Schmidt E E, MacDonald I C, Groom A C
Cell Tissue Res. 1982;225(3):543-55. doi: 10.1007/BF00214803.
The exact nature of the circulatory pathways in dog spleen, particularly with reference to the intermediate circulation and the possible existence of direct arteriovenous connections, has been studied by scanning electron microscopy (SEM) of microcorrosion casts. A new casting procedure was developed in which minimal amounts of material were injected into contracted spleens, thus filling preferentially the faster channels for flow. Extensive filling of the red pulp was thereby avoided, leaving an open view of blood vessels and their connections. The depth of focus of the SEM, incomparably greater than those of transmission electron or light microscopes, enabled vascular pathways to be traced over considerable distances. Using this approach, we have obtained clear evidence for abundant connections between arterial capillaries and venous sinuses (i.e., "closed" circulation). Typically, the terminal arteriole bifurcates repeatedly, in quick succession, giving rise to as many as twelve short capillaries, each leading directly to at least one sinus. However, an "open" circulation also exists, inasmuch as the majority of all capillaries end in the marginal zone around lymphatic nodules. In the dilated spleen, direct connections to sinuses are rarely visible but endings in the red pulp are found, in addition to those going to the marginal zone.
通过微腐蚀铸型的扫描电子显微镜（SEM）研究了犬脾脏循环途径的确切性质，特别是关于中间循环以及直接动静脉连接的可能存在情况。开发了一种新的铸型方法，即将最少量的材料注入收缩的脾脏，从而优先填充流速较快的通道。由此避免了红髓的广泛填充，使血管及其连接得以清晰呈现。SEM的焦深比透射电子显微镜或光学显微镜的焦深大得多，这使得能够追踪相当长距离的血管途径。使用这种方法，我们获得了动脉毛细血管与静脉窦之间大量连接（即“封闭”循环）的明确证据。典型情况下，终末小动脉会连续快速多次分支，产生多达十二条短毛细血管，每条毛细血管直接通向至少一个静脉窦。然而，“开放”循环也存在，因为所有毛细血管中的大多数在淋巴小结周围的边缘区终止。在扩张的脾脏中，与静脉窦的直接连接很少可见，但除了通向边缘区的那些之外，还发现有在红髓中的终末。
