Munshi J S D, Ghosh T K, Ojha J, Olson K R
P.G. Department of Zoology, Bhagalpur University, Bhagalpur 812007, India.
Indiana University School of Medicine, South Bend Center, University of Notre Dame, Notre Dame, Indiana 46556.
J Morphol. 1990 Feb;203(2):181-201. doi: 10.1002/jmor.1052030206.
Methyl methacrylate vascular corrosion replicas were used to examine the macrocirculation in the head region and the microcirculation of respiratory vessels in the air-breathing swamp eel Monopterus cuchia. Fixed respiratory tissue was also examined by SEM to verify capillary orientation. The respiratory and systemic circulations are only partially separated, presumably resulting in supply of mixed oxygenated and venous blood to the tissues. A long ventral aorta gives rise directly to the coronary and hypobranchial arteries. Two large shunt vessels connect the ventral aorta to the dorsal aorta, whereas the remaining ventral aortic flow goes to the respiratory islets and gills. Only two pairs of vestigial gill arches remain, equivalent to the second and third arches, yet five pairs of aortic arches were identified. Most aortic arches supply the respiratory islets. Respiratory islet capillaries are tightly coiled spirals with only a fraction of their total length in contact with the respiratory epithelium. Valve-like endothelial cells delimit the capillary spirals and are unlike endothelial cells in other vertebrates. The gills are highly modified in that the lamellae are reduced to a single-channel capillary with a characteristic three-dimensional zig-zag pathway. There are no arterio-arterial lamellar shunts, although the afferent branchial artery supplying the gill arches also supplies respiratory islets distally. A modified interlamellar filamental vasculature is present in gill tissue but absent or greatly reduced in the respiratory islets. The macro- and micro-circulatory systems of M. cuchia have been considerably modified presumably to accommodate aerial respiration. Some of these modifications involve retention of primitive vessel types, whereas others, especially in the microcirculation, incorporate new architectural designs some of whose functions are not readily apparent.
甲基丙烯酸甲酯血管铸型被用于研究呼吸空气的黄鳝（Monopterus cuchia）头部区域的大循环和呼吸血管的微循环。还通过扫描电子显微镜（SEM）检查固定的呼吸组织，以验证毛细血管的方向。呼吸循环和体循环仅部分分离，推测这会导致混合的含氧血和静脉血供应到组织。一条长的腹主动脉直接发出冠状动脉和鳃下动脉。两条大的分流血管将腹主动脉与背主动脉相连，而其余的腹主动脉血流则流向呼吸小叶和鳃。仅保留了两对退化的鳃弓，相当于第二和第三鳃弓，但识别出了五对主动脉弓。大多数主动脉弓为呼吸小叶供血。呼吸小叶毛细血管是紧密盘绕的螺旋状，其总长度中只有一小部分与呼吸上皮接触。瓣膜状内皮细胞界定了毛细血管螺旋，与其他脊椎动物的内皮细胞不同。鳃经过高度改造，鳃片减少为单通道毛细血管，具有独特的三维之字形路径。虽然供应鳃弓的入鳃动脉也向远端的呼吸小叶供血，但没有动脉-动脉鳃片分流。鳃组织中存在一种经过改造的鳃片间丝状脉管系统，但在呼吸小叶中不存在或大大减少。黄鳝的大循环和微循环系统已经有了很大的改变，大概是为了适应空气呼吸。其中一些改变涉及保留原始血管类型，而其他改变，尤其是在微循环中，采用了新的结构设计，其中一些功能并不容易显现。
