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Electron microscopic observations of intracytoplasmic inclusions in human and murine leprosy bacilli
Abstract:
The intracytoplasmic inclusions of Mycobacterium leprae in human lepromata and M. lepraemurium in murine lepromata were studied in ultrathin serial sections at the electron microscopic level. The inclusions were mostly homogeneous and spherical, and did not exist uniformly throughout the bacillary cells. They did not appear to be delimited by membranous structures and apparently had no internal structure. There seemed to be fundamentally little difference between M. leprae and M. lepraemurium in the fine structure of these inclusions. However, the large diffuse inclusions observed in the cells of M. lepraemurium may be a special feature of murine bacilli.
Insights
Electron microscopy revealed intracytoplasmic inclusions in Mycobacterium leprae and M. lepraemurium. These inclusions, largely homogeneous and lacking membranes, showed minimal differences between human and murine bacilli, with diffuse inclusions potentially unique to M. lepraemurium.
Area of Science:
- Microbiology
- Cell Biology
- Electron Microscopy
Background:
- Mycobacterium leprae causes leprosy in humans, while M. lepraemurium infects rodents.
- Intracytoplasmic inclusions within these bacteria have been observed but not fully characterized at the ultrastructural level.
- Understanding bacterial ultrastructure can provide insights into pathogen biology and host-pathogen interactions.
Purpose of the Study:
- To investigate the ultrastructure of intracytoplasmic inclusions in Mycobacterium leprae and M. lepraemurium using electron microscopy.
- To compare the fine structure of these inclusions between the human and murine bacterial species.
- To identify any unique features of inclusions in M. lepraemurium.
Main Methods:
- Ultrathin serial sections of human lepromata infected with M. leprae and murine lepromata infected with M. lepraemurium were prepared.
- Samples were examined using transmission electron microscopy to analyze the morphology and structure of intracytoplasmic inclusions.
- Detailed ultrastructural analysis focused on the shape, size, homogeneity, and presence of surrounding membranes.
Main Results:
- Intracytoplasmic inclusions in both M. leprae and M. lepraemurium were predominantly homogeneous and spherical.
- These inclusions were not uniformly distributed within the bacterial cells.
- No delimiting membranous structures or internal substructures were observed within the inclusions.
- Large, diffuse inclusions were noted in M. lepraemurium, suggesting a potential species-specific characteristic.
Conclusions:
- The fine structure of intracytoplasmic inclusions in M. leprae and M. lepraemurium shows fundamental similarities.
- The absence of membranes and internal structure in these inclusions is a consistent finding.
- Large diffuse inclusions may represent a distinctive feature of M. lepraemurium within murine host cells.