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Ultrastructural changes in cells of the mouse footpad infected with Mycobacterium leprae
Abstract:
Ultrastructural changes in cells of the mouse footpad are described which occurred during the log phase of multiplication, the plateau, and the stationary phase of growth of Mycobacterium leprae.BALB/c mice were inoculated in the right hind footpad with 5 x 10(3) organisms and sacrificed in pairs at 86 to 173 days after inoculation. Tissue samples were prepared for electron microscopy by standard techniques. During the early growth phase of M. leprae in the mouse footpad, few organisms can be detected. Those present are in macrophages and are bound by a single membrane. The cytoplasm of the macrophage is less dense around the organism. There are few lysosomes, and the bacteria do not appear to be degenerating. At the peak of the growth phase, the organisms within a macrophage are bound by either a single or double membrane. There is an increased number of vacuoles, which are also bound by a double membrane, and lysosomes. During the stationary phase, most of the macrophages have taken on a vacuolar appearance and contain lysosomes. The vacuoles are bound by a double membrane, as are most of the organisms within the macrophage. Many of these organisms appear to be degenerating. Occasionally, organisms are encountered in the sarcoplasm of striated muscle. They are usually bound by a single membrane and do not appear to be degenerating.
Insights
Ultrastructural changes in mouse footpad cells reveal Mycobacterium leprae
Area of Science:
- Cell Biology
- Microbiology
- Pathology
Background:
- Mycobacterium leprae causes leprosy, a chronic infectious disease.
- Understanding M. leprae's interaction with host cells is crucial for disease control.
Purpose of the Study:
- To investigate the ultrastructural changes in mouse footpad cells during M. leprae infection.
- To characterize the cellular environment and M. leprae morphology across different growth phases.
Main Methods:
- BALB/c mice were inoculated with M. leprae in the footpad.
- Tissue samples were collected at various time points (86-173 days post-inoculation).
- Samples were analyzed using electron microscopy.
Main Results:
- Early growth phase: M. leprae in macrophages, single membrane-bound, minimal host cell damage.
- Peak growth phase: M. leprae with single/double membranes, increased host cell vacuoles and lysosomes.
- Stationary phase: Macrophages vacuolated, M. leprae often degenerating within double membranes.
Conclusions:
- M. leprae undergoes significant ultrastructural changes within host macrophages during infection.
- Host cell response evolves, with increasing vacuolation and lysosomal activity.
- Degeneration of M. leprae is observed during the stationary phase of growth.