Baglaj S M, Czernik J, Kuryszko J, Kuropka P
Department of Paediatric Surgery, Wroclaw University of Medicine, Wroclaw, Poland.
J Pediatr Surg. 2001 Sep;36(9):1428-34. doi: 10.1053/jpsu.2001.26392.
The aim of this study was to evaluate a natural history of congenital intestinal atresia (IA) in the chick embryo and to assess the type and nature of changes in the intestine at various developmental stages.
Chick embryos underwent operative induction of IA on the 12th day of incubation. The procedure consisted of electrocoagulation of the mesenteric vessels supplying a 7- to 8-mm intestinal segment. The embryos were subjected to macroscopic examination, histologic and ultrastructural studies of the preatretic and postatretic bowel using the light microscope, scanning, and transmission electron microscopes. All investigations were performed in an experimental group (operated embryos), in a control group, and in a sham-operated group on the 15th, 17th, 19th, and 21st day of incubation.
The original technique of an iatrogenic "vascular event" proved to be effective because IA developed in 96% of embryos surviving the procedure. The affected portion of the bowel underwent progressive necrosis, and signs of bowel obstruction could be observed 48 hours after operation. Cord atresia (type II) developed in 81% of embryos. Histologic investigations showed progressive thinning of mucosa, flattening of mucosal folds, and epithelial detachment within the intestine proximal to atresia. There was only mild hypertrophy of the muscular layers. All these pathomorphologic changes were of rapidly progressive nature until the 17th day of incubation. Later, the rate of distension of preatretic bowel and histologic changes were less. Ultrastructural investigation of the proximal bowel showed progressive flattening of the enterocytes associated with their apical bulging, widening of the intercellular spaces, and microvilli atrophy. Surprisingly, at days 19 and 21 of incubation, signs of induction of adaptive mechanisms with partial restoration of near-normal microvilli pattern were observed.
Study of natural history of experimental IA indicates that histologic and ultrastructural lesions of the bowel are of dynamic nature and are not only the effect of pathologic intraluminal pressure.
本研究旨在评估鸡胚先天性肠闭锁（IA）的自然病史，并评估不同发育阶段肠道变化的类型和性质。
在孵化第12天对鸡胚进行IA手术诱导。该手术包括电凝供应一段7至8毫米肠段的肠系膜血管。使用光学显微镜、扫描电子显微镜和透射电子显微镜对闭锁前和闭锁后肠道进行宏观检查、组织学和超微结构研究。所有研究均在孵化第15、17、19和21天的实验组（手术胚胎）、对照组和假手术组中进行。
医源性“血管事件”的原始技术被证明是有效的，因为96%存活手术的胚胎发生了IA。肠的受累部分逐渐坏死，术后48小时可观察到肠梗阻迹象。81%的胚胎发生了索状闭锁（II型）。组织学研究显示，闭锁近端肠内黏膜逐渐变薄、黏膜皱襞变平以及上皮脱落。肌层仅有轻度肥大。直到孵化第17天，所有这些病理形态学变化都具有快速进展的性质。之后，闭锁前肠的扩张率和组织学变化较小。近端肠的超微结构研究显示肠上皮细胞逐渐变平，伴有顶端膨出、细胞间隙增宽和微绒毛萎缩。令人惊讶的是，在孵化第19和21天，观察到了适应性机制诱导的迹象，微绒毛模式部分恢复至接近正常。
实验性IA自然病史的研究表明，肠道的组织学和超微结构病变具有动态性质，且不仅仅是病理性腔内压力的作用。
