Zhang Shi-Wei, Bai Yu-Zuo, Zhang Shu-Cheng, Wang Da-Jia, Zhang Tao, Zhang Dan, Wang Wei-Lin
Department of Pediatric Surgery, Shengjing Hospital, China Medical University, No 36 Sanhao St, Heping District, Shenyang 110004, PR China.
J Pediatr Surg. 2008 Aug;43(8):1452-8. doi: 10.1016/j.jpedsurg.2008.02.059.
Many patients with anorectal malformations (ARMs) continue to have postoperative anal dysfunction. The striated muscle complex (SMC) is one of the most important factors that influence defecation function. To explore the development of SMC in ARMs, the authors investigated the pelvic muscle development in rat embryos affected with ARMs.
Anorectal malformation embryos were induced by ethylenethiourea on the 10th gestational day (E10). Normal rat embryos and embryos with ARMs from E13 to E21 were serial-sectioned in the sagittal, transverse, and coronal planes, stained with H&E and immunohistochemistry staining using specific antibodies to myogenin. Temporal and spatial sequence was carried out on SMC.
On E16, in normal group, SMC appeared fibroid structure in normal rats; SMC arose from bulbocavernosus muscle and ran backward, parallel to the perineal skin, and loosely surrounded the anal canal and urethra. Although in ARM rats the rectum was absent, the location and appearance of SMC were similar to the normal group. On E18, in normal group, SMC musculature became much thicker than on E16 and SMC gave off 2 branches outside anterior to the rectum. Striated muscle complex surrounded the rectum more tightly. However, in ARM rats, obvious changes of SMC could be noted. In detail, SMC in ARMs were characterized by abnormal location, appearance, and path. Striated muscle complex shifted obviously cephalad, ventrally, and medianward and converged inferior to the rectal terminus and posterior to the urethra. The distance between SMC musculature and the perineal skin increased. This structure surrounded the fiberlike tissue posterior to the urethra. Under high-power view, there was connective tissue among intermuscular bundles, and the structure was disordered. During the following gestational days, SMC in normal and ARM groups continued their own tendency, respectively.
This study illustrated the development of the SMC in normal and ARM rats. On E16, the location and appearance of SMC in ARM rats were similar to the normal rats, and at this time, the ectopic rectal orifice could be noted. From E18 on, the maldevelopment of SMC could be observed in ARM rats. These observations suggested that the morphological changes of SMC take place after the occurrence of abnormal anorectum.
许多肛门直肠畸形（ARM）患者术后仍存在肛门功能障碍。横纹肌复合体（SMC）是影响排便功能的最重要因素之一。为了探究ARM中SMC的发育情况，作者研究了患ARM的大鼠胚胎的盆底肌肉发育。
在妊娠第10天（E10）用乙硫脲诱导肛门直肠畸形胚胎。将正常大鼠胚胎和从E13到E21的ARM胚胎在矢状面、横断面和冠状面进行连续切片，用苏木精-伊红（H&E）染色，并使用生肌调节因子特异性抗体进行免疫组织化学染色。对SMC进行时间和空间序列分析。
在E16时，正常组中，SMC在正常大鼠中呈现纤维状结构；SMC起源于球海绵体肌并向后延伸，与会阴皮肤平行，松散地围绕肛管和尿道。虽然在ARM大鼠中直肠缺失，但SMC的位置和外观与正常组相似。在E18时，正常组中，SMC肌肉组织比E16时增厚，并且SMC在直肠前方外侧发出2个分支。横纹肌复合体更紧密地围绕直肠。然而，在ARM大鼠中，可以观察到SMC有明显变化。具体而言，ARM中的SMC具有位置、外观和走行异常的特征。横纹肌复合体明显向头侧、腹侧和中线移位，并在直肠末端下方和尿道后方汇聚。SMC肌肉组织与会阴皮肤之间的距离增加。该结构围绕尿道后方的纤维状组织。在高倍视野下，肌束间有结缔组织，结构紊乱。在随后的妊娠期，正常组和ARM组的SMC分别继续各自的发育趋势。
本研究阐述了正常和ARM大鼠中SMC的发育情况。在E16时，ARM大鼠中SMC的位置和外观与正常大鼠相似，此时可注意到异位直肠开口。从E18开始，可观察到ARM大鼠中SMC发育不良。这些观察结果表明，SMC的形态学变化发生在肛门直肠异常出现之后。
