We reconstructed serial sections of a representative adult human spleen to clarify the unknown arrangement of the splenic microvasculature, such as terminal arterioles, sheathed capillaries, the red pulp capillary network and venules. The resulting 3D model was evaluated in virtual reality (VR). Capillary sheaths often occurred after the second or third branching of a terminal arteriole and covered its capillary side or end branches. The sheaths started directly after the final smooth muscle cells of the arteriole and consisted of cuboidal CD271⁺⁺ stromal sheath cells surrounded and infiltrated by B lymphocytes and macrophages. Some sheaths covered up to four sequential capillary bifurcations thus forming bizarre elongated structures. Each sheath had a unique form. Apart from symmetric dichotomous branchings inside the sheath, sheathed capillaries also gave off side branches, which crossed the sheath and freely ended at its surface. These side branches are likely to distribute materials from the incoming blood to sheath-associated B lymphocytes and macrophages and thus represent the first location for recognition of blood-borne antigens in the spleen. A few non-sheathed bypasses from terminal arterioles to the red pulp capillary network also exist. Red pulp venules are primarily supplied by sinuses, but they also exhibit a few connections to the capillary network. Thus, the human splenic red pulp harbors a primarily open microcirculation with a very minor closed part.

我们重建了具有代表性的成年人脾脏的连续切片，以阐明脾微脉管系统的未知排列，例如终末小动脉、鞘毛细血管、红髓毛细血管网络和小静脉。生成的 3D 模型在虚拟现实 (VR) 中进行评估。毛细血管鞘通常出现在终末小动脉的第二或第三分支之后并覆盖其毛细血管侧或末端分支。鞘直接在小动脉的最终平滑肌细胞之后开始，由被 B 淋巴细胞和巨噬细胞包围和浸润的立方形 CD271 ⁺⁺基质鞘细胞组成。一些鞘覆盖了多达四个连续的毛细血管分叉，从而形成奇异的细长结构。每个护套都有独特的形状。除了鞘内对称的二分分支外，鞘毛细血管还发出侧枝，这些侧枝穿过鞘并自由地终止于鞘的表面。这些侧枝很可能将输入的血液中的物质分配到鞘相关的 B 淋巴细胞和巨噬细胞，因此代表了脾脏中识别血源性抗原的第一个位置。还存在一些从终末小动脉到红髓毛细血管网络的无鞘旁路。红髓微静脉主要由鼻窦供应，但它们也与毛细血管网络有一些连接。因此，人的脾红髓具有主要开放的微循环和非常小的封闭部分。