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Glycogen accumulations in differentiating mesonephric ducts and tubuli in male human embryos
Abstract:
Human mesonephric duct epithelial cells contained empty appearing regions in the infranuclear cytoplasm when prepared for transmission electron microscopy using glutaraldehyde and osmium fixation. The same regions stained positively with PAS in Epon sections for light microscopy suggesting that glycogen was present. Incubation with saliva abolished the reaction. For electron microscopy the glycogen stained very intensely if a mixture of osmium tetroxide and potassium ferrocyanide was used instead of osmium alone. Glycogen accumulations were present between the ages of 5 to 10 weeks and absent at the age of 15 weeks. Reports by others indicate that glycogen may be present in different reactive forms in relation to its staining behaviour after various fixatives. The present results, and similar studies in other tissues, indicate that osmium tetroxide-potassium ferrocyanide fixative should be used routinely for preservation of embryos and fetuses and where indicated, for ultrastructural identification of glycogen and cytoplasmic filaments in clinical specimens.
Insights
Glycogen was identified in human embryonic kidney cells using specific microscopy techniques. This finding highlights a novel method for preserving and visualizing glycogen in developing tissues.
Area of Science:
- Embryology
- Cell Biology
- Histology
Background:
- Human mesonephric duct epithelial cells exhibit uncharacterized cytoplasmic regions.
- Periodic acid-Schiff (PAS) staining suggests the presence of glycogen in these regions.
- Glycogen's staining characteristics can vary with different fixatives.
Purpose of the Study:
- To identify and characterize the nature of the empty-appearing regions in human mesonephric duct epithelial cells.
- To evaluate the effectiveness of different fixation methods for glycogen visualization.
- To determine the developmental stage at which glycogen is present in these cells.
Main Methods:
- Transmission electron microscopy (TEM) with glutaraldehyde and osmium fixation.
- Light microscopy with PAS staining on Epon sections.
- Incubation with saliva to confirm glycogen presence.
- TEM using a mixture of osmium tetroxide and potassium ferrocyanide for enhanced glycogen staining.
Main Results:
- PAS-positive regions in light microscopy were confirmed as glycogen deposits via TEM.
- Saliva incubation abolished the PAS reaction, supporting the presence of glycogen.
- Osmium tetroxide-potassium ferrocyanide fixation significantly enhanced glycogen staining in TEM.
- Glycogen was observed in mesonephric duct cells from 5 to 10 weeks of gestation, but not at 15 weeks.
Conclusions:
- Glycogen is present in human mesonephric duct epithelial cells during specific developmental windows.
- The osmium tetroxide-potassium ferrocyanide fixative is superior for ultrastructural glycogen identification.
- This fixation method is recommended for routine preservation of embryos/fetuses and for identifying glycogen and cytoplasmic filaments in clinical specimens.