Vassall-Adams P R
J Anat. 1982 Mar;134(Pt 2):209-14.
The form and position of the developing atrioventricular bundle and its branches has been studied in the hearts of domestic fowl embryos operated upon to induce delayed closure of the interventricular foramen. The operation was performed at 3 days of incubation when the outflow tract of the tubular heart was temporarily distorted by placing a nylon rod beneath the tract for 48 hours. The hearts from operated embryos were sectioned serially and examined with the light microscope at 11 days of incubation; normal hearts of the same incubation age were available for comparison. Small ventricular septal defects were found in a proportion of the operated hearts, and the form and position of developing conducting tissue with relation to the defects was of particular significance. The atrioventricular bundle and the septal component of the ring branch were represented by discrete fasciculi, but the right and left limbs of the bundle were disposed as a drape of tissue overlying the crest of the developing muscular septum, and situated beneath both the ventricular septal defect and cushion tissue of the septal truncus ridge. These observations of the developing conducting tissue in operated hearts are compatible with the concept that the bundle and branches develop normally from part of a precursor tissue distributed as a complete subendocardial sleeve in the tubular heart. They also imply that in the normal adult avian heart the positions of the atrioventricular bundle and its branches denote the junctional zones of the components forming the ventricular septum.
在对家鸡胚胎心脏进行手术以诱导室间孔延迟关闭的实验中，研究了正在发育的房室束及其分支的形态和位置。手术在孵化第3天进行，通过在流出道下方放置尼龙棒48小时，使管状心脏的流出道暂时变形。将手术胚胎的心脏连续切片，并在孵化第11天用光学显微镜检查；同时获取相同孵化年龄的正常心脏用于比较。在部分手术心脏中发现了小的室间隔缺损，发育中的传导组织相对于缺损的形态和位置具有特别重要的意义。房室束和环分支的间隔成分由离散的束状结构代表，但束的左右分支呈组织帘状，覆盖在正在发育的肌性间隔嵴上，位于室间隔缺损和间隔干嵴的垫状组织下方。对手术心脏中发育中的传导组织的这些观察结果与以下概念相符，即束和分支正常发育自作为管状心脏中完整的心内膜下套分布的前体组织的一部分。它们还意味着，在正常成年禽心脏中，房室束及其分支的位置表示形成室间隔的各成分的交界区。
