atrioventricular canal development

Definition

Target type: biologicalprocess

The progression of the atrioventricular canal over time, from its formation to the mature structure. The atrioventricular canal is the part of the heart connecting the atrium to the cardiac ventricle. [GOC:BHF, GOC:gr, PMID:14701881, UBERON:0002087, ZFA:0001315]

The atrioventricular (AV) canal is a critical structure during early heart development that gives rise to the atrioventricular valves (mitral and tricuspid) and the surrounding fibrous tissues. Its formation involves a complex interplay of genetic and cellular mechanisms, leading to the proper separation of the atria and ventricles. Here's a detailed breakdown of the process:

1. **Early Heart Tube Formation:** The heart begins as a simple tube, with the AV canal located at the junction between the primitive atria and ventricles.

2. **Endocardial Cushion Formation:** Specialized mesenchyme cells from the endocardial lining of the heart tube migrate into the AV canal, forming two endocardial cushions, one on each side of the canal. These cushions are essential for guiding the flow of blood and forming the valves.

3. **Fusion of Endocardial Cushions:** The endocardial cushions grow and fuse, eventually dividing the AV canal into the right and left atrioventricular openings.

4. **Valvular Formation:** The endocardial cushions differentiate into valve leaflets, the thin, flap-like structures that control blood flow through the valves.

5. **Fibrous Tissue Development:** The tissue surrounding the valves matures into fibrous tissue, providing structural support and ensuring the valves function properly.

6. **Ventricular Septal Development:** Concurrently with AV canal development, the ventricular septum is forming. This process is essential for separating the left and right ventricles and ensuring proper blood circulation.

7. **Growth and Remodeling:** Throughout the development process, the AV canal undergoes significant growth and remodeling, adapting to the increasing size and function of the heart.

Factors crucial for successful AV canal development include:

* **Signaling Pathways:** Multiple signaling pathways, including BMP, TGF-beta, Wnt, and FGF, are involved in regulating cell proliferation, differentiation, and migration during AV canal formation.
* **Transcription Factors:** Specific transcription factors, such as NKX2-5, GATA4, and TBX5, play vital roles in orchestrating gene expression and cellular fate determination.
* **Extracellular Matrix:** The composition and organization of the extracellular matrix surrounding the AV canal are critical for cell adhesion, migration, and differentiation.

Disruptions in any of these steps can lead to various congenital heart defects affecting the AV valves, including:

* **Atrioventricular Septal Defect (AVSD):** A hole in the septum separating the atria and ventricles.
* **Endocardial Cushion Defect (ECD):** Abnormal development of the endocardial cushions, resulting in valve abnormalities.
* **Double Outlet Right Ventricle (DORV):** A condition where both great arteries (aorta and pulmonary artery) arise from the right ventricle.

Understanding the intricate developmental process of the AV canal is crucial for diagnosing, treating, and potentially preventing congenital heart defects. Ongoing research is focused on identifying new therapeutic targets and developing novel approaches for managing these conditions.'
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