Shafik A, Doss S, Asaad S, Ali Y A
Department of Surgery and Experimental Research, Faculty of Medicine, Cairo University, Egypt.
Int J Colorectal Dis. 1999 Nov;14(4-5):237-44. doi: 10.1007/s003840050217.
The existence of a sphincter at the rectosigmoid junction (RSJ) is controversial. Recent studies have demonstrated a high-pressure zone within the RSJ which responds to sigmoid colon or rectal contractions by relaxation or contraction, respectively. These findings suggest the presence of a "physiological" sphincter at the RSJ. The current study investigated the anatomical and histological structure and the radiological picture of the RSJ in view of the possible existence of an anatomical sphincter at the RSJ and elucidating its function. The RSJ was studied in 28 cadavers (18 adults and 10 fully mature neonates) by dissection. A histological study of the RSJ was performed in 5 cadavers. Radiological examination using double-contrast barium enema was carried out in 50 healthy volunteers (mean age 44.2+/-14.4 years; 32 men, 18 women). The mucous membrane of the RSJ was found in folds forming a "mucosal rosette" of a mean length of 2.8+/-0.9 cm in adult specimens and 0.7+/-0.2 cm in neonates. The distal end of the mucosal rosette was sharply delineated and in some specimens protruded into the rectal lumen as a small nipple, which was surrounded by a "rectal fornix" on either side. The histological examination of the RSJ showed mucosal foldings with deep crypts surrounded by lymphocytic aggregates and marginated by muscularis mucosa. The circular muscle coat showed gradually increasing thickness towards the rectum. Nerve cells in the submucosa were located at three levels: in the vicinity of the muscularis mucosa, in the middle of the submucosa, and in the proximity of the circular muscle. Radiologically the opening of the sigmoid colon into the RSJ presented as a ring or crescent. Radiological striations representing the mucosal rosette were demonstrated. The RSJ appeared as a narrow contractile segment. The anatomical, histological, and radiological findings thus indicate that the RSJ is a segment which can be identified by its interior rather than outer aspect. The study suggests the presence of an anatomical sphincter at the RSJ which seems to regulate the passage of stools from the sigmoid colon to the rectum.
直肠乙状结肠交界处（RSJ）是否存在括约肌存在争议。最近的研究表明，RSJ内存在一个高压区，它分别通过舒张或收缩对乙状结肠或直肠的收缩作出反应。这些发现提示RSJ存在“生理性”括约肌。鉴于RSJ可能存在解剖学上的括约肌并阐明其功能，本研究调查了RSJ的解剖结构、组织学结构及放射影像学表现。通过解剖研究了28具尸体（18例成人和10例足月新生儿）的RSJ。对5具尸体的RSJ进行了组织学研究。对50名健康志愿者（平均年龄44.2±14.4岁；32名男性，18名女性）进行了双重对比钡灌肠放射学检查。发现RSJ的黏膜呈褶皱状形成“黏膜玫瑰花结”，在成人标本中平均长度为2.8±0.9cm，在新生儿中为0.7±0.2cm。黏膜玫瑰花结的远端界限清晰，在一些标本中作为一个小乳头突入直肠腔，两侧被“直肠穹窿”围绕。RSJ的组织学检查显示黏膜褶皱，深部隐窝被淋巴细胞聚集物包围，肌黏膜为边缘。环形肌层向直肠方向厚度逐渐增加。黏膜下层的神经细胞位于三个层面：肌黏膜附近、黏膜下层中部和环形肌附近。在放射学上，乙状结肠进入RSJ的开口呈环形或新月形。显示出代表黏膜玫瑰花结的放射状条纹。RSJ表现为一个狭窄的收缩段。因此，解剖学、组织学和放射学研究结果表明，RSJ是一个可通过其内部而非外部特征识别的节段。该研究提示RSJ存在解剖学上的括约肌，它似乎调节粪便从乙状结肠向直肠的通过。
