Ear and Lateral Line of Vertebrates: Organisation and Development

Abstract

In vertebrates, perception of movement and sound is accomplished by the lateral line and inner ear sensory systems. These systems sense reverberations, movement and acceleration by transducing mechanical stimuli from the environment into electrical signals by means of mechanosensory hair cells. Vestibular and auditory hair cells have associated sensory neurons that transmit these signals from the periphery to the central nervous system. During development, cranial sensory systems arise from an initially homogeneous population of cells that ultimately give rise to discrete sensory structures. Although the demands for auditory and vestibular sensation differ between species and environments, vertebrates use common cell types, genetic programmes and molecules to achieve the development of these mechanosensory organs. In this article, the structure and function of the mechanosensory hair cells, lateral line and inner ear and how these systems develop across species are discussed, and as well as the innervation of these systems. Key Concepts: The vertebrate inner ear is composed of both auditory and vestibular components. Both the lateral line and the inner ear are derived from embryonic structures known as cranial placodes. All cranial placodes originate from a homogenous group of cells known as the preplacodal ectoderm. Hair cells are structurally and functionally similar in both auditory and lateral line systems. The adult lateral line mediates sensation of movement in the aquatic environment of fishes and frogs. Embryonic posterior lateral line development is accomplished by the pre‐patterned posterior lateral line primordium. The lateral line is an experimentally accessible model for studying mechanosensory system development and biology.