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[Electron microscopic study of mesothelial cells in the diaphragm peritoneum of human fetus using the freeze-fracture
J Li1
1Zhejiang Branch, Hangzhou.
Abstract:
Electron microscopy of mesothelial cells from the diaphragm peritoneum of human fetuses was conducted using the freeze-fracture replica method. The results were as follows: 1) Numerous vesicles were found in single or cluster forms. The latter type was often fused with large vacuoles and opened to the free surface of the cell as secretory granules. 2) On the fractured faces of plasma and nuclear membranes, different numbers of intramembraneous particles and exocytic pores were seen on the PF surface of the plasma membrane. The diameter of the exocytic pores averaged 43 nm, and their maximum number was 26/microns2. 3) Neighboring cells were conjoined by cytoplasmic processes which were seemed to form three-dimensional intertwinings. 4) The microvilli of the mesothelial cells were grouped into three morphological classes, i.e. fork-like microvilli, bulbous ending microvilli, and stick-like microvilli. In addition, the contrast between the present investigation and the results of fine section studies on the diaphragm peritoneum of human fetus is discussed.
Insights
Freeze-fracture electron microscopy revealed secretory granules and exocytic pores in human fetal mesothelial cells. These cells also showed complex cytoplasmic interconnections and diverse microvilli morphologies.
Area of Science:
- Cell Biology
- Developmental Biology
- Histology
Context:
- The diaphragm peritoneum's mesothelial cells play a crucial role in organ protection and lubrication.
- Understanding their ultrastructure is vital for developmental biology and pathology.
- Previous studies primarily used fine sectioning, limiting detailed membrane analysis.
Purpose:
- To investigate the ultrastructure of human fetal diaphragm mesothelial cells using freeze-fracture electron microscopy.
- To characterize membrane-bound vesicles, exocytic pores, and cell-cell junctions.
- To compare freeze-fracture findings with existing fine section data.
Summary:
- Freeze-fracture electron microscopy revealed numerous vesicles, some functioning as secretory granules, within human fetal mesothelial cells.
- Exocytic pores, averaging 43 nm in diameter, were observed on the plasma membrane, with a maximum density of 26/µm².
- Cells exhibited complex three-dimensional intertwinings via cytoplasmic processes and possessed three distinct microvilli morphologies (fork-like, bulbous, stick-like).
Impact:
- Provides novel ultrastructural insights into human fetal mesothelial cell development and function.
- Highlights the utility of freeze-fracture electron microscopy for detailed membrane analysis.
- Offers a comparative basis for future studies on peritoneal mesothelial cells in health and disease.