Neurulation

Question 1

Neurulation stages

Answer 1

▪️thickened neural plate
▪️shaping of plate to become narrower and longer
▪️lateral folding of the neural plate into neural folds
▪️fusion of the two most apical surfaces into neural tube

Question 2

Week 3-4 (neurulation)

Answer 2

▪️cells in ectoderm thicken to form N plate due to NC
▪️neural plate invaginates to form N grove
▪️lateral edges of neural plate becomes elevated to form N folds
▪️cells detach from top of N folds to form N crest cells (melanocytes, connective tissue, head and neck muscles)
▪️N folds begin to move towards each other and fuse creating N tube
▪️N tube separates from ectoderm surface which fuses together

Question 3

Full closure of neural tube

Answer 3

▪️until fusion is complete, caudal and cranial ends are open to communicate with amniotic cavity (anterior and posterior neuropores)
▪️cranial neuropore closes day 25
▪️caudal neuropore closes day 28

Question 4

Neural tube abnormalities

Answer 4

▪️anencephaly 
-fails to close in cranial region 
-brain fails to form 
▪️spina bifida 
-fails to close anywhere
-usually lumbarsacral region 
-70% prevented by folic acid in pregnancy