Paraaxial, intermediate, lateral plate mesoderm

The intraembryonic mesoderm differentiates into:

  1. Paraaxial mesoderm
  2. Intermediate mesoderm
  3. Lateral plate mesoderm

 

Image result for intraembryonic mesoderm

 

Paraaxial mesoderm

Transverse grooves appear dividing it into somites, from cranial to caudal end.

42 to 44 somites form;

  • 4 occipital
  • 8 cervical
  • 12 thoracic
  • 5 lumbar
  • 5 sacral
  • 8 – 10 coccygeal

Image result for somites

 

The somites then differentiate in a cranio-caudal direction into:

Image result for differentiation of somites

  1. Sclerotome – forms connective tissue, cartilage cells and bone cells of axial skeleton 
  2. Myotomes – differentiate into myoblasts, which then forms skeletal muscles of the body
  3. Dermatome – forms dermis of skin

 

Intermediate mesoderm

  • Cervical – segmented
  • Thoracic – partially segmented
  • Lumbar – unsegmented. forms nephrogenic cord (source of urinary system)

Origin to:

  • Cortex of suprarenal gland
  • Nephrons
  • Gonads

 

Lateral plate mesoderm

Image result for lateral plate mesoderm

Due to formation of intraembryonic coelom, it is divided into:

1. Somatic layer:

  • Adherent to ectoderm
  • Forms muscles and connective tissue of body wall

2. Splanchnic layer:

  • Adherent to endoderm
  • Forms serous membranes: Pleura, Pericardium, Peritoneum
  • Smooth muscles
  • Connective tissue of GIT, respiratory tracts
  • Cardiovascular system

The intraembryonic coelom forms:

  • Pericardial cavity
  • Peritoneal cavity
  • Pleural cavity

 

Other derivatives of the mesoderm:

  • All skeletal, smooth and cardiac muscles
  • Bone marrow and blood cells
  • Spleen
  • Lymph nodes
  • Dura matter
Advertisements

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

w

Connecting to %s