Genetic and Tissue Interactions in the Embryogenesis of the Diencephalon and Circumventricular Organs

Abstract

The posterior forebrain (diencephalon) is one of the vesicles that emerges in the anterior neural tube early in embryogenesis. It gives rise to the thalamus (the major relay station of the brain), the prethalamus and pretectum, the epithalamus including the habenular complex, the hypothalamus including the posterior lobe of the pituitary gland and the retinas of the eyes. It also generates a number of circumventricular organs, highly specialised sensory and secretory structures that lack a blood‐brain barrier and that allow for the exchange of substances between the brain and the circulatory system. I will give an overview of the genetic mechanisms that regulate the embryonic development of the diencephalon with a focus on (a) the role of secreted signals and transcription factors and (b) interactions between tissues. The pituitary gland proper develops through an interaction between neural (hypothalamus‐derived) and non‐neural (placode‐derived) tissues, and our recent work indicates that the pineal organ forms through a similar interaction between neural and placodal tissues, suggesting a common theme in the establishment of diencephalon‐derived neurosecretory and sensory structures.Support or Funding InformationThis work has been supported by King’s College London.