Cytologic structures unique to deiters cells of the cochlea

Abstract

Deiters cells in the gerbil cochlea disclosed unusual ultrastructural features. A sharp transition zone separated the cell body underlying outer hair cells into an upper compartment with numerous organelles and a lower part devoid of structures other than the microtubule stalk. Deiters cells exhibited a unique structure, the rosette complex, which consisted of a core of densely fibrillar trabeculae, enclosed in a filamentous meshwork and surrounded by tubulocisternal endoplasmic reticulum. The dense trabeculae radiated in columns downward from an apical translucent area toward a lucent zone around the nucleus. They also spread to the medial plasmalemma enveloping nerves and upward into the base of the phalanx. Frequent, small Golgi complexes bordered the tubular reticulum. The distinctive mitochondria of Deiters cells frequently paralleled the plasmalemma, revealed an elongated, often arched profile, and contained sparse, longitudinally aligned cristae. The stalk, composed of characteristic microtubule bundles resembling those in pillar cells, ascended from basal to apical plasmalemma of the cell body and into the phalanx and reticular lamina as previously described. The stalk appeared also to ramify into smaller microtubule bundles in apical cytosol penetrating the rosette complex. Nuclei in Deiters cells differed from those in hair cells in their location high in the cell and in showing chromatin dispersion indicative of more active protein synthesis.

Golgi-canalicular reticulum system in ion transporting fibrocytes and outer sulcus epithelium of gerbil cochlea

“…A similar association of CR with Golgi elements has been encountered in other sites including human eccrine sweat glands (Baron et al, 1984) and cochlear Deiters cells (Spicer and Schulte, 1993). Moreover, a striking development of Golgi cisternae takes place in Deiters cells and pillar cells of neonatal gerbils 14-15 days after birth, at the precise time when CR appears in these cells (Ito et al, 1995).…”

“…However, there is presently no knowledge that CR contains an ATPase or a protein kinase, either of which would utilize high energy phosphate for ion transport, and it is accordingly uncertain as to whether this system demands energy for its presumed function in facilitating ion flow. Moreover, the elaborate display of CR in other sites such as Deiters cells of gerbil cochlea and the human eccrine sweat gland lack an abundance of closely associated mitochondria (Spicer and Schulte, 1993;Baron et al, 1984). If mitochondria associated with CR energize ion movement in type II fibrocytes, the transport mechanism involved in this site must differ from that in Deiters cells and sweat glands.…”

Novel structures in marginal and intermediate cells presumably relate to functions of apical versus basal strial strata

“…R-OTO. perilymphatic K + , including ions effluxing from outer hair cells in the course of auditory transduction (Spicer and Schulte, 1993, 1994a,b, 1996, a silent current (Zidanic and Brownell, 1994) and a nonacoustic parallel current (Spicer et al, 2003). The morphologic data testified further that type II, IV and V fibrocytes relayed these currents to type I fibrocytes in spiral ligament on their way to basal cells of the stria (Spicer and Schulte, 1996;Spicer et al, 2003).…”

“…An arrangement of two structurally and therefore functionally distinct strata in a single cell is shared in the cochlea with inner and outer hair cells and Dieters cells (Spicer and Schulte, 1993;Spicer et al, 2003). Although apparently not encountered often outside the cochlea, a two-tier system offers the advantage of housing in the crowded cochlear epithelium two biologic specializations in the space of one and an uninterrupted secretory surface.…”

“…K + effluxing from outer hair cells (Ashmore and Meech, 1986;Gitter et al, 1986;Santos-Sacchi and Dilger, 1988;Santos-Sacchi et al, 1997) has been postulated to return to the stria transcellularly via a lateral recycling pathway (Spicer and Schulte, 1993, 1994a,b, 1996. In addition, a silent current recovers K + that diffuses extracellularly into scalae vestibuli and tympani (Zidanic and Brownell, 1994).…”