Diencephalon Development

The Epithalamus, Thalamus, and Hypothalamus

The term diencephalon means the “between brain.”  The two main components of the diencephalon are the thalamus and the hypothalamus.  This part of the brain links the phylogenetically older brainstem to various structures in the phylogenetically newer telencephalon.  Embryologically, the diencephalon is considered to be part of the forebrain along with the telencephalon.  We have studied all aspects of diencephalic development at the cell and tissue level by determining neurogenetic timetables in all of the adult structures in the diencephalon with long-survival 3H-thymidine autoradiography.  Using short-survival 3H-thymidine autoradiography we determined the location of source areas in the diencephalic neuroepithelium for specific nuclei.  Finally, using sequential-survival 3H-thymidine autoradiography, we followed the migratory pathways of diencephalic neurons to their settling sites in specific regions of the brain parenchyma.

Our main finding is that the diencephalic neuroepithelium is a mosaic with specific locations giving rise to specific nuclei in a spatiotemporal production sequence of neurons, migratory pathways, and settling patterns in mature nuclei.  We have published 15 papers in peer-reviewed journals from 1969 through 1990, and a monograph on hypothalamic development that appeared in  1986 (Altman&Bayer, Advances in Anatomy, Embryology, and Cell Biology, volume 100).

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