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Cytoplasmic stress fibers in the developing heart
H Sumida1, R A Ashcraft, R P Thompson
1Department of Anatomy and Cell Biology, Medical University of South Carolina, Charleston.
The Anatomical Record
|January 1, 1989
Summary
This study reveals that filamentous actin in mesenchymal condensations plays a crucial mechanical role during embryonic heart septation in chicks and rats. These findings highlight the importance of actin dynamics in cardiac outflow tract development.
Area of Science:
- Developmental Biology
- Cell Biology
- Cardiovascular Research
Background:
- Cardiac septation is a critical process during embryonic development.
- Understanding the cellular mechanisms underlying septation is essential for identifying congenital heart defects.
Purpose of the Study:
- To investigate the distribution and role of filamentous actin during cardiac septation in embryonic chicks and rats.
- To elucidate the mechanical contribution of mesenchymal cells to the formation of the cardiac outflow tract.
Main Methods:
- Rhodamine-conjugated phalloidin staining to visualize filamentous actin.
- Histochemical and ultrastructural analysis using electron microscopy.
- Comparative study in developing chick and rat embryos.
Main Results:
- Abundant filamentous actin was observed in myocardial and mesenchymal cells within the aorticopulmonary septum of chick embryos.
- Similar actin distribution and mesenchymal condensations were noted in 14-day rat embryos.
- Electron microscopy revealed microfilament bundles in elongated mesenchymal cells and their contacts with myocytes.
Conclusions:
- Mesenchymal condensations, rich in filamentous actin, likely provide a specialized mechanical tensile function during embryonic cardiac septation.
- These findings suggest a novel role for actin-based mechanical forces in shaping the cardiac outflow channels.