Baumgarten H G, Moritz F, Schlossberger H G
Prog Clin Biol Res. 1981;59A:187-96.
14C-5,6-DHT-Melanin, a labelled synthetic polymer resembling the naturally occurring melanin formed in brain by autoxidation of dopamine, was injected into the left lateral ventricle of adult rats, and its fate followed by autoradiography and by transmission electron microscopy of structures identified as labelled in preceding light micrographs, and by EM-autoradiography. Shortly after injection, melanin particles (easily identified in the em because of their size, structure and electron opacity) were seen ingested by supraependymal and epiplexus cells, by cells residing in the piaarachnoid, i.e. free subarachnoidal cells and perivascular cells, and by subependymally located microglia-like cells with intraventricular processes. Up to day four, an increase in the number of labelled phagocytes in the CSF was noted which transformed into typical reactive macrophages. Beyond this time, many intraventricular melanin-loaded phagocytes formed rounded clusters; cells of such clusters were subsequently found to invade the brain parenchyma by penetrating the ependymal lining and to accumulate in the perivascular space of brain vessels. 14C-Melanin-storing macrophages were found in the marginal sinus of the deep jugular lymph nodes suggesting emigration of CNS-derived phagocytes via lymphatics or prelymphatics that contact the subarachnoidal space compartment. This does not exclude the possibility that some of the macrophages leave the brain via the systemic circulation by penetrating the vascular endothelium; these may be disposed of in peripheral organs other than the lymph nodes. The ability of supraependymal, epiplexus, free subarachnoidal and perivascular cells in the pia and of subependymal microglia cells to accumulate synthetic melanin by phagocytosis suggests that these cells are local variants of the same type of resting potential phagocytes of the mammalian brain. The CSF appears to be replenished with phagocytes by mitosis and migration of microglia-like cells or their precursors located underneath the ependyma of the lateral ventricle and by mitosis of resting intrathecal cells.
14C - 5,6 - 二氢睾酮 - 黑色素是一种标记的合成聚合物，类似于多巴胺在大脑中通过自氧化形成的天然黑色素。将其注入成年大鼠的左侧脑室，通过放射自显影以及对先前光学显微镜照片中标记结构进行透射电子显微镜观察和电子显微镜放射自显影来追踪其去向。注射后不久，可见黑色素颗粒（因其大小、结构和电子不透明度在电子显微镜下易于识别）被室管膜上细胞和丛状细胞、位于软脑膜蛛网膜中的细胞（即游离蛛网膜下腔细胞和血管周细胞）以及具有脑室内突起的室管膜下微胶质样细胞吞噬。直至第4天，脑脊液中标记吞噬细胞数量增加，这些细胞转变为典型的反应性巨噬细胞。在此之后，许多脑室内负载黑色素的吞噬细胞形成圆形簇；随后发现此类簇中的细胞通过穿透室管膜内衬侵入脑实质并积聚在脑血管的血管周间隙中。在颈深部淋巴结的边缘窦中发现了储存14C - 黑色素的巨噬细胞，这表明中枢神经系统来源的吞噬细胞通过与蛛网膜下腔隔室接触的淋巴管或前淋巴管迁移。这并不排除一些巨噬细胞通过穿透血管内皮经体循环离开大脑的可能性；这些巨噬细胞可能在淋巴结以外的外周器官中被清除。室管膜上、丛状、游离蛛网膜下腔和软脑膜血管周细胞以及室管膜下微胶质细胞通过吞噬作用积累合成黑色素的能力表明，这些细胞是哺乳动物大脑中同一类型静息电位吞噬细胞的局部变体。脑脊液似乎通过位于侧脑室室管膜下方的微胶质样细胞或其前体的有丝分裂和迁移以及静息鞘内细胞的有丝分裂来补充吞噬细胞。
