创伤或肿瘤切除等可导致大范围的缺损，其损伤面常超过轴型皮瓣所能覆盖的范围。然而，皮瓣血管结合部的结构与功能尚不明了，临床上跨区切取大皮瓣时常遇到种种困惑。McGrego及Taylor等认为：相邻动脉间的吻合支逐渐变细,构成一条线状的"封闭"边界，吻合处无血液流动，特称之为阻力性血管(choke vessels)。最新资料显示吻合处有血液流动，不支持"封闭"、"阻力"学说。据此认为：1 任一choke血管都有可扩张趋势，且可控；2 可人为地改建choke血管，定向设计跨区大皮瓣。我们拟应用"原位整体标记共聚焦免疫荧光术"及"微血管直视模型"等，观测活体choke血管区域的血管密度、管径，正常与潜在开放血管之比率，以及区间动、静脉血流速度、流量及应力变化等验证以上两点假说。揭示区间的血管形态学及血流动力学之特征；探讨如何通过choke血管建立起跨区供血渠道，为临床设计跨区大皮瓣提供理论支撑。

Coverage of large, complex wounds remains a great challenge for plastic surgeons. A large soft-tissue defect caused by such things as trauma, tumor and burn is impossible to cover by one axial local flap. Up to now, the flap vascular structure and function of the junction is not clear, so the confusion has often been encountered by plastic surgeons who want to harvest a cross-boundary flap. McGregor and Taylor believed that anastomosis between adjacent arteries normally has little or no blood flow. The resistance vascular constitutes a linear "closed" border, a special term, choke vessel was named. However, our latest information indicates that anastomotic zone has blood flow, does not support the "closed" and "resistance" doctrine. We hypothesis that every choke blood vessels has dilated trend and controllable, and a cross-boundary flap can be created by the choke vessel artificially altered. In order to verify hypotheses, we plan to observe in vivo the vascular density, diameter, normal and potentially opening up blood vessels of the ratio in choke vessel zone. We will also investigate the range of arterial and venous flow speed, and stress changes in the choke area. Two different animal modes will be use to test the hypotheses,"intravital fluorescent staining with tissue clearing in displaying microvascular architecture"and"The observation chamber technique for in vivo study of the choke anastomotic region". Purposes of this study are to rreveal the vascular morphology and hemodynamic characteristics, and provide a theoretical foundation for designning a large flap in clinical by explore how to dilate choke vascular and establish the blood supply channels to cross-boundary flap.