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The mesothelium: a histochemical study of resting mesothelial cells
Abstract:
Cytochemical investigations of the resting mesothelial cells of rats are reported. The study was performed on imprint monolayers obtained from various serosal surfaces by using 3% gelatin and 1% agar-coated microscopic slides. We found only a small amount of reaction product in mesothelial cells after cytochemical demonstration of those enzymes associated with oxidative respiration; however, abundant reaction product was found when the enzymes associated with the pentose phosphate path were sought. These findings suggest that this latter respiratory mechanism may play an active role in resting mesothelial cell respiration. Enzymes associated with cell membranes such as sodium and potassium dependent ATPase and 5' nucleotidase were readily found. The "resting" mesothelial cell also had demonstrable amounts of glycogen and RNA. It is concluded that despite the morphological suggestions that the resting mesothelium is not very active metabolically (Cascarano, 1964), its histochemical profile provides good evidence of a diverse range of functional and metabolic processes. The finding of similar cytochemical profiles, irrespective of the anatomical site of the mesothelial cell sample, is considered to give credence to the concept of the mesothelium as an entity.
Insights
Resting rat mesothelial cells utilize the pentose phosphate pathway for respiration, not oxidative respiration. Histochemical analysis reveals diverse metabolic functions, supporting the mesothelium as a unified entity.
Area of Science:
- Cell Biology
- Histochemistry
- Physiology
Background:
- Mesothelial cells form the lining of serosal cavities.
- The metabolic activity of resting mesothelial cells is not well understood.
- Morphological studies suggest low metabolic activity in resting mesothelial cells.
Purpose of the Study:
- To investigate the cytochemical profile of resting rat mesothelial cells.
- To determine the primary respiratory pathways in resting mesothelial cells.
- To assess the metabolic and functional diversity of mesothelial cells.
Main Methods:
- Imprint monolayers from rat serosal surfaces were prepared.
- Cytochemical staining was used to demonstrate enzyme activity.
- Enzymes associated with oxidative respiration and the pentose phosphate pathway were investigated.
- Cell membrane enzymes, glycogen, and RNA were also assessed.
Main Results:
- Mesothelial cells showed low activity for oxidative respiration enzymes.
- Abundant activity was found for enzymes of the pentose phosphate pathway.
- Sodium and potassium dependent ATPase and 5' nucleotidase were readily detected.
- Glycogen and RNA were demonstrable in resting mesothelial cells.
Conclusions:
- The pentose phosphate pathway is likely a key respiratory mechanism for resting mesothelial cells.
- Histochemical findings indicate significant metabolic and functional activity in resting mesothelial cells, contrary to morphological suggestions.
- Consistent cytochemical profiles across different anatomical sites support the mesothelium as a singular functional entity.