In vivo micro-imaging of mice is useful in studying the genetic basis of cardiac development in mutant embryos. We examined Phox2b^–/– mutant mice, which lack autonomic innervation to the heart and die in utero, and investigated whether this lack of innervation causes cardiac dysfunction during embryogenesis. A VisualSonics Vevo 2100 ultrahigh-frequency linear array ultrasound machine with 30- and 40-MHz probes was used to analyze embryo size, gross characteristics, ventricular contractility and rhythm. Phox2b^–/– mutant embryos underwent cessation of heartbeat and death at a greater rate than wild-type controls. We did not observe a hydrops phenotype or congenital heart defects in Phox2b^–/– mutants. Analysis of heart rhythm revealed no significant correlation with genotype. Absent these signs of a progressive pathology, we suggest that Phox2b^–/– mutant embryos likely die of sudden death secondary to acute arrhythmia. These data provide insight into the role of cardiac autonomic innervation during development.

小鼠体内显微成像可用于研究突变胚胎心脏发育的遗传基础。我们检查了Phox2b ^–/–突变小鼠，它们缺乏对心脏的自主神经支配并在子宫内死亡，并研究了这种缺乏神经支配是否会在胚胎发生过程中导致心脏功能障碍。带有 30 和 40 MHz 探头的 VisualSonics Vevo 2100 超高频线性阵列超声机用于分析胚胎大小、总体特征、心室收缩力和节律。Phox2b ^–/–突变体胚胎的心跳停止和死亡率高于野生型对照。我们没有在Phox2b 中观察到水肿表型或先天性心脏缺陷^–/–突变体。心律分析显示与基因型无显着相关性。如果没有这些进展性病理学迹象，我们认为Phox2b ^–/–突变胚胎可能死于继发于急性心律失常的猝死。这些数据提供了对心脏自主神经支配在发育过程中的作用的深入了解。