Development Of The Nervous System Flashcards
What is neurulation?
The process of how the ectoderm begins to give rise to the nervous system (even though the PNS is formed separately from the CNS)
What are the three key events during neurulation?
Contact between notochord and future floor place - contact specifies the overlying ectoderm to become the NS
Folding, delamination of neural crest
Closure, crest migration, roof plate formed, notochord separates
Are motor neurones found in the ventral or dorsal horn?
Ventrally - more prominent swelling in areas where limbs are present / to control contraction or many more limb muscles that are there as suppose to chest
What are the four stages that pluripotent ectodermal cells have to pass to become neural precursor cells or progenitor cells and then neurones
Become progenitors
Specification (stay or leave from progenitor characteristics)
Enter neural differentiation pathway
Exit cell cycle and express neuronal genes
What are progenitor cells?
Stem cells located close to the midline
What are morphogens?
Proteins present in the developing embryo that give positional information to cells via a concentration gradient and alter cell fates
What is induction?
Instructing the development of cells through the local communication among embryonic cells
What are organising centres?
Groups of inducing cells during development that secrete signals (not necessarily instructive)
What are morphogens critical for?
The generation of distinct neural subtypes at distinct positions in the dorso-ventral axis of the neural tube
What gives rise to the floor plate?
The notochord
What induces ectopic motor neurones?
The floor plate
What is Shh?
Sonic hedgehog is a signalling molecules made in the notochord and floor plate
What did early in vitro experiments show that Shh does?
Changes the fate of neural plate explanation in a concentration-dependent matter
acting as a morphogen, higher conc (10nM) Shh generates floor plate and lower (1nM) conc Shh generates motor neurones
