Ultrastructure of sciatic nerve of armadillo infected with Mycobacterium leprae.

Ultrastructural observation of sciatic nerves from eight Armadillos were made. Six animals had intravenous inoculation of M. leprae, one had of foot pad, while one had natural leprosy. The available nerves were biopsied at various time sequence ranging from five weeks to twenty four months. Semithin sections did not reveal any neuropathy. Ultrastructurally perineurium was thick and endoneurial collagen was increased. Initially demyelination of non-myelinated fibres was seen in all nerves irrespective of mode of infection. This was followed by demyelination of small myelinated fibres. Active remyelination was predominantly after 17 months. Schwann cell activity was increased and various stages of division were seen. Bacilli were extracellular, intraxonal, in endothelium and in perineurium. Significant observations were on blood vessels. These observations are discussed.