The fine structure of spiral ligament cells relates to ion return to the stria and varies with place-frequency

doi:10.1016/0378-5955(96)00106-2

Hearing Research

Volume 100, Issues 1–2, October 1996, Pages 80-100

https://doi.org/10.1016/0378-5955(96)00106-2 Get rights and content

Abstract

Ultrastructural analysis of cells in the cochlea's lateral wall was undertaken to investigate morophologic features relevant to the route of K⁺ cycling from organ of Corti (OC) to stria vascularis (StV) and to the question of a transcellular versus an extracellular path. The fine structure of outer sulcus cells (OSCs) evidenced their capacity for uptake of K⁺ from Claudius cells and from perilymph in inferior spiral ligament. Plasmalemmal amplification and mitochondrial density together with known content of Na,K-ATPase testified to activity of type II, IV and V fibrocytes in resorbing K⁺. Location and fine structure afforded a basis for distinguishing subtypes among the type I, II and IV cells. The type 11, IV and V fibrocytes can be viewed as drawing K⁺ from surrounding perilymph and from OSCs and generating an intracellular downhill diffusion gradient for K⁺ flow through gap junctions to subtype Ib and la fibrocytes and strial basal cells. Pumping action enabled by extreme structural specialization of type II fibrocytes is considered to mediate K⁺ translocation across the interruption between the gap junction connected epithelial and gap junction connected fibrocyte systems and to explain ion flow directed toward StV through OSCs and fibrocytes despite their lack of polarity. The OSC bodies shrank, their root bundles expanded and the gap junction contact between OSCs and Claudius cells increased toward the base of the cochlea. Expanding root bundles and type I and IIb fibrocyte populations contrasted with shrinking OHCs and Deiters and tectal cells from the apex to the base of the cochlea. These differences indicated an increased magnitude and alternate route of K+ transport toward the StV in high as compared to low-frequency regions. The augmented K⁺ transport through spiral ligament in basal cochlea correlates with and provides a possible basis for the larger endocochlear potential in the base. The findings appear consistent with current flow extracellularly through scalae tympani and vestibuli and transcellularly through OC, OSCs and class I, II, IV and V fibrocytes.

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Research paperThe fine structure of spiral ligament cells relates to ion return to the stria and varies with place-frequency

Abstract

Intern. Rev. Cytol.

Hear. Res.

Hear. Res.

Hear. Res.

J. Ultrastr. Res.

Hear. Res.

Hear. Res.

Hear. Res.

Hear. Res.

Hear. Res.

Hear. Res.

Hear. Res.

The ultrastructure of the external sulcus in the guinea pig cochlear duct

Laryngoscope

An electron microscopic study of the function of the root cells in the external spiral sulcus of the cochlea

Acta Otolaryngol.

Submicroscopic structure of the membranous labyrinth. Ill. The supporting structure of Corti's organ (basilar membrane, limbus spiralis and spiral ligament)

Z. Zellforsch.

Basilar membrane, spiral limbus and spiral ligament

Intercellular junctions in the organ of Corti as revealed by freeze fracturing

Acta Otolaryngol.

Über das ‘Wurzelepithel’ des Ligamentum spirale der Schnecke

Folia Anat. Jpn

Gap junctions in the rat cochlea: immunohistochemical and ultrastructural analysis

Anat. Embryol.

Sensory and accessory epithelia of the cochlea

Ion transport in guinea pig cochlea. I. Potassium and sodium transport

Acta Otolaryngol.

Research paper
The fine structure of spiral ligament cells relates to ion return to the stria and varies with place-frequency