Ontogenetic development of diffusional restriction to protein at the pial surface of the rat brain: An electron microscopical study
Ontogenetic development of diffusional restriction to protein at the pial surface of the rat brain: An electron microscopical study
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DOI：
10.1023/a:1018527928760
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发表时间：
1997-03-01
期刊：
影响因子：
--
通讯作者：
Mollgard, K
中科院分区：
文献类型：
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作者：
Balslev, Y;Saunders, NR;Mollgard, K
血脑、血-CSF和脑室CSF-脑蛋白屏障在脑发育的早期就存在。为了确定大脑的外软膜表面是否也限制大分子的自由渗透，通过电子显微镜技术研究了胚胎第12天（E12）、第14天、第16天和第18天（出生当天（P0））的大鼠和成年大鼠的感觉运动皮层的背外侧部分。采用亚铁氰化钾、钌红和内源性白蛋白的免疫金标记来研究连接结构和白蛋白扩散限制位点。在E12，大开窗窦存在于软脑膜蛛网膜和脑表面形成的神经上皮和假定的放射状胶质终足的不完整层，但毛细血管在软脑膜蛛网膜显示没有开窗在E14或以后。从E14开始，我们观察到神经胶质端足之间的明显连接结构的逐渐出现，据我们所知，以前没有描述过。从E16到P0的白蛋白分布分析表明，连接可能有助于限制蛛网膜下腔和脑细胞外液之间的扩散。在软膜和室管膜表面对蛋白质渗透的限制可以确保在神经系统发育的关键阶段期间神经环境的隔离。在E12和P0之间的交界处的结构的变化表明一系列过渡的胚胎交界类型，最终让位于成熟的交界处的成人。胚胎神经胶质连接和成年无脊椎动物大脑中描述的连接之间的相似之处，表明在发育和个体发育中的连接发育中存在一些有趣的相似之处。
Blood-brain, blood-CSF and ventricular CSF-brain barriers to protein, are present very early in brain development. In order to determine whether the outer pial surface of the brain also restricts free penetration of macromolecules, the dorso-lateral part of the sensorimotor cortex from rats at embryonic day 12 (E12), 14, 16, and 18, the day of birth (P0), and adult rat, was studied by electron microscopical techniques. Potassium ferrocyanide, Ruthenium Red and immunogold labelling of endogenous albumin were used to investigate junctional structures and the sites of restriction to albumin diffusion. At E12, large fenestrated sinusoids were present in the pia-arachnoid and the brain surface was formed by an incomplete layer of neuroepithelial and presumptive radial glial end feet, but capillaries in the pia-arachnoid showed no fenestrations at E14 or later. From E14, we observed the progressive appearance of distinct junctional structures between the glial end feet which, to our knowledge, have not been described before. Analysis of albumin distribution from E16 to P0 suggests that the junctions may contribute to restriction of diffusion between the subarachnoid space and the brain extracellular fluid. The restriction to the penetration of protein at both the pial and the ependymal surfaces may ensure the isolation of the neural environment during a critical phase in development of the nervous system. The changes in the structure of the junctions between E12 and P0 suggests a transitional series of embryonic junctional types, which eventually give way to the mature junctions of the adult. Parallels between the embryonic glial junctions and junctions described in adult invertebrate brain, suggest some interesting parallels in junctional development in phylogeny and ontogeny.