Männer J, Seidl W, Steding G
Abteilung Embryologie, Universität Göttingen, Germany.
Anat Embryol (Berl). 1995 Jan;191(1):61-72. doi: 10.1007/BF00215298.
The present study was designed to investigate whether the formation of the cranial flexure is involved in the normal positional changes of the embryonic heart tube that occur during its transformation from the c- to s-shaped loop. For this purpose, the formation of the cranial flexure was locally suppressed in chick embryos by introducing a straight hair into the neural canal. In the experimental embryos, prevention of cranial flexure did not suppress the normal positional changes of the heart tube. However, other anomalies in the looping of the heart tube were frequently observed. These anomalies were caused by alterations in the formation of the ventral thoracic wall, which in turn seemed to be related not to the prevention of the cranial flexure but rather to accidental injuries during the implantation of the hair. In the embryos with abnormal looping of the heart tube, the incidence of delayed/defective septation of the heart was significantly higher than in embryos with normal looping. These results show that in the chick embryo: (1) cranial flexure is not involved in normal positional changes of the heart loop; (2) manipulations at the head region of the embryo can unintentionally result in developmental disorders of the ventral thoracic wall; (3) such disorders can result in congenital heart defects through mechanical interference with normal looping of the embryonic heart. The possible significance of these findings for the evaluation of experimental studies of chick embryos is discussed in the context of anomalies observed after surgical ablation of the premigratory cranial neural crest.
本研究旨在探讨颅曲的形成是否参与胚胎心脏管从c形环向s形环转变过程中发生的正常位置变化。为此，通过将一根直发插入神经管，在鸡胚中局部抑制颅曲的形成。在实验胚胎中，阻止颅曲并未抑制心脏管的正常位置变化。然而，经常观察到心脏管环化的其他异常情况。这些异常是由胸腹壁腹侧形成的改变引起的，而这反过来似乎与阻止颅曲无关，而是与植入毛发过程中的意外伤害有关。在心脏管环化异常的胚胎中，心脏间隔延迟/缺陷的发生率显著高于环化正常的胚胎。这些结果表明，在鸡胚中：(1)颅曲不参与心脏环的正常位置变化；(2)对胚胎头部区域的操作可能无意中导致胸腹壁腹侧的发育障碍；(3)这种障碍可通过对胚胎心脏正常环化的机械干扰导致先天性心脏缺陷。在迁移前颅神经嵴手术切除后观察到的异常情况下，讨论了这些发现对鸡胚实验研究评估的可能意义。
