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Absorption activity and barrier properties in the endolymphatic sac. Ultrastructural and morphometric analysis
H Hoshikawa1, H Furuta, N Mori
1Department of Otolaryngology, Kagawa Medical School, Japan.
Acta Oto-Laryngologica
|January 1, 1994
Summary
The endolymphatic sac epithelium acts as a tight barrier, with specific cells in the intermediate and distal portions actively absorbing macromolecules like horseradish peroxidase (HRP).
Area of Science:
- Oto-rhino-laryngology
- Cell Biology
- Physiology
Background:
- The endolymphatic sac (ES) plays a crucial role in inner ear fluid homeostasis.
- Understanding the absorptive and barrier functions of the ES epithelium is vital for inner ear research.
Purpose of the Study:
- To investigate the absorption activity and barrier properties of the guinea pig endolymphatic sac (ES) epithelium.
- To identify specific cell types and regions within the ES involved in macromolecular uptake.
Main Methods:
- Horseradish peroxidase (HRP) was injected into the ES lumen of guinea pigs.
- Ultrastructural and morphometric analysis was performed 1-10 hours post-injection.
- Absorption and barrier functions were assessed at cellular and regional levels.
Main Results:
- Epithelial cells in the proximal ES showed no HRP absorption.
- Two types of absorptive cells (active and non-active) were identified in the intermediate portion.
- Both intermediate and distal portions demonstrated macromolecular absorption, with varying activity over time.
- No HRP penetrated the epithelial lining, indicating a tight barrier.
Conclusions:
- The intermediate and distal portions of the ES epithelium are actively involved in macromolecular absorption.
- Specific absorptive cells within the ES epithelium play a key role in this process.
- The ES epithelium forms a robust barrier, preventing intraluminal macromolecules from entering deeper tissues.