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Neurologic signs are explained by lesions in the central nervous system, which are most specific and diagnostic for the disease. These consist of bilatterally symmetrical focal malacia of the basal ganglia, substantia nigra and thalamus and bilaterally symmetrical demyelination in the internal capsule, subcortical white matter and cerebellar peduncles. The harmful effect of the toxin on endothelium is particularly obvious in the brain. Damaged endothelial cells develop pyknotic nucelei and the vessels become surrounded by oedema. Ultrastructurally, the perivascular astrocyte end-feet are markedly swollen.
Neurologic signs are explained by lesions in the central nervous system, which are most specific and diagnostic for the disease. These consist of bilatterally symmetrical focal malacia of the basal ganglia, substantia nigra and thalamus and bilaterally symmetrical demyelination in the internal capsule, subcortical white matter and cerebellar peduncles. The harmful effect of the toxin on endothelium is particularly obvious in the brain. Damaged endothelial cells develop pyknotic nucelei and the vessels become surrounded by oedema. Ultrastructurally, the perivascular astrocyte end-feet are markedly swollen.
The ultrastructural changes on experimental disease consist of periaxonal and intramyelinic oedema in cerebellar white matter and swelling of axon terminals and dendrites in grey matter adjacent to lateral ventricles. Swelling of mitochondria is also an early feature. Occlusion of capillaries by aggregated platelets, accompanied by petechiae in relation to the malacia, suggests that changes in vascular endothelium may be the primary effect of the toxin. This concept is supported by eveidence that the capillaries in affected parts of the brain leak consipcuously within 90 minutes after administration of ''C. perfringens'' type D toxin.
[[Image:pulpy kidney disease.jpg|thumb|right|150px|Pulpy kidney disease- histological (Courtesy of Bristol BioMed Image Archive)]]
[[Image:pulpy kidney disease.jpg|thumb|right|150px|Pulpy kidney disease- histological (Courtesy of Bristol BioMed Image Archive)]]