Neural Development Flashcards
What tissue layer develops into neural components?
ectoderm
What organ system is developed first?
-Nervous system is the first organ system to be created (although it is not the first system to be functional)
Neurulation
-the process of ectoderm folding to become the central nervous system
Neural Crest vs. Neural Tube
-Neural crest: becomes PNS
-Neural tube: becomes CNS
Neuroectoderm development
-neural tissue develops from a small portion of ectoderm
-Notochord (central mesoderm) signals with Sonic the Hedgehog to ectoderm resulting in differentiation to become neuroectoderm
Neural crest development
-several layers of ectoderm migrate laterally to form neural crest which will become PNS
Neural Tube formation
-neural fold fuses at the midline (both dorsally and transversely), giving rise to the neural tube
-the neural tube then fuses and extends in a cranial and caudal fashion
-Neural tube becomes CNS
Somites
-lateral collection of specialized mesoderm (paraxial mesoderm)
- forms bones, muscles, and connective tissue of the vertebral column and the rib cage
Nutrients and vitamins for proper embryogenesis
-many are critical but folic acid (Vitamin B9) seems to be very important in preventing neural tube defects
**Failure of neural tube closure results in developmental abnormalities
Can viruses cause neural tube defects
yes
Common neural tube defects
-Anencephaly (no cranial closure of neural tube)
-Spinal bifida (incomplete closure of neural tube anywhere; lacking proper somites development/protection)
-Dermoid sinus (incomplete separation between skin and nervous system so no protection)
-tethered cord syndrome (incomplete separation from the nervous and connective tissue; additional ligaments that cause pulling and pain within)
Manx Cats and Neural tube closure failure
-Caudal neural tube defect (incomplete closure)
-Can result in no tail/vertebrae, no caudal spinal cord, pelvic limb dysfunction (mild/moderate/severe), death
Stumpies=short tail; Rumpies=no tail
Rumpies breeding
-if you breed 2 together, usually have offspring that have hind limb defect
**Note: need up to Saccral 3 to control bowels
Rhodesian Ridgebacks and neural tube failures
-incomplete closure of neural tube (dorsally) results in dermoid sinus formation
-ectoderm (skin) is incompletely separated from the neuroectoderm (spinal cord) and this causes abnormal hair growth (often longer, grows in opposite direction, or darker pigmented hairs)
-various depths of dermal sinuses (penetrations) are observed
Processes for developing CNS after neural tube formed and closed
1.cell division
2.cell migration and differentiation
3.axonal outgrowth and pathfinding
4.synapse formation and remodeling
5. myelination