EMBRYOLOGY(1st year)

1. DEVELOPMENT OF CNS

4. • The wall of neural tube at 1st has single layer
of cells. The cells multiply & form 3 layers:
1)Ependymal 2)Mantle 3)Marginal.
• Mantle layer divides into ventral part- the
basal lamina & dorsal part- the alar lamina.
These are separated by sulcus limitans.

6. DEVELOMENT OF MEDULLA OBLONGATA

7. DEVELOMENT OF MEDULLA OBLONGATA
• Develops from myelencephalon.
• Early development similar to spinal cord.
Appearance of sulcus limitans divide lateral wall
into- Alar lamina & Basal lamina
Widening of thin roof plate
As a result, alar lamina comes to lie dorso
lateral to basal lamina
Both lamina are now in floor of developing
4th ventricle.

8. DEVELOMENT OF MEDULLA OBLONGATA
• Cells developing in lateral part of each alar lamina
migrate ventrally & reach marginal layer overlying
ventrolateral aspect of basal lamina.
• These cells constitute caudal part of BULBO
PONTINE EXTENSION & develop into olivary
nuclei.
• The remaining cells of alar lamina develop into
sensory nuclei of CNN.
• The motor nuclei of these nerves derived from
basal lamina.

9. DEVELOPMENT OF PONS

10. DEVELOPMENT OF PONS
• Arise from:-
Ventral part of metencephalon
&
Cranial part of bulbopontine extension
(Alar lamina of myelencephalon).
--- Cranial part of bulbopontine extension give rise to Pontine
nuclei.
---ALAR LAMINA: Lateral part becomes RHOMBIC Lip
(cerebellar rudiments) &
Ventral part gives origin to sensory CNN.
---BASAL LAMINA: gives motor CNN

11. DEVELOPMENT OF CEREBELLUM

12. DEVELOPMENT OF CEREBELLUM
• Develops from dorsolateral part of alar lamina
of metencephalon(cerebellar rudiments as
rhombic lip).
• Some cells of mantle layer of cerebellum
migrate into marginal layer to form cerebellar
cortex.
• The cells of mantle layer that do not migrate
into cortex develop into- dentate, emboliform,
globose & fastigal nuclei.

13. • SUPERIOR cerebellar peduncle- formed by
axons growing out of dentate nucleus.
• MIDDLE cerebellar peduncle- formed by axons
growing into cerebellum from cells of pontine
nuclei.
• INFERIOR cerebellar peduncle- formed by
fibres that grow into cerebellum from spinal
cord & medulla.

15. DEVELOPMENT OF MIDBRAIN
• Alar lamina of mesencephalon forms colliculi,
red nucleus & substantia nigra.
• Basal lamina: oculomotor nucleus, trochlear
nerve nucleus, edinger westphal nucleus.