Paper - The process of retinal differentiation in man
Embryology - 28 Nov 2023    Expand to Translate
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Mann IC. The process of retinal differentiation in man. (1927) Proc R Soc Med. 21(1): 110.PubMed 19986142
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The Process of Retinal Differentiation in Man
Ida C. Mann, M.B., F.R.C.S. Eng.
The paper forms a demonstration, illustrated by numerous examples from the developing eyes of a series of human embryos, of the stages of rearrangement which can be seen during the formation of the retinal nuclear layers from the undifferentiated neuro-epithelium of the wall of the optic cup. The earliest stage dealt with is that of a 4-5 mm. human embryo which shows in the inner wall of the optic cup a division into marginal and nuclear layers only. After this stage the first of the definitive cells to become recognizable are the ganglion cells which develop by migration of the innermost cells of the nuclear layer into the marginal layer. Further increment of cells taking place from the outer to the inner layers, a distinct zone can soon be recognized which is known as the inner neuroblastic zone, the remains of the original nuclear zone being new distinguishable as the outer neuroblastic zone. From these two neuroblastic zones the layers of the definitive retina are developed. From the inner neurobla.stic zone are formed by differentiation the ganglion cells, the nuclei of the fibres of Müller and the amacrine cells. These latter are separated from the outer neuroblastic layer by a narrow interval (Wider in the area centralis), the transient fibre layer of Chiewitz.
From the outer neuroblastic layer are formed the bi-polar nuclei, the nuclei of the rods and cones and the horizontal cells. Towards the end of development the transient fibre layer disappears and in consequence the layer of amacrine cells and of nuclei of fibres of Müller fuses with the layer of bi-polar nuclei external to it to form the definitive inner nuclear layer. The internal molecular layer develops to separate this from the layer of ganglion cells. Later the external molecular layer develops and divides the original outer neuroblastic layer into two, namely an inner layer of bi-polar and horizontal cells and an outer layer of nuclei of rods and cones.
The definitive inner nuclear layer is therefore a. compound structure containing elements from both the original neuroblastic layers.
The following scheme shows the process divided into stages as it can be observed in the human embryo.
| First stage | Second stage | Third stage | Adult |
|---|---|---|---|
| Marginal layer | Superficial portion of marginal layer | Nerve fibre layer
Ganglion cells Inner molecular layer Inner nuclear layer Outer molecular layer Outer nuclear layer External limiting membrane | |
| Primitive neuroepithelium | Inner neuroblastic layer
Transient fibre layer of Chiewitz | ||
| Basement membrane | Inner neuroblastic layer |
fourth fo fiffh u-(mic si.rII1 week fo third month third to scrcntlz month Adult
Nerve fibre layer
Ganglion cells
Amacrine cells
M mlermn fibre -
nuclei
Bi-polar cells
Horizontal cells
Outer neuroblastic layer
Nuclei of rods and cones
Primitive rods and cones. Rods and cones
Cite this page: Hill, M.A. (2023, November 28) Embryology Paper - The process of retinal differentiation in man. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Paper_-_The_process_of_retinal_differentiation_in_man
- © Dr Mark Hill 2023, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G
