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Transverse section of head of chick embryo of forty-eight hours’ incubation Transverse section of head of chick embryo of fifty-two hours’ incubation, showing the lens and the optic cup. Eye formation in the human embryo begins at approximately three weeks into embryonic development and continues through the tenth week. [1]
The eyes begin to develop as a pair of diverticula (pouches) from the lateral aspects of the forebrain.These diverticula make their appearance before the closure of the anterior end of the neural tube; [1] [2] after the closure of the tube around the 4th week of development, they are known as the optic vesicles.
Pax6 is a transcription factor that is essential to the development of the lens placode. More specifically, it is needed for the surface ectoderm to fully develop. Pax6 has been identified as a necessary transcription factor for the thickness of the lens placode. [3] SOX2 is a transcription factor that works alongside Pax6 to develop the lens ...
During embryonic development of the eye, the outer wall of the bulb of the optic vesicles becomes thickened and invaginated, and the bulb is thus converted into a cup, the optic cup (or ophthalmic cup), consisting of two strata of cells.
Closure of the choroidal fissure in the optic stalk occurs during the seventh week of development. The former optic stalk is then called the optic nerve . [ 3 ] In short, the optic stalks are the structures that precede the optic nerves embryologically .
Newborn's eyes move in the same direction only about half of the time. [17] The strength of eye muscle control is positively correlated to achieve depth perception. Human eyes are formed in such a way that each eye reflects a stimulus at a slightly different angle thereby producing two images that are processed in the brain.
Their eyes transmit a message directly to the muscles without the intermediate processing provided by a brain. [21] During the Cambrian explosion, the development of the eye accelerated rapidly, with radical improvements in image-processing and detection of light direction. [30] The nautilus eye functions similarly to a pinhole camera.
Tension on the capsule is varied to allow the lens to subtly change shape to allow the eye to focus in a process called accommodation. Early in embryonic development the lens capsule is highly vascularized, but later during embryo development becomes avascular and transparent, serving as a diffusion barrier helping to protect the lens.