Brain development L4-6

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Understand the early embryonic events that result in the induction of neuroectoderm and formation of the neural tube

There ar many different neural tissues and cell types which result from patterning across anteroposterior (AP) and dorsoventral axes. Lumsen and Kinter liken this to a code based on Cartesian co-ordinates. Events are directed by local organisers which release diffusable morphogens, some are agonists and others are antagonists. We fos on vertebrate systems

Developmental processes are regulated by gradients of signalling factors, position, timing, competence and target tissues. Dorsoventral and Anteroposterior patterning work in combination in key neural development.

Manny different neural tissues result from patterning from the AP and DV axes. Neural developmental events are directed by local organisers that release diffusible morphogens with some agonistic and antagonistic processes.

In early embryogenesis there are 3 germ cell layers, the ectoderm, endoderm and mesoderm. The ectoderm portion called the epiblast develops into the neural plate during gastrulation. It is a precursor for the central and peripheral nervous system. When the dorsal neural folds close they form the neural tube. The neural tube is over the notochord and is flanked b somites. Oviod groups of mesodermal cells give rise to muscle and cartilage . At blastula stages growth factors such as FGF, Wnts and nodal related families induce mesodermal derivatives

The neural plate forms a tube consisting of Neuroepithelial cells (NECs) arranged around a central lumen that extends along the Anterior-posterior axis. In addition to the neural plate, the ectoderm also forms the neural crest. The neural crest is a population of migrating precursors that move throughout the embryo generating neural and non neural cell terms. Furthermore ectodermal cells produce placodal structures containing neural precursors for sensors ganglia and neutrons in the ear and nose. Other ectoderm regions produce the skin. The neural precursors arise in vertebrate embryos during gastrulae stages when the ectoderm is subdivided into regions with different developmental fates. This process occurs due to the interaction of the ectoderm and organiser. At gastrulae stages the ectoderm on the ventral side forms the epidermis due to BMP signalling whereas other regions avoid BMP signalling through organiser inhibition producing neural tissues. Neural tissues respond to a variety of patterning signals that divide into different neural fates

1930 experiment showed the organiser within the doral blastopore lip. They explanted the tissue into a different embryo and noted that 2 neural tubes were formed giving evidence of the organiser centre being responsible for neural tissues. The organiser actually turned out to release BMP antagonists. BMP inhibition allows for the production of neural tissue.

https://www.sciencedirect.com/science/article/pii/B9780124366435500274

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Be able to describe how extra-cellular signalling molecules can pattern the presumptive spinal cord and specify neuronal identity.