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The eyes sit in bony cavities called the orbits, in the skull. There are six extraocular muscles that control eye movements. The front visible part of the eye is made up of the whitish sclera, a coloured iris, and the pupil. A thin layer called the conjunctiva sits on top of this. The front part is also called the anterior segment of the eye.
The retina (from Latin rete 'net'; pl. retinae or retinas) is the innermost, light-sensitive layer of tissue of the eye of most vertebrates and some molluscs.The optics of the eye create a focused two-dimensional image of the visual world on the retina, which then processes that image within the retina and sends nerve impulses along the optic nerve to the visual cortex to create visual perception.
The inner plexiform layer is an area of the retina that is made up of a dense reticulum of fibrils formed by interlaced dendrites of retinal ganglion cells and cells of the inner nuclear layer. Within this reticulum a few branched spongioblasts are sometimes embedded.
In the anatomy of the eye, the inner nuclear layer or layer of inner granules, of the retina, is made up of a number of closely packed cells, ...
The sclera's blood vessels are mainly on the surface. Along with the vessels of the conjunctiva (which is a thin layer covering the sclera), those in the episclera render the inflamed eye bright red. [6] In many vertebrates, the sclera is reinforced with plates of cartilage or bone, together forming a circular structure called the sclerotic ring.
So-called under-focused lens eyes, found in gastropods and polychaete worms, have eyes that are intermediate between lens-less cup eyes and real camera eyes. Also box jellyfish have eyes with a spherical lens, cornea and retina, but the vision is blurry.
The internal limiting membrane, or inner limiting membrane, is the boundary between the retina and the vitreous body, formed by astrocytes and the end feet of Müller cells. It is separated from the vitreous body by a basal lamina.
The inner layer of the optic cup is made of neuroepithelium (neural retina), while the outer layer is composed of retinal pigment epithelium (RPE). Experiments have determined that RPE cell differentiation and maintenance requires interaction with neighboring tissues, most likely canonical Wnt signaling, while neural retina differentiation is ...