Large basolateral processes on type II hair cells are novel processing units in mammalian vestibular organs.
Sensory receptors in the vestibular system (hair cells) encode head movements and drive central motor reflexes that control gaze, body movements, and body orientation. In mammals, type I and II vestibular hair cells are defined by their shape, contacts with vestibular afferent nerves, and membrane conductance. Here we describe unique morphological features of type II vestibular hair cells in mature rodents (mice and gerbils) and bats. These features are cytoplasmic processes that extend laterally from the hair cell base and project under type I hair cells. Closer analysis of adult mouse utricles demonstrated that the basolateral processes of type II hair cells vary in shape, size, and branching, with the longest processes extending three to four hair cell widths. The hair cell basolateral processes synapse upon vestibular afferent nerves and receive inputs from vestibular efferent nerves. Furthermore, some basolateral processes make physical contacts with the processes of other type II hair cells, forming some sort of network among type II hair cells. Basolateral processes are rare in perinatal mice and do not attain their mature form until 3-6 weeks of age. These observations demonstrate that basolateral processes are significant signaling regions of type II vestibular hair cells and suggest that type II hair cells may directly communicate with each other, which has not been described in vertebrates.
The Virginia Merrill Bloedel Hearing Research Center, and the Department of Otolaryngology-Head and Neck Surgery, University of Washington, Seattle, Washington, 98195-7923; INSERM Unit 1051, Institute of Neuroscience, 34091, Montpellier, France.
Rémy
R
Pujol
Sarah B
SB
Pickett
Tot Bui
TB
Nguyen
Jennifer S
JS
Stone
D000429:Alcohol Oxidoreductases; D000818:Animals; D001306:Auditory Pathways / Q000166:cytology* / Q000378:metabolism; D002135:Calcium-Binding Proteins / Q000378:metabolism; D002452:Cell Count; D002685:Chiroptera; D002795:Choline O-Acetyltransferase / Q000378:metabolism; D056970:Co-Repressor Proteins; D004268:DNA-Binding Proteins / Q000378:metabolism; D018069:Hair Cells, Vestibular / Q000145:classification / Q000378:metabolism / Q000648:ultrastructure; D008322:Mammals / Q000033:anatomy & histology; D051379:Mice; D046529:Microscopy, Electron, Transmission; D009412:Nerve Fibers / Q000378:metabolism / Q000648:ultrastructure; D009415:Nerve Net / Q000378:metabolism / Q000648:ultrastructure; D009419:Nerve Tissue Proteins / Q000378:metabolism; D010750:Phosphoproteins / Q000378:metabolism; D051381:Rats; D055748:SOXB1 Transcription Factors / Q000378:metabolism; D013045:Species Specificity; D014722:Vestibule, Labyrinth / Q000166:cytology*
D002135:Calcium-Binding Proteins; D056970:Co-Repressor Proteins; D004268:DNA-Binding Proteins; D009419:Nerve Tissue Proteins; D010750:Phosphoproteins; D055748:SOXB1 Transcription Factors; D000429:Alcohol Oxidoreductases; C111341:Ctbp2 protein, mouse; D002795:Choline O-Acetyltransferase
000654; 000664; 737903; AB_10013626; AB_10015251; AB_10175616; AB_177520; AB_2068336; AB_2068506; AB_2079751; AB_2113875; AB_2282417; AB_2286684; AB_399431; AB_477329; JAX; RGD; mammal; morphology; synapse; type II hair cell; vestibular