wallerian Degenration

1. WALLERIAN DEGENERATION
when a nerve fiber is cut or crushed and thIt is
an active process of degeneration that results e
part of the axon distal to the injury (i.e. farther
from the neuron's cell body) degenerates.
process that occurs when a neuron is damaged
so severely that part of the axon is disconnected
from the soma of the neuron. The disconnected
portion of the axon is degenerated .

2. Occurrence:
A related process of dying back or retrograde degeneration known
as 'Wallerian-like degeneration' occurs in many neurodegenerative
diseases, especially those where axonal transport is impaired such
as ALS and Alzheimer's disease. Primary culture studies suggest
that a failure to deliver sufficient quantities of the essential axonal
protein NMNAT2 is a key initiating event.
Symptoms:
 Muscle weakness Limb numbness Altered sensation.

3. STAGES OF WALLERIAN
DEGENERATION
 The first stage occurs during the first 12 hr after
axotomy at 37°C and is prolonged by low
temperatures.
 Events during the first stage appear to initiate the
process leading to Wallerian degeneration.
 The second stage occurs during the period 12–24
hr after axotomy at 37°C.

5. ZENKER'S DEGENERATION
 Zenker's degeneration is a severe glassy
or waxy hyaline degeneration or necrosis of
skeletal muscles in acute infectious diseases.
 Death of segments of muscle cells that sometime
occurs in prolonged fevers such as TYPHOID or in
HEPATITIS. Also known as hyaline necrosis. (Friedri
ch Albert von Zenker, German pathologist, 1825–89).

6. SYMPTOMS:
Dysphagia (difficulty swallowing)
Regurgitation (return of undigested food back into the
mouth)
Sense of a lump in the neck.
Halitosis (smelly breath) due to stagnant food in the pouch.
Cough, especially at night.
Hoarseness (voice change)
Involuntary gurgling noises when swallowing.

7. Diagnosis
Zenker's diverticulum is diagnosed using a test called a
barium swallow. A barium swallow is a special X-ray that
highlights the inside of your mouth, pharynx, and
esophagus. A barium swallow fluoroscopy allows your
doctor to see how you swallow in motion.
Treatment:
Treatment options encompass open surgery or transoral
rigid or flexible endoscopy and are aimed at eliminating
functional out flow obstruction .

9. PYKNOSIS, OR KARYOPYKNOSIS,
(from Greek pyknono meaning "to thicken up, to
close or to condense") is also observed in the maturation
of erythrocytes (a red blood cell) and the neutrophil (a
type of white blood cell).
irreversible degeneration of a cell in which the nucleus
shrinks in size and the chromatin condenses to a solid,
structureless mass or masses.

10. OCCURRENCE:
Pyknosis occurs in senescent (old) leukocytes and
results from preprogrammed cell death (apoptosis).
With pyknosis, the nucleus becomes dense and
compact and begins to fragment (karyorrhexis)
resulting in spheres of dark-staining nuclear chromatin.

11. KARYORRHEXIS
 Karyorrhexis (from Greek κάρυον karyon, "kernel,
seed or nucleus", and ῥῆξις rhexis, "bursting") is the
destructive fragmentation of the nucleus of a dying
cell whereby its chromatin is distributed irregularly
throughout the cytoplasm.
Causes:
MPT is caused by many mechanisms, including
oxidative stress, and some xenobiotics,increase PT pore
opening by a calcium-dependent mechanism.