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A freeze-etching study on experimental murine mastitis
Abstract:
Streptococcal mastitis was produced experimentally in mice inoculated by the intramammary route; freeze-etched preparations from the affected mammary glands were studied by electron microscopy. The inoculated cocci were seen free in the acinar lumen, within luminal phagocytes and within cells of the epithelium. No significant pathological changes were noted in the junctional complexes between secretory epithelial cells. The results were comparable to those obtained by ultrathin sectioning and indicated that, while cocci can transfer from the acinar lumen into the substance of the epithelium and towards a subepithelial location, the junctional complexes between epithelial cells present a potential barrier to movement through the intercellular spaces.
Insights
Streptococcal mastitis research in mice shows bacteria can enter mammary epithelial cells. However, cell junctions act as a barrier, limiting bacterial spread through intercellular spaces.
Area of Science:
- Microbiology
- Pathology
- Electron Microscopy
Background:
- Mastitis is a significant concern in mammary gland health.
- Streptococcal infections are a common cause of mastitis.
- Understanding bacterial invasion mechanisms is crucial for treatment.
Purpose of the Study:
- To investigate the cellular pathway of *Streptococcus* invasion in experimentally induced mastitis.
- To evaluate the role of epithelial junctional complexes as a barrier to bacterial spread.
Main Methods:
- Experimental induction of streptococcal mastitis in mice.
- Intramammary inoculation with *Streptococcus* bacteria.
- Electron microscopy, including freeze-etching and ultrathin sectioning, of affected mammary gland tissue.
Main Results:
- Inoculated *Streptococcus* were observed within the acinar lumen, phagocytes, and epithelial cells.
- No significant pathological changes were detected in the junctional complexes between secretory epithelial cells.
- Bacteria demonstrated potential to move from the lumen into the epithelium and towards subepithelial areas.
Conclusions:
- Epithelial junctional complexes represent a potential barrier to intercellular bacterial movement during mastitis.
- Electron microscopy provides detailed insights into bacterial-host cell interactions in mammary glands.
- Further research may explore strategies to enhance these epithelial barriers.