C21 CNS

Question 1

reactions of neurons to injury

Answer 1

Neuronal injury may be an acute process, often a consequence
of depletion of oxygen or glucose or trauma, or a
slower process, often associated with accumulation of
abnormal protein aggregates, as occurs in degenerative
disorders of the brain.

Question 2

Define red neurons

Answer 2

Acute neuronal injury (“red neurons”) refers to a spectrum of changes that accompany acute CNS hypoxia/ischemia or other acute insults and reflect the earliest morphologic markers of neuronal cell death (see Fig. 28-13B). “Red neurons” are evident by about 12 to 24 hours after an irreversible hypoxic/ ischemic insult. The morphologic features consist of shrinkage of the cell body, pyknosis of the nucleus, disappearance of the nucleolus, and loss of Nissl substance, with intense eosinophilia of the cytoplasm.

Question 3

Define axonal reaction

Answer 3

Axonal reaction is a change observed in the cell body during regeneration of the axon; it is best seen in anterior horn cells of the spinal cord when motor axons are cut or seriously damaged. There is increased protein synthesis associated with axonal sprouting. This is reflected in enlargement and rounding up of the cell body, peripheral displacement of the nucleus, enlargement of the nucleolus, and dispersion of Nissl substance from the center to the periphery of the cell (central chromatolysis).