:Hearing / Q000502:physiology*; D008854:Microscopy, Electron; D008858:Microscopy, Phase-Contrast; D011036:Poecilia / Q000033:anatomy & histology; D012444:Saccule and Utricle / Q000033:anatomy & histology / Q000166:cytology; D012679:Sense Organs / Q000033:anatomy & histology* / Q000166:cytology; D013045:Species Specificity