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Cell surface changes during cleavage of newt eggs: scanning electron microscopic studies
Journal of Embryology and Experimental Morphology
|February 1, 1985
Summary
Cell surface changes during newt egg cleavage reveal membrane growth occurs in both pigmented and unpigmented areas. Stable cell junctions form through lamellipodia interactions, crucial for embryonic development.
Area of Science:
- Developmental Biology
- Cell Biology
- Embryology
Background:
- The first cleavage of eggs is a critical stage in embryonic development.
- Understanding cell surface dynamics is essential for comprehending early embryonic morphogenesis.
Purpose of the Study:
- To investigate the dynamic changes of the cell surface during the first cleavage of Cynopus (Triturus) pyrrhogaster eggs.
- To elucidate the mechanisms of membrane growth and intercellular junction formation during early embryonic cell division.
Main Methods:
- Scanning electron microscopy (SEM) was employed to visualize cell surface alterations.
- Carbon marking experiments were conducted to trace membrane movement and growth patterns.
Main Results:
- SEM revealed a dense population of elongated microvilli initially along the cleavage furrow.
- Membrane growth was observed in both presumptive unpigmented and adjacent pigmented areas.
- Stable intercellular junctions formed via successive lamellipodia interactions, including filopodia contact and body fusion.
- In demembranated eggs, lamellipodia persisted individually, and cytoplasmic threads indicated cell contact.
Conclusions:
- Membrane expansion during early cleavage is not restricted to the unpigmented surface.
- The formation of stable intercellular junctions is a multi-step process involving direct cell-cell adhesion via lamellipodia.
- Cytoplasmic threads play a role in maintaining cell contact during cleavage, even in the absence of a complete membrane.