Navascués J, Moujahid A, Almendros A, Marin-Teva J L, Cuadros M A
Departamento de Biología Celular, Facultad de Ciencias, Universidad de Granada, Spain.
J Comp Neurol. 1995 Apr 3;354(2):209-28. doi: 10.1002/cne.903540205.
The origin, migration, and differentiation of microglial precursors in the avascular quail retina during embryonic and posthatching development were examined in this study. Microglial precursors and developing microglia were immunocytochemically labeled with QH1 antibody in retinal whole mounts and sections. The retina was free of QH1+ macrophages at embryonic day 5 (E5). Ameboid QH1+ macrophages from the pecten entered the retina from E7 on. These macrophages spread from central to peripheral areas in the retina by migrating on the endfeet of the Müller cells and reached the periphery of the retina at E12. While earlier macrophages were migrating along the inner limiting membrane, other macrophages continued to enter the retina from the pecten until hatching (E16). From E9 on, macrophages were seen to colonize progressively more scleral retinal layers as development advanced. Macrophages first appeared in the ganglion cell layer at E9, in the inner plexiform layer at E12, and in the outer plexiform layer at E14. Therefore, it seems that macrophages first migrated tangentially along the inner retinal surface and then migrated from vitreal to scleral levels to gain access to the plexiform layers, where they differentiated into ramified microglia. Macrophages appeared to differentiate shortly after arrival in the plexiform layers, as poorly ramified QH1+ cells were seen as early as E12 in the inner plexiform layer and at E14 in the outer plexiform layer. Radial migration of macrophages toward the outer plexiform layer continued until posthatching day 3, after which retinal microglia showed an adult distribution pattern. We also observed numerous vitreal macrophages intimately adhered to the surface of the pecten during embryonic development, when macrophages migrated into the retina. These vitreal macrophages were not seen from hatching onwards, when no further macrophages entered the retina.
本研究检测了胚胎期和孵化后鹌鹑无血管视网膜中微胶质前体细胞的起源、迁移和分化。在视网膜整装片和切片中，用QH1抗体对微胶质前体细胞和发育中的小胶质细胞进行免疫细胞化学标记。在胚胎第5天（E5）时，视网膜中没有QH1+巨噬细胞。从E7开始，来自栉膜的阿米巴样QH1+巨噬细胞进入视网膜。这些巨噬细胞通过在米勒细胞的终足上迁移，从视网膜中央向周边区域扩散，并在E12到达视网膜周边。当早期巨噬细胞沿着内界膜迁移时，其他巨噬细胞继续从栉膜进入视网膜直至孵化（E16）。从E9开始，随着发育的推进，巨噬细胞逐渐在视网膜巩膜层定居。巨噬细胞最早在E9出现在神经节细胞层，在E12出现在内网状层，在E14出现在外网状层。因此，似乎巨噬细胞首先沿着视网膜内表面切向迁移，然后从玻璃体向巩膜层迁移，以进入网状层，在那里它们分化为分支状小胶质细胞。巨噬细胞似乎在到达网状层后不久就开始分化，因为早在E12在内网状层和E14在外网状层就可以看到分支不良的QH1+细胞。巨噬细胞向外网状层的径向迁移一直持续到孵化后第3天，之后视网膜小胶质细胞呈现出成年分布模式。我们还观察到，在胚胎发育期间，当巨噬细胞迁移到视网膜时，大量玻璃体巨噬细胞紧密附着在栉膜表面。从孵化后开始就看不到这些玻璃体巨噬细胞了，此时没有更多的巨噬细胞进入视网膜。
