本文就視網膜橫斷面(in cross-section)和正面(en face)形態結構進行解述，文末附有關鍵詞的中文釋義
The innermost and highly developed layer of the eyeball is known as retina. In fact, the retina is a part of the brain and develops from the optic vesicle, an outgrowth from the forebrain. The outer wall of the vesicle forms the retinal pigment epithelium and the inner, the neurosensory retina.
The retina, a thin transparent membrane, lies between the choroid and the hyaloid membrane of vitreous. It extends from the optic disk to the anterior end of the choroid where it has a serrated termination known as ora serrata. More anteriorly, it is continuous with the epithelium of the ciliary body.
Recent advances in optics using adaptive optics, interference, and tomography to create high-resolution images through the multiple layers of the retina (~250 μm thick). These technical breakthroughs advance our abilities to image the retina with high resolution. This noninvasive imaging can be repeated with excellent alignment using key anatomical landmarks, making it possible to follow specific features of any retina over a time. The time series of images is particularly useful in monitoring disease progression and the effects of surgical intervention or treatment efficacy.
Historic studies by Ramony Cajal discovered the connections among specific cell types of the retina that led to the neuron doctrine. He was able to resolve and identify RPE, photoreceptor cells, horizontal cells, bipolar cells, amacrine cells, ganglion cells, and müller cells in the retina. He classified many subtypes of each cell and identified the major circuitry of one cell to the next in the retina.
The retina comprises photoreceptor cells, a relay layer of bipolar cells and ganglion cells and their axons that run into the central nervous system. Microscopically, the retina from without inwards is made up of following ten layers:
1. Retinal pigment epithelium
2. Photoreceptor layer
3. External limiting membrane
4. Outer nuclear layer
5. Outer plexiform layer
6. Inner nuclear layer
7. Inner plexiform layer
8. Ganglion cell layer
9. Nerve fiber layer
10. Inner limiting membrane
When the retina is viewed en face, the retina typically exhibits a regular pattern of nuclear spacing of cells of the same type often referred to as homotypic interactions, exclusion zones. Cell soma and nuclei of one subtype of cells are spaced about the same distance apart from one neighbor to each of its immediately adjacent neighbors. Homotypic cell types in many inner retina cells exist a regular spacing of cell bodies.
The dendrites of one cell may block the intrusion of dendrites from another cell, other cell types exhibit regular spacing of cell bodies yet have large overlaps of dendrites over long ranges. Finally, a uniform cell cross-sectional area and high-density packing can generate cell mosaics by the physics of packing (this occurs in the foveola with cone outer segments).
Retinal mosaics are commonly associated with the phenomenon of dendritic tiling, by which each cell in a mosaic extends its dendritic processes to 「tessellate」 the retinal surface by limiting further growth at the boundaries with homotypic dendritic fields.
optic vesicle 視泡
ora serrata 鋸齒緣
alignment 校準
anatomical landmarks 解剖標誌
neuron doctrine 神經元學說
amacrine cells 無長突細胞
ganglion cells 神經節細胞
axons 軸突
homotypic interactions 同型相互作用
soma and nuclei 胞體和胞核
dendrites 樹突
spacing 間距
mosaics 馬賽克
tessellate 鑲嵌
RPE, Retinal pigment epithelium 視網膜色素上皮
PL, Photoreceptor layer 光感受器細胞層
ELM, External limiting membrane 外界膜
ONL, Outer nuclear layer 外核層
OPL, Outer plexiform layer 外叢狀層
INL, Inner nuclear layer 內核層
IPL, Inner plexiform layer 內叢狀層
GCL, Ganglion cell layer 神經節細胞層
NFL, Nerve fiber layer 神經纖維層
ILM, Inner limiting membrane 內界膜
DOI: 10.1016/bs.pmbts.2015.06.001
Ophthalmology