[A] 1.45 Regeneration of muscle and neural tissue

Question 1

Complete regeneration of muscle tissue

Answer 1

Cross-striated skeletal muscle - After segmental necrosis

1. Sarcolemma & satellite cells of myocytes are intact
2. Satellite cells proliferate to form myoblasts
3. Myoblasts form myotubes
4. Scar formation (always in smooth & heart muscle)

Question 2

Regeneration of muscle tissue: Complete necrosis

Answer 2

Heart & smooth muscle

• Scar formation

Question 3

Striated muscle regeneration: With sarcolemma destroyed

Answer 3

• Only muscle bud production
• The connection is not restored
• Muscle function may be intact

Seen in: Muscle rupture, contusion, complete necrosis

Question 4

Regeneration of neural tissue: Overview

Answer 4

No regeneration in the CNS

• Nerve cells: Highly differentiated cells
• Nerve fibres: No regeneration ability
  
  • Glial scar formation at the site of injury
• More regeneration in the PNS
  
  • Even after transection!

Question 5

Steps of neural tissue repair

Answer 5

1. Centripetal/proximal end survives
2. Wallerian degeneration
3. Centrifugal/distal end necrotises
4. Resorption & remotion
5. Büngner’s bands from the Schwann cells
6. Axonal regeneration
7. Synaptic & neuromuscular junctional regeneration

Question 6

Neural tissue regeneration: Difficulties

Answer 6

• When stumps are too far from eachother
  
  • Only connective tissue connects at the ends
  • Schwann cells are destroyed
    
    • No regeneration
  • Schwann cells of the central still proliferate
  • Onion bulbs