Embryology Formation Of Germ Short Essay Question And Answers

Question 1. Somites
Answer:

• Cells of paraxial mesoderm gets segmented into somitomeres and somites
• Somites are cubical and more distinctly segmented
• Most cranial somites are located in occipital region New somites are formed caudal to them
• There are about 44 pairs of somites
  • 4-occipital
  • 8-cervical
  • 12-thoracic
  • 5-lumbar
  • 5-sacral
  • 8-10-coccygeal

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Somites Fate of Somites:

• Ventromedial part called sclerotome gives rise to the vertebral column and ribs
• Lateral part called dermatome give rise to the dermis of the skin and to subcutaneous tissue
• Intermediate part called myotome gives rise to striated muscle
  Cranial to it:
  • Occipital somites give rise to muscles of the tongue and supplied by hypoglossal nerve
  • Pre-occipital somites are supplied by third, fourth and sixth cranial nerves

Question 2. Morula
Answer:

• A process called cleavage occurs which divides the ovum into smaller cells
• When ovum comes to have 16 cells it looks like mulberry so called morula

Morula Layers:

1. Inner cell mass
   • Gives rise to embryo proper
2. Outer layer of trophoblast
   • Completely surrounds the inner cell mass
   • Helps to provide nutrition to embryo
3. Fluid from uterine cavity separates the inner cell mass and cells of trophoblast