The pancreatic islet is a highly vascularized endocrine micro-organ. The unique architecture of rodent islets, a so-called core-mantle arrangement seen in two-dimensional images, led researchers to seek functional implications for islet hormone secretion. Three models of islet blood flow were previously proposed, all based on the assumption that islet microcirculation occurs in an enclosed structure. Recent electrophysiological and molecular biological studies using isolated islets also presumed unidirectional flow. Using intravital analysis of the islet microcirculation in mice, we found that islet capillaries were continuously integrated to those in the exocrine pancreas, which made the islet circulation rather open, not self-contained. Similarly in human islets, the capillary structure was integrated with pancreatic microvasculature in its entirety. Thus, islet microcirculation has no relation to islet cytoarchitecture, which explains its well-known variability throughout species. Furthermore, tracking fluorescent-labeled red blood cells at the endocrine-exocrine interface revealed bidirectional blood flow, with similar variability in blood flow speed in both the intra- and extra-islet vasculature. To date, the endocrine and exocrine pancreas have been studied separately by different fields of investigators. We propose that the open circulation model physically links both endocrine and exocrine parts of the pancreas as a single organ through the integrated vascular network.

中文翻译：

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综合胰腺血流：内分泌和外分泌胰腺之间的双向微循环

胰岛是高度血管化的内分泌微器官。啮齿动物胰岛的独特结构，即在二维图像中看到的所谓核-幔排列，促使研究人员寻找胰岛激素分泌的功能意义。先前提出了三种胰岛血流模型，所有模型都基于胰岛微循环发生在封闭结构中的假设。最近使用孤立胰岛的电生理学和分子生物学研究也假设单向流动。通过对小鼠胰岛微循环的活体分析，我们发现胰岛毛细血管不断地与外分泌胰腺中的毛细血管结合，这使得胰岛循环相当开放，而不是自给自足。同样在人类的胰岛中，毛细血管结构与胰腺微脉管系统完全整合。因此，胰岛微循环与胰岛细胞结构无关，这解释了其在整个物种中众所周知的变异性。此外，在内分泌-外分泌界面跟踪荧光标记的红细胞显示双向血流，胰岛内和胰岛外脉管系统的血流速度变化相似。迄今为止，内分泌和外分泌胰腺已被不同领域的研究人员分开研究。我们建议开放循环模型通过集成的血管网络将胰腺的内分泌和外分泌部分物理连接为一个器官。这解释了它在整个物种中众所周知的变异性。此外，在内分泌-外分泌界面跟踪荧光标记的红细胞显示双向血流，胰岛内和胰岛外脉管系统的血流速度变化相似。迄今为止，内分泌和外分泌胰腺已被不同领域的研究人员分开研究。我们建议开放循环模型通过集成的血管网络将胰腺的内分泌和外分泌部分物理连接为一个器官。这解释了它在整个物种中众所周知的变异性。此外，在内分泌-外分泌界面跟踪荧光标记的红细胞显示双向血流，胰岛内和胰岛外脉管系统的血流速度变化相似。迄今为止，内分泌和外分泌胰腺已被不同领域的研究人员分开研究。我们建议开放循环模型通过集成的血管网络将胰腺的内分泌和外分泌部分物理连接为一个器官。内分泌和外分泌胰腺已被不同领域的研究人员分别研究。我们建议开放循环模型通过集成的血管网络将胰腺的内分泌和外分泌部分物理连接为一个器官。内分泌和外分泌胰腺已被不同领域的研究人员分别研究。我们建议开放循环模型通过集成的血管网络将胰腺的内分泌和外分泌部分物理连接为一个器官。