3.2 AGE-RELATED TISSUE CHANGES 3.2 AGE-RELATED TISSUE CHANGES

Central nervous system


In most organs ageing results in reduced cell division and replacement of active cells with connective tissue, however in the brain there is little connective tissue and postmitotic neuronal death results in a proliferation of active glial elements.

With advancing age the CNS may undergo morphological and chemical changes (see Table 3.1 and Table 3.2).

Peripheral nervous system


Morphological changes

Segmental demyelination and wallerian-type degeneration have been described to occur with advancing age in humans, but the changes are usually mild. Slowing of peripheral and central nerve conduction has also been demonstrated in elderly people.

Peripheral neuropathies may develop secondary to metabolic diseases such as diabetes mellitus. In the cat diabetic neuropathy is associated with distal axonal degeneration and affected animals show hind limb paresis with distal muscle atrophy and hyporeflexia.