Scanning electron microscopic observations on the inner ear of the skate, Raja ocellata

Abstract

The inner ear of the skate, Raja ocellata, was examined by scanning electron microscopy. The otolithic membranes have a gelatinous component and an endogenous class of otoconia. Cupulae are reticulate in form. The morphology and polarization of sensory cell hair bundles are described for the various regions of the labyrinth, and are compared with published observations on other species. In the otolithic maculae, the more centrally located receptor cells generally have longer sterecolia than the peripheral cells. The hair bundles of the lacinia are similar to those of the central portion of the sacculus and differed from those of the rest of the utricular macula. Hair bundles in the peripheral regions of all maculae and cristae are similar. The polarization pattern of the utriculus is similar to that of teleosts, while that of the lagena is less clearly dichotomized. The receptor cells of most of the sacculus are oriented in a bivertical direction, with cells in the anterior portion, and a few in the posterior region, being aligned longitudinally. The significance of morphology and polarization with respect to the functions of the otolithic organs is discussed. The relationship of cell processes of the ampullary receptors to the cupula is briefly considered.

Diversity in Fish Auditory Systems: One of the Riddles of Sensory Biology

“…Among fishes, some exceptions to this shape and orientation pattern of the macula utriculi are found. In cartilaginous fishes, for example, the studies by Lowenstein et al (1964) and Barber and Emerson (1980) indicated that ciliary bundles with opposing orientation are interspersed in the radial orientation pattern of ciliary bundles on the cotillus ( Figure 5A). In addition, the macula utriculi of the lesser spotted dogfish Scyliorhinus canicula seems to lack a striola region (Lovell et al, 2007).…”

“…well as for cartilaginous fishes (Lowenstein et al, 1964;Barber and Emerson, 1980;Lovell et al, 2007). Most studies on macula morphology in Chondrichthyes focused on the macula neglecta in Elasmobranchii (Corwin, 1981(Corwin, , 1989Myrberg, 2001;Casper, 2011).…”

“…Mainly two vertical groups of ciliary bundles are present. In the anterior portion these vertically oriented bundles are brought into a new horizontal orientation by upwards curving of the macula in this region ( Figure 6B; Lowenstein et al, 1964;Corwin, 1981;Lovell et al, 2007; but see Figure 6A; Barber and Emerson, 1980).…”

“…The maculae in (E-H) stem from species that possess accessory hearing structures. Illustrations modified from Barber and Emerson (1980), Deng et al (2013), Mathiesen and Popper (1987), Platt (1977), Platt et al (2004), Popper (1978), Popper and Platt (1979), Popper and Tavolga (1981), and Schulz-Mirbach et al (2014). a, anterior;d, dorsal;lat, lateral. modified orientation patterns.…”

“…The rectangle in C indicates the striola region of the macula sacculi. Illustrations modified from Barber and Emerson (1980), Lovell et al (2005Lovell et al ( , 2007, Mathiesen and Popper (1987), Platt et al (2004), Popper (1978), and Popper and Northcutt (1983). a, anterior;d, dorsal. shaped and contains two main orientation groups.…”