胚胎发育中形成的盆腔与腹膜后筋膜间隙是先天最优外科手术平面。在正确筋膜间隙内精准分离可以提高手术疗效并减少手术并发症。然而，由于对胚胎发育过程中结肠系膜—原始壁层腹膜--肾筋膜间的融合机制认识不清，全结肠系膜切除(Complete mesocolic excision, CME)和根治性肾切除（radical nephrectomy, RN）的手术平面一直存在争议。我们依据前期成人标本研究结果推测“结肠系膜—原始壁层腹膜--肾筋膜间可能并没有完全融合；肾后筋膜外层可能源自原始壁层腹膜折叠并完全融合；肾筋膜内层是真正的肾筋膜”。本研究将采用改良的解剖和组织学方法，序贯观察胚胎发育中升降结肠系膜—原始壁层腹膜--肾筋膜的融合过程，探索融合机制。以期①阐明升降结肠后方与肾脏周围筋膜的胚胎学本质；②精准定位CME和RN的手术平面并完善手术平面的解剖学理论；③探索融合机制解剖学研究的方法。

The pelvic and retroperitoneal fascia spaces forming during embryonic development are the natural and superior surgical planes. Precise surgical dissection in the correct fascia spaces can improve the surgical effects and reduce the complications. While because of the unclear mechanism of embryological fascial fusion among the bilateral mesocolon--primitive parietal retroperitoneum--renal fascia, it is still controversial about the surgical planes of complete mesocolic excision (CME) and radical nephrectomy (RN) nowadays. Based on our previous anatomical researches on adult cadavers, we speculate that no complete fusion among the ascending and descending mesocolon--primitive parietal retroperitoneum--renal fascia may happen, the outer layer of posterior renal fascia may come from the complete fusion of the folded retroperitoneum and inner layer of renal fascia may be the real renal fascia forming in the embryonic development of the kidney. In this study we combine modified anatomical and histological methods to observe the process of fusion among the bilateral mesocolon--primitive parietal retroperitoneum--renal fascia and explore the mechanism of fusion in fetuses with sequential fetal ages. We aim to ①clarify the embryological natures of the fascia posterior to the bilateral mesocolon those around the kidney. ②precise locate surgical plane of CME and RN and improve their anatomical theory. ③explore the methods of anatomical research on the mechanism of fascial fusion.