Contractile cochlear frame in the gecko Teratoscincus scincus.
It is generally accepted that the cartilaginous frame of the reptilian cochlea has only a passive supportive function. In this study, a ribbon of contractile tissue was revealed within the cartilaginous frame of the cochlea of the gecko Teratoscincus scincus. It consisted of tightly packed cells and received an extensive blood supply. The cytoplasm of the cells was filled with cytoskeletal filaments 5-7 nm thick as revealed by electron microscopy. Isolated tissue permeabilized with Triton X-100 or glycerol reversibly contracted in the presence of ATP. Noradrenaline caused slow relaxation of the freshly isolated tissue placed in artificial perilymph. We suggest that slow motility of the contractile tissue may adjust passive cochlear mechanics to sounds of high intensities.
Institute of Evolutionary Physiology and Biochemistry, Academy of Sciences, St Petersburg 194223, Russia. o.ganeshina@mailbox.uq.edu.au
Olga
O
Ganeshina
Misha
M
Vorobyev
D000109:Acetylcholine / Q000502:physiology; D000222:Adaptation, Physiological; D000818:Animals; D001696:Biomechanical Phenomena; D002356:Cartilage / Q000033:anatomy & histology / Q000502:physiology; D003051:Cochlea / Q000033:anatomy & histology* / Q000502:physiology; D003285:Contractile Proteins / Q000502:physiology / Q000648:ultrastructure*; D006309:Hearing / Q000502:physiology; D008116:Lizards / Q000033:anatomy & histology*; D018377:Neurotransmitter Agents / Q000502:physiology; D009638:Norepinephrine / Q000502:physiology
D003285:Contractile Proteins; D018377:Neurotransmitter Agents; D000109:Acetylcholine; D009638:Norepinephrine