A semi quantitative analysis of bacterial load in different cell types in leprous nerves using transmission electron microscope.

Thirty lepromatous (BL-LL) and 25 tuberculoid (TT-BT) nerve lesions obtained from untreated cases of leprosy were scanned using transmission electron microscope for assessing the bacterial load in different cell types. Major bulk of infection was seen in the Schwann cells of nonmyelinated fibres, in both early lepromatous and tuberculoid nerve lesions, suggesting that M. leprae spread mainly via the Schwann cells within the nerve.

Reaction of peripheral nerves to vascular and bacterial injuries.

Mouse sciatic nerves were subjected to devascularization, M. leprae inoculation, and combined insult of devascularization + footpad inoculation (FPI). Changes were seen in FPI nerves only after eight months, but in cases of combined insult, changes were evident in hours. Both the groups showed initial loss of small myelinated fibres. No proliferation of Schwann cells was in FPI nerves, but in combined insult it was maximum after two weeks. Presence of M. leprae seems to be arresting Schwann cell activity after two weeks. Blood vessels showed increased endothelial cell cytoplasm, basement membrane proliferation and villi formation. These changes seem to be specific of endoneurial blood vessels of leprosy nerves. Increased number of mast cells seems to be specific of devascularized and FPI nerves. Increased number of macrophages expressed low immunity of devascularized nerves. Eosinophils migrated to endoneurium as a result of leakage of axoplasm.