A BURST OF DIFFERENTIATION IN THE OUTER POSTERIOR RETINA OF THE 11-WEEK HUMAN FETUS - AN ULTRASTRUCTURAL-STUDY
A BURST OF DIFFERENTIATION IN THE OUTER POSTERIOR RETINA OF THE 11-WEEK HUMAN FETUS - AN ULTRASTRUCTURAL-STUDY
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DOI：
10.1017/s0952523800000067
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发表时间：
1990-07-01
影响因子：
1.9
通讯作者：
FISHER, SK
中科院分区：
文献类型：
--
作者：
LINBERG, KA;FISHER, SK
许多关于人类视网膜发育的研究指出，妊娠第三个月是视网膜后部经历快速分化和成熟的时期，包括视锥前体的排列。第三个月视网膜后部的超微结构数据非常有限，完全缺乏视锥细胞单层。我们检查了两个孕周在10周到11周之间的人胎视网膜。在视锥细胞单层出现之前，外层的神经视网膜由同质的未分化的神经母细胞组成。有丝分裂的迹象仍然很明显，甚至在后方。没有外丛状层(OPL)。神经性视网膜与视网膜色素上皮(RPE)的界面在很大程度上是无特征的。到11周时，视网膜后部有一层薄的OPL，它将发育中的内核层中的多排细胞与单层黄斑锥体前体细胞分开。RPE单层由立方体细胞组成，其顶端表面有突起的细胞质和分支突起，突起投射到视网膜下间隙。这些大的立方体锥体彼此相连，在外界膜上连接着米勒细胞。它们显示出脊椎动物光感受器典型的结构极性的明确迹象。其顶端细胞质含有许多内节共有的细胞器，而基底部的细胞质有突触带和小泡，并接受来自OPL神经束中的突起的内陷接触，这些突起是由分化的二级神经元产生的。侧面的锥体表面被巨大的地下水池相互覆盖。
Many studies on human retinal development have cited the third gestational month as a period when the posterior retina undergoes rapid differentiation and maturation, including a lining up of cone precursors. Ultrastructural data on the posterior retina during the third month are very limited, and totally lacking for the cone monolayer. We have examined two human fetal retinas between ten and 11 gestational weeks. Before the appearance of the cone monolayer, the outer neural retina consists of a homogeneous population of undifferentiated neuroblasts. Mitotic figures are still evident, even posteriorally. There is no outer plexiform layer (OPL). The interface of neural retina to retinal pigment epithelium (RPE) is largely featureless. By 11 weeks, the posterior retina has a thin OPL that separates the many rows of cells in the developing inner nuclear layer from the single tier of macular cone precursors. The RPE monolayer consists of cuboidal cells whose apical surface elaborates ridges of cytoplasm and branched processes that project into the subretinal space. The large, cuboidal cones are linked to each other and Müller cells at the outer limiting membrane. They show definitive signs of the structural polarity typical of vertebrate photoreceptors. Their apical cytoplasm contains many organelles common to the inner segment, while the basal cytoplasm has synaptic ribbons and vesicles, and receives invaginating contacts from processes in the OPL neuropil arising from differentiating second-order neurons. Lateral cone surfaces are mutually underlain by large subsurface cisterns.