Stevenson R E, Jones K L, Phelan M C, Jones M C, Barr M, Clericuzio C, Harley R A, Benirschke K
Pediatrics. 1986 Sep;78(3):451-7.
Dissection of the abdominal vasculature in 11 cases of sirenomelia has demonstrated a pattern of vascular abnormalities that explains the defects usually found in this condition. The common feature is the presence of a single large artery, arising from high in the abdominal cavity, which assumes the function of the umbilical arteries and diverts nutrients from the caudal end of the embryo distal to the level of its origin. The steal vessel derives from the vitelline artery complex, an early embryonic vascular network that supplies the yolk sac. Arteries below the level of this steal vessel are underdeveloped and tissues dependent upon them for nutrient supply fail to develop, are malformed, or arrest in some incomplete stage. In contrast to the prevailing view that sirenomelia arises by posterior fusion of the two developing lower limbs, these studies suggest that the single lower extremity in sirenomelia arises from failure of the lower limb bud field to be cleaved into two lateral masses by an intervening allantois.
对11例并腿畸形病例的腹部血管系统进行解剖后发现，血管异常模式能够解释该病通常出现的缺陷。其共同特征是存在一条粗大的单一动脉，该动脉起源于腹腔较高位置，承担脐动脉的功能，并将营养物质从胚胎起源水平远端的尾端转移。窃取血管源自卵黄动脉复合体，这是一个供应卵黄囊的早期胚胎血管网络。在这条窃取血管水平以下的动脉发育不全，依赖这些动脉获取营养供应的组织无法发育、出现畸形或在某个不完全阶段停滞发育。与普遍认为并腿畸形是由两条发育中的下肢后部融合引起的观点不同，这些研究表明，并腿畸形中的单一下肢是由于下肢芽基未能被中间的尿囊分割成两个外侧团块所致。
