Figure 29. . Development of the vertebrate eye cup.

Figure 29.

Development of the vertebrate eye cup. (a) The neural plate is the starting point for development of the neural tube. (b) The neural plate folds upwards and inwards. (c) The optic grooves form, and begin to evaginate. (d) The lips of the neural folds approach each other, and the optic vesicles bulge outwards. (e) After the lips have sealed, the neural tube is pinched off. At this stage the forebrain grows upwards and the optic vesicles continue to grow outwards. One aspect of this diagram that is not accurate is that the expanding optic vesicles actually have very little luminal/ventricular space; i.e. the wall thickness is much greater than shown here. (f) The expanding optic vesicles contact the surface ectoderm at the lens placode, inducing changes in both tissues. The optic vesicle now appears invaginated, and with the future retina closely apposed to the future RPE; what little ventricular space had been present between them disappears. Developing retinal ganglion cells send axons out across the retinal surface. The surface ectoderm at the lens placode thickens, forming the lens pit. The section in (f) is midline in the right eye, through the choroid fissure, so that only the upper region of retina/RPE is visible. (g) The eyecup continues to grow, through a combination of new material expanding outwards and continued warping of the eye cup. This expansion eventually causes the choroid fissure to seal over, thereby enclosing the axons of the optic nerve (as well as the hyaloid/retinal vessels; not shown). The ectodermal tissue continues to differentiate, eventually forming the lens. From Lamb et al (3). The text provides a link to an animation of this developmental progression.

From: Evolution of Phototransduction, Vertebrate Photoreceptors and Retina

Cover of Webvision
Webvision: The Organization of the Retina and Visual System [Internet].
Kolb H, Fernandez E, Nelson R, editors.
Salt Lake City (UT): University of Utah Health Sciences Center; 1995-.

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