Brain, Neuron - Degeneration

Olfactory bulb neuronal degeneration in a female B6C3F1 mouse from a chronic study. The arrow indicates the vacuolation and neuronal degeneration of the olfactory bulb. Gl, glomerular layer; EPl, external plexiform layer; GrO, internal granule cell layer.
Figure 1 of 5

Higher magnification of the internal granule cell layer in the normal olfactory bulb in a female B6C3F1 mouse from a chronic study.
Figure 2 of 5

Granulovacuolar neuronal degeneration in a male F344/N rat from an acute study. The black arrowhead indicates neuronal granulovacuolar change, the black arrows identify neurons with central chromatolysis, and the white arrow identifies a genuine basophilic necrotic neuron.
Figure 4 of 5

Granulovacuolar neuronal degeneration in a male F344/N rat from an acute study. Higher magnification of Figure 4. The black arrow indicates neuronal granulovacuolar change, the arrowhead identifies a neuron with central chromatolysis, and the white arrow identifies a genuine basophilic necrotic neuron.
Figure 5 of 5
comment:
It is important for the pathologist to be aware of the various forms of subtle early changes associated with neuronal injury. These types of neuronal changes may be evident in animals receiving lower doses of the test compound, or in nuclei of the brain less vulnerable to the agent from higher dosed animals. Injury to neural tissue may involve one or more modes, such as vascular injury in which fluid accumulates in the neuropil, creating a vacuolated appearance of the region. Direct neuronal injury may involve the membrane and ion and fluid transfer, in which case vacuoles may become evident in the neuronal perikaryon. Commonly, the injury involves metabolic processes, particularly disturbances to neuronal energy production, in which case cell death occurs characterized by central chromatolysis, neuronal necrosis, and ultimately lysis. Figure 1





Figure 4


recommendation:
When present, neuron degeneration should be diagnosed, the subsite noted, and the severity graded. In the presence of concurrent lesions, lesions with the most severity are typically diagnosed. Other concurrent lesions may be diagnosed separately, if warranted by the severity.references:
Cavanagh JB, Holton JL, Nolan CC, Ray DE, Naik JT, Mantle PG. 1998. The effects of the tremorgenic mycotoxin penitrem A on the rat cerebellum. Vet Pathol 35:53-63. Abstract: http://www.ncbi.nlm.nih.gov/pubmed/9545135
Colman JR, Nowocin KJ, Switzer RC, Trusk TC, Ramsdell JS. 2005. Mapping and reconstruction of domoic acid-induced neurodegeneration in the mouse brain. Neurotoxicol Teratol 27:753-767. Abstract: http://www.ncbi.nlm.nih.gov/pubmed/16109471
Web page last updated on: January 02, 2014