The document discusses neurulation, the process of formation and closure of the neural tube. It involves primary and secondary neurulation, which are guided by molecular signaling pathways involving molecules like Shh, BMP4/7, and cadherins. Defects in neurulation can result in neural tube defects like anencephaly or spina bifida. While neurulation was once thought to be a simple one-step process, it is now understood to be more complex, with closure occurring in regions rather than entirely linearly.

1. Neurulation and
Neural Crest Cells
Neha Kaundal (10050)
Sandeep Satapathy(10079)
Smrithi Krishnan R(10090)

2. NEURULATION
PRIMARY
SECONDARY

3. How Secondary Neurulation?????

4. SPEMANN ORGANIZER
CHANGE THE FATE OF CELL…!!!!
INDUCES NEURAL PLATE FORMATION
HOW…..??
SECRETE MOLECULES
FOLLOW DEFAULT
PATHWAY
NEURAL FATE

5. Molecular Signaling of
Primary Neurulation
Positional confirmation for
spatial differentiation

6. NEURULATION
BEGINS
HERE...!!!
Shh Signaling from the
Notochord reaches the
MHP of the
neuroepithelium

7. BMP4/BMP7
Neural Boundary
Cells
MHP
Somites
Chondrin, noggin,
Follistatin
FGF
|---------------------|
Fated
Neural
Crest Cells
Neural Crest
Cells
E-cadherin
N-cadherin
N-CAM
Hyaluron

9. Zippering action -Closure of Neural
Tube
Completes in
25days post
embryonic
development
Completes in 27
days post
embryonic
development
Apical constriction by
rearrangement of
actin, tubulin effect of
BMP4/7 signaling
Basal bulging out caused by
movement of nucleus into this
space signaled by shh from
notochord

10. Cell Fates-Neural tube cells/Neural
crest cells

11. SENSORY NEURONS
MOTOR NEURONS
FORMATION OF
HEAD,TRUNK &TAIL

12. 24-hr Chick
22-23 days of Human

13. DEFECTS……..
ANENCEPHALY SPINA BIFIDA
END OF NEURROSTRAL
AL TUBE FAILS TO
CLOSE
MISEPRESSION OF WRONG CADHERIN
LEADS TO FAIL TO SEPARATE
EPIDERMAL ECTODERM AND NEURAL
LAYER

14. EXPERIMENTAL APPROACHES

15. Unfortunately, simplicity is not the answer.
In actuality, the folding of the neural tube is still not entirely
understood.
The simplistic model of the closure occurring in one step
cranially and caudally does not explain the high frequency of
neural tube defects.
Proposed theories include that closure of the neural tube occurs
in regions, rather than entirely linearly

16. Thank You