Embryology development of the limbs

(Bilaminar disc)

  • Epiblast
  • Hypoblast

Trilaminal germ disc

  • Mesoderm
  • Endoderm

Gastrulation

End of week 2

Day 15

Ectoderm

Mesoderm

Endoderm

Neural ectoderm

Notochord formation

Day 18

mesoderm origin cells


Induces ectoderm to form neural plate:

  • Neural tube: CNS
  • Neural crest: PNS

Surface ectoderm:

  • Epidermis
  • Outer layer of everything in the body

Inner layer of every part in the body

Paraxial mesoderm

Intermediate mesoderm

Lateral mesoderm

GU system

Somatic (parietal)

Splanchnic (viseral)

  • CVS
  • Mesothelial coverings of visceral organs
  • Appendicular skeleton
  • Most dermis
  • Lining of body wall

Somites (40)

Sclerotome

Dermomyotome

Somatogenesis

Diffrentiation

Anetriomedial

Posteriolateral

Myotome

Dermatome

Ventral subdivision

Dorsal subdivision

Vertebral body

Vertebral arch

around notochord -> Nuclues Polposus

Around neural tube -> Spinal Chord

Resegmentation

each sclerotome will be split into 2 halves (upper and lower) the lower half will grow and will fuse with the upper half of the sclerotome caudal to it (below it)
Will make muscle attachment to each sclerotome be for 2 vertebrae so gives VC more flexibility

  • 3 head (occipital)
  • 8 C
  • 12 T
  • 5 L
  • 5 S
  • 3 Co

Epimere

Hypomere

Give rise to skeletal muscles of the back

Give rise to skeletal muscles of the upper and lower limbs + ventral side of the trunck

will give rise to the dermis of the skin of the back


Dermis of the skin of ventral trunk and upper and lower limbs originates from the lateral mesoderm