BIOM3002 Lecture Notes - Lecture 2: Paraxial Mesoderm, Lateral Plate Mesoderm, Notochord
26 May 2018
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EMBRYOLOGY LECTURE TWO
WEEK 4: NEURAL TISSUE INDUCTION AND MORPHOGENESIS
Major event embryo: beginnings of NS (basically whole embryo)
Over next 2-3 weeks: other organs start developing
Diagram: Amniotic cavity; ectoderm; notocord [mesoderm]; yolk
sac
Notocord function: induces overlying ectoderm to turn into
neural tissue
-> goes on to give rise to portion of nucleus pulposus of IVD
Neural fold
Neural crest
Neural groove
Intermediate zone neural crest
Columnar and fatter at base thus groove –> tube -> CNS
Notocord: Dorsal Root Ganglion [DRG] of Peripheral Nervous
System [PNS] in segments down spinal cord – bipolar neurons
send axons peripherally, and sends another axon back into
neural tube
If you don't zip at one end neural tube: pore-facing the
environment [anencephaly; major portion brain/skull/scalp
absent]
Upon survival @ rear end = tuft of hair at base spinal cord
Week 4 – SOMITOGENESIS: migrating mesoderm [laterally]
1. Paraxial mesoderm beside notocord
2. Intermediate mesoderm – kidneys
3. Lateral plate mesoderm
Paraxial mesoderm: next to notocord, balls of mesoderm
(somites) aggregate [2x somites per segment]
• Each gives rise to muscle and deep skin [dermis]
• Each innervated by peripheral nerve exiting neural tube
• Form cranially - caudally
Heart and BVs: late WEEK 3 [vasculogenesis]
Notocord
Columnar epithelium enlarging above neural plate
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