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Fig. 3. Loss of chick Id2 expression in a day 5.5 heart following early cardiac neural crest ablation (3–8-somite stage). Selected sections showing chick Id2 expression in a control day 5.5 heart and a day 5.5 heart after early cardiac neural crest ablation. (A, C, E, G) Expression of Id2 from proximal to distal within the developing outflow tract and heart of a control day 5.5 heart. (B, D, F, H) Loss of Id2 expression from proximal to distal within a day 5.5 outflow tract and heart following early cardiac neural crest ablation. (H) Early cardiac neural crest ablation resulted in a single outflow vessel (So) with no septation or cardiac neural crest derived condensed mesenchyme (cm). Red p and arrowhead, prong of cardiac neural crest (CNC) with Id2 expression. Blue p and arrowhead, prong of CNC with no Id2 expression. Green p and arrowhead, loss of CNC prong and Id2 expression after early CNC ablation. RV, right ventricle; LV, left ventricle; RA, right atrium; LA, left atrium; Ao, aorta; P, pulmonary trunk; PR, proximal right endocardial cushion; PL, proximal left endocardial cushion; SI, septum intermedium; DD, distal dorsal endocardial cushion; AIC, aorta intercalated endocardial cushion; PIC, pulmonary intercalated endocardial cushion; DRV, distal right ventral endocardial cushion; DLV, distal left ventral endocardial cushion; AVS, atrioventricular sulcus; So, single outflow vessel; SoR, single outflow vessel right endocardial cushion; SoL, single outflow vessel left endocardial cushion. OFT labeling based on that of Qayyum et al. (2001). |