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Qualitative and quantitative differences between resident peritoneal mononuclear phagocytes of beige and control mice
Abstract:
A qualitative and quantitative comparison of resident peritoneal macrophages (RPM) from beige (C57BL6Jbg/bg), (bg), and control black (C57BL/6J), (BL), mice has been made. Giant anomalous lysosomes as described for other leukocytes are inconsistently demonstrable. The principal morphological expression of the bg phenotype in RPM is the presence of elongated dumbbell-shaped, horseshoe-shaped, and ring-formed cytoplasmic lysosomes demonstrable by electron microscopy. Detailed analysis indicates that these are probably variations of the same basic structure, a deformed biconcave disc with differences in form resulting from their being cut in various planes of section. Additional structural complexity results from fusion between adjacent lysosomes. Thus the distinctive lysosomes of bg mouse RPM are not totally analogous to those structures described in other cell types. A morphometric analysis of control RPM compared to those from bg animals shows a significant decrease in the lysosomal volume proportion from 5.8% to 5.0% (P less than 0.02) with a corresponding increase in the mitochondrial volume proportion in cells from bg animals (P less than 0.05). There are no differences between bg and controls in regard to cellular profile areas, nuclear profile areas, nuclear volume proportions, and the volume to surface ratios of either the average cell or nucleus. This study represents the first compilation by morphometric methods of total granule content in the bg animal and demonstrates the ability of these techniques to detect significant quantitative changes in cells as structurally complex as mononuclear phagocytes.
Insights
Resident peritoneal macrophages (RPM) in beige mice exhibit unique lysosome structures and altered organelle proportions compared to controls. Morphometric analysis reveals significant quantitative changes in these complex cells.
Area of Science:
- Cell Biology
- Immunology
- Genetics
Background:
- Resident peritoneal macrophages (RPM) play crucial roles in immune surveillance and tissue homeostasis.
- The beige (bg) mouse model exhibits a mutation affecting lysosome-related organelles, impacting various cell types.
- Understanding the specific cellular alterations in RPM of bg mice is essential for elucidating their function.
Purpose of the Study:
- To qualitatively and quantitatively compare RPM from beige (bg) and control (BL) mice.
- To characterize the unique lysosomal morphology in bg mouse RPM.
- To assess organelle volume proportions using morphometric analysis.
Main Methods:
- Qualitative and quantitative comparison of RPM from C57BL/6Jbg/bg (bg) and C57BL/6J (BL) mice.
- Electron microscopy to visualize and analyze lysosomal structures.
- Morphometric analysis to determine cellular and organelle volume proportions.
Main Results:
- Distinctive elongated, dumbbell-shaped, horseshoe-shaped, and ring-formed cytoplasmic lysosomes were observed in bg mouse RPM.
- These lysosomes are likely variations of a deformed biconcave disc structure, with fusion occurring between adjacent lysosomes.
- Morphometric analysis revealed a significant decrease in lysosomal volume proportion (5.8% to 5.0%) and a corresponding increase in mitochondrial volume proportion in bg RPM.
- No significant differences were found in cellular/nuclear profile areas or volume proportions between bg and control mice.
Conclusions:
- The unique lysosomal structures in bg mouse RPM are not entirely analogous to those in other cell types.
- Morphometric techniques effectively detect significant quantitative changes in complex mononuclear phagocytes.
- This study provides the first morphometric compilation of granule content in bg mice, highlighting cellular adaptations.