Ultrastructural alterations of mycobacterium leprae in skin biopsies of untreated and treated lepromatous patients.

1. -- Mycobacterium leprae cells under a process of progressive disaggregation are present in the skin of both treated and untreated patients. 2. -- The ultrastructural alterations observed during the degenerative process seem to be qualitatively similar in treated and untreated patients. 3. -- The proportion of altered M. leprae cells increases during the treatment, mainly with rifampicin and rifampicin + clofazimine + diaminodiphenyl sulfone. 4. -- The cell wall of M. leprae is the last bacterial structure to disappear during the degenerative process.