To what extent are the retinal capillaries ensheathed by Muller cells?: A stereological study in the tree shrew Tupaia belangeri
To what extent are the retinal capillaries ensheathed by Muller cells?: A stereological study in the tree shrew Tupaia belangeri
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DOI：
10.1046/j.1469-7580.2000.19630453.x
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发表时间：
2000-04-01
影响因子：
2.4
通讯作者：
Knabe, W
中科院分区：
文献类型：
--
作者：
Ochs, M;Mayhew, TM;Knabe, W
用透射电镜对成年树鼩中央视网膜外3层毛细血管的细胞嵌套进行了定量研究。利用立体学方法，估计了5只动物毛细血管基底膜被穆勒细胞和非大胶质细胞（统称为非穆勒细胞）包裹的相对表面。Muller细胞在3个毛细管层中的参与程度有明显差异。在最外层的毛细层1中，非穆勒细胞过程的平均（标准差）表面覆盖率为46.8(15.3)%。毛细血管基底层2层和3层被非穆勒细胞包裹的细胞较少(分别为3.0（2.1)%和0.3(0.3)%）。观察到的穆勒细胞表面部分的体视学估计的总变异（用受试者间变异系数表示）在毛细管层1（28.8%）明显高于毛细管层2（2.2%）和3（0.3%）。在毛细层1中，观察到的高总变异是由于穆勒细胞和非穆勒细胞嵌套的组分在动物之间的高生物学变异。毛细血管基底层与小胶质细胞（毛细血管第3层）或无毛细胞（毛细血管第2层）的核周直接接触的情况很少，这与这些毛细血管层中被非穆勒细胞包裹的相对毛细血管表面获得的低立体学值很好地吻合。以前，在单个切片中观察到属于毛细血管1层的毛细血管基底层与水平细胞之间广泛而频繁的接触。本研究定量地证明了位于图帕亚毛细血管层1的毛细血管的大胶质投资明显缺乏。可见，水平细胞包住了大部分毛细血管表面，而不是穆勒细胞。
The cellular ensheathment of capillaries in the 3 outer capillary layers of the central retina of the adult tree shrew Tupaia belangeri was studied quantitatively by transmission electron microscopy. Using a stereological approach, the relative surface of capillary basal lamina ensheathed by Muller cells and by nonmacroglial cells (collectively termed non-Muller cells) was estimated in 5 animals. The participation of Muller cells was distinctly different in the 3 capillary layers studied. In the outermost capillary layer 1, the mean (standard deviation) percentage surface coverage by non-Muller cell processes was 46.8 (15.3)%. Much less of the capillary basal lamina was ensheathed by non-Muller cells in capillary layers 2 and 3 (3.0 (2.1)% and 0.3 (0.3)% respectively). The observed total variation of the stereological estimates for the surface fraction of Muller cells (expressed as the between-subject coefficient of variation) was significantly higher in capillary layer 1 (28.8%) compared with capillary layers 2 (2.2%) and 3 (0.3%). In capillary layer 1, the high observed total variation was due to a high biological variation among animals for the fractions of both Muller cell and non-Muller cell ensheathment. The rare occurrence of direct contacts between the capillary basal lamina and the perikarya of either microglial cells (capillary layer 3) or amacrine cells (capillary layer 2) corresponded well to the low stereological values obtained for the relative capillary surface ensheathed by non-Muller cells in these capillary layers. Previously, extensive and frequent contacts between the basal lamina of capillaries belonging to capillary layer 1 and horizontal cells had been observed in single sections. The present study quantitatively demonstrates a marked paucity of macroglial investment of capillaries located in capillary layer 1 of Tupaia. It can be concluded that horizontal cells ensheath most of the capillary surface not invested by Muller cells.