The Senses

Bernd Fritzsch; Karen L. Elliott

doi:10.1201/9781003092810-1

The dorsal spinal cord and brain receive sensory input from peripheral sensory neurons and sensory receptor cells. In chordates, the brain and spinal cord develop from the dorsal ectoderm that eventually forms the neural tube, whereas the various sensory neurons and receptor cells develop from distinct placodes and neural crest cells for the vertebrate species that have them. Antero-posterior patterning of the hindbrain and spinal cord is driven largely by Hox genes, along with other genes. In addition, there is a shared general dorso-ventral sequence of gene expression, Atoh1, Neurog1/2, Ascl1, and Ptf1a, among others, to regulate and pattern the dorsal aspects of the hindbrain and spinal cord. The development of sensory neurons and receptor cells is primarily driven by early expression of Eya1/Six1, followed by Sox2. Later expression of bHLH genes in placode and neural crest cells further differentiate sensory neurons, specifically Neurog1/2 (most sensory neurons) and Atoh7 (retinal ganglion neurons). Mechanosensory cells, such as hair cells, critically depend on Atoh1, whereas the sensory cells in the visual system, the rods and cones, depend on Neurod1. Moreover, taste receptors depend on Sox2 and Neurog2. Olfactory receptors are unique as they are located on olfactory neurons that have a direct input into the olfactory bulb. This chapter will provide a brief overview of brain and spinal cord development along with the development of sensory neurons and receptor cells in each of the sensory systems.

The Senses

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