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Figure 2
The zebrafish heart: anatomy, histology, and injury paradigms. (A) Schematic representation of the anatomical position of the heart in the adult zebrafish. The teleost heart is composed of a single atrium and a single ventricle. Blood exits the heart through the bulbus arteriosus, an elastic, non‐contractile chamber composed of smooth muscle. (B) Histological organization of the adult zebrafish ventricle. Cardiac muscle is covered externally by the epicardium and internally by the endocardium. The myocardium is divided into three distinctive populations: trabecular, primordial, and cortical. The cortical myocardium is highly irrigated by coronary vessels. Endothelial cells from the coronary vasculature are frequently surrounded by pericytes. For simplicity, the presence of fibroblasts in the uninjured heart has been omitted. (C) Apex amputation removes ∼20% of the ventricle and leads to the formation of a fibrin clot. (D) Cryoinjury induces local tissue necrosis (∼20% of the ventricle) and triggers apoptosis. (E) Cardiomyocyte genetic ablation causes diffuse loss of ∼60% of cardiomyocytes in the heart, while preserving the remaining cell types. (F) Hypoxia/reoxygenation induces low levels of diffuse cell death in all cell types of the heart. Ant, anterior; AT, atrium; BA, bulbus arteriosus; CM, cardiomyocyte; CV, coronary vasculature; Dor, dorsal; EC, endocardium; EP, epicardium; M, myocardium; Post, posterior; V, ventricle; Ven, ventral