人视网膜星形胶质细胞发育及起源的研究

背景 视网膜星形胶质细胞是视网膜主要的神经胶质细胞,其起源及演变过程一直是国内外研究的热点和难点. 目的 探讨人胚胎眼视网膜星形胶质细胞的起源及发育.方法 收集33例自愿终止妊娠的流产人胚胎眼标本,其中8 ～12孕周者20例,15～ 17孕周者2例,19～ 23孕周者4例,25～ 28孕周者4例,30 ～32孕周者3例.对眼球壁切片进行常规组织病理学检查以观察不同胚龄人视网膜发育的形态学变化,分别采用免疫组织化学法及免疫荧光法动态观察不同胚龄人视网膜星形胶质细胞起源位点及发育过程中胶质纤维酸性蛋白( GFAP)表达的变化.结果 人胚6～7周视杯处于视网膜分层发育阶段,9周时视杯内层原无细胞层出现分化不成熟的圆短梭形细胞；胚龄15周时视网膜主要层次可见,分化的细胞增加,但未发现GFAP阳性细胞；胚龄19周视网膜可见梭形细胞从返折部原始神经上皮迁出,并可见这些细胞中GFAP呈阳性表达；胚龄25～ 26周后极部视网膜可见GFAP表达阳性的梭形细胞,这些细胞围绕视网膜血管分布,与血管壁联系密切,邻近锯齿缘处的视网膜内层可见表达GFAP的星形或梭形细胞与睫状体非色素上皮相连,但锯齿缘稍后与赤道区之间并未见GFAP阳性细胞；胚龄28周,视网膜星形胶质细胞呈典型的星状,其突起伸达视网膜内网状层. 结论 人视网膜星形胶质细胞至少存在3个起源位点,即血管前体细胞/周皮细胞、视盘旁原始神经上皮及邻近锯齿缘的睫状体无色素上皮.

Origin and development of human retinal astrocyte

Background Retinal astrocytes are the main glial cells of retina, their origin and evolution progress are always the hot and difficult points in domestic and foreign researches. Objective This study was to explore the origin and development of retinal astrocytes in human fetal retina. Methods Thirty-three human embryonic eyes were collected from the abortion with the embryonic ages of 8-12 gestation weeks （20 eyes） , 15-17 gestation weeks （2 eyes）, 19-23 gestation weeks （ 4 eyes ）, 25 -28 gestation weeks （4 eyes ）, 30- 32 gestation weeks （3 eyes）. The section of eyeball wall was prepared to observe the morphology and structure of different embryonic ages of retinas by regular histopathology examination. The origin of human embryonic retinal astrocytes was assessed by evaluating the change of GFAP expression in different embryonic ages of retinas using immunochemistry and immunofluorescence under the light and laser scanning confocal microscope. Theresearch was approved by the the Ethics Committee. Results The optic cup in embryonic 6- 7 weeks was in the retinal layering phase. Some immature short or round spindle-like cells appeared in primitive non-cell layer in the inner layer of the optic cup in embryonic 9 weeks of eyes. There were no positive GFAP-immunoactive cell was detected until embryonic 15 weeks of eyes. Some spindle-like cells migrated from a single layer primitive neuroepithelium next to optic disc expressing GFAP in the eyes with embryonic 19 weeks, and positive immunostaing for GFAP were detected in stellate cells surround blood vessels, and some seem to form the vessel wall in the ganglion cell layer and nerve fiber layer of the fetal central retina from 25 weeks through 26 weeks. Some positive response cells for GFAP presented in inner layer of the retina closed to ora serrata with the connection to nonpigmented epithelium （NPE） of the ciliary body during this period. Human retinal astrocytes showed typical stellate-like in shape, and the cellular processes crossed into inner plexiform layer in embryonic 28-week eyes. Conclusions Human retinal astrocytes mainly seem to have three kinds of origin in human embryonic eyes, and they are vascular precursor cell/pericytes, primitive neuroepithelium and nonpigmented epithelium of the ciliary body.