Calcium containing lysosomes in the normal chick duodenum: a histochemical and analytical electron microscopic study

Area of Science:

• Cell Biology
• Gastroenterology
• Mineral Metabolism

Background:

• Absorptive cells in the chick duodenum exhibit supranuclear vesicular structures.
• These vesicles possess granular content and undergo exocytosis.

Purpose of the Study:

• To investigate the composition and function of supranuclear vesicles in chick duodenal absorptive cells.
• To determine the role of these vesicles in calcium transport.

Main Methods:

• Transmission electron microscopy to visualize vesicular structures.
• High-temperature microincineration to assess mineral content.
• Osmium pyroantimonate staining and EGTA chelation to identify calcium.
• X-ray microanalysis for intravesicular calcium localization.
• Acid phosphatase staining to identify lysosomal enzymes.

Main Results:

• Supranuclear vesicles are membrane-bound with granular contents.
• Granules are mineral-containing and resistant to heat.
• Vesicles show high calcium concentration and intravesicular localization.
• Vesicles are positive for the lysosomal enzyme acid phosphatase.

Conclusions:

• Supranuclear vesicles in chick duodenal cells are calcium-rich lysosomes.
• These vesicles are potentially involved in the transcellular transport of calcium ions.