The genesis of neurons and glia in the developing retina.

The retina is a highly complex neural organ that captures light and converts it into electrochemical signals that are transmitted to the brain to generate vision. There are five basic types of neurons that can be further divided into many specific subtypes, and one type of glial cell, all of which are generated during development from a common progenitor cell. The process by which this diversity of neurons is generated during development has been the subject of active investigation for over 40 years, and this review attempts to summarize the key concepts that have emerged. For example, many of the transcription factors that drive the progenitor to specific neuron types have been identified. Recent single cell genomic technologies have confirmed many of the discoveries in this field, but also highlighted gaps in our knowledge, e.g., the mechanisms of neuron subtype specification. In addition, several key issues in retinal neurogenesis are still unknown and require further study. We suggest that studying animals beyond the traditional model systems may shed light on some of the unresolved questions by highlighting mechanisms that allow species specializations in vision.