Cochran SL.

ASGSB Bull. 1995 Oct; 9: 34.

Depts. Otolaryngology and Anatomy and Neuroscience, Univ. Texas Medical Branch, Galveston, USA.

The purpose of this study is to understand how the synapses in the inner ear of the turtle (which possesses both type I and type II hair cells) contribute to the ability to sense gravity and motion. Anesthetized turtles were decapitated and the inner ears were removed and then processed for electronmicroscopy. Four types of synapses are found in the neuropils of the canals and utricle. Type II hair cells form connections with vestibular afferents that consist of spherical dense bodies surrounded by a halo of synaptic vesicles with a dense postsynaptic thickening. Vesicular profiles are located in the afferent cytoplasm, but they are not clustered at the plasma membrane suggesting no reciprocal synaptic contact. Type I hair cells form similar contacts with the afferent calyces. Efferent boutons contact type II hair cells and there is an associated subsynaptic cistern. Efferent boutons also contact the afferents, but instead of forming a subsynaptic cistern, there is a postsynaptic thickening of the afferent membrane. In some cases the same bouton can be seen contacting a hair cell and an afferent, forming a subsynaptic cistern with the hair cell and a postsynaptic thickening with the afferent, suggesting that the same population of efferents can innervate both hair cells and afferents. These findings also suggest that the transmitter involved in efferent to hair cell and efferent to afferent transmission is the same. These results are preliminary to understanding how the transduced hair cell signal is communicated to the afferents and how the efferents may be able to modify this communication.

Publication Types:

• Meeting Abstracts

Keywords:

• Hair Cells, Auditory
• Saccule and Utricle
• Semicircular Canals
• Synapses
• Synaptic Vesicles
• ultrastructure
• NASA Discipline Neuroscience
• NASA Discipline Number 40-10
• NASA Program Space Biology
• Non-NASA Center

Other ID:

• 97615607

UI: 102222753

From Meeting Abstracts