my presentation

1. Regeneration of Nerve Fibre And
Its Criteria (Neuroregeneration)
Presesented By Muhammad Danish Zameer

2. Regenerationof
nervefibre
The term regeneration refers to
regrowth Of lost or destroyed part of a
tissue
 The injured and degenerate nerve
fibre can be regenerated
 Its starts as early as 4th day after
injury , but becomes more effective
only after 30 days and is completed in
about 80 days
 Only the PNS has ability of self-
regeneration but CNS is mostly
unable to do that

3. Criteriafor
Regeneration
 Regeneration is possible only if certain criteria
are fulfilled by the degenerated nerve fibre:
 Gap between the cut ends of the nerve should not
exceed 3mm
 Neurilemma should be present; as Neurilemma is
absent in CNS,the regeneration of nerve does not
occur in CNS
 Nucleus must be intact;if it is extruded from
nerve cell body,the nerve is atrophied and the
regeneration does not occur
 The two cut ends should remain in the same line-
regeneration does not occur if any one end is
moved away

4. Mechanism
Regenerationof
NerveFibre

5. Mechanismof
regenerationof
nervefibre
 When an axon is damaged,the distal segment undergoes wallerian
degeneration,losing its myelin sheath.The proximal segment can either die
by apoptosis or undergo the chromatolytic reaction, which is an attempt at
repair.
 Injury to PNS immediately elicits the migration of phagocytes ,schwann
cells and microphages to the lesion Site to clear away debris such as
damaged tissue.
 In case of severed nerve,the proximal end begins to sprout axons and the
presence of growth cones can be detected.Meanwhile,the distal end
experince wallerian degeneration within hours of the injury;the axons and
myelin degenerate but the endoneurium remains.
 The environment within the CNS, especially following trauma, counteracts
the repair of myelin and neurons .Glial scars rapidly form and the glia
actually produce factors that inhibits remyelination and axon repair.
 Human axon growth rates can reach 2mm/day
in small nerve and 5mm/day in large Nerves.
 Nerve regeneration is part of the pathogenesis
of many disease, including multiple sclerosis.