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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.
The optic vesicles project toward the sides of the head, and the peripheral part of each expands to form a hollow bulb, while the proximal part remains narrow and constitutes the optic stalk. [1] [2] 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 ...
In embryology, the otic placode is a thickening of the ectoderm on the outer surface of a developing embryo from which the ear develops. The ear, including both the vestibular system and the auditory system, develops from the otic placode beginning the third week of development.
The lens placode under the direction of the optic vesicle gives rise to the lens of the eye. The adenohypophyseal placode , which forms the anterior lobe of the pituitary gland . Other animals
The cephalic end of the neural groove exhibits several dilatations, which, when the tube is closed, assume the form of three vesicles; these constitute the three primary cerebral vesicles and correspond respectively to the future fore-brain (prosencephalon), midbrain (mesencephalon), and hind-brain (rhombencephalon).
Invagination is the process of folding in cells. The lens placode invaginates to later develop the lens or lens pit. The development of the lens placode is typically seen between 44 and 50 hours; invagination occurs shortly after at around the 50–55-hour mark.
WASHINGTON (Reuters) -Donald Trump has tapped Keith Kellogg, a retired lieutenant general who presented him with a plan to end the war in Ukraine, to serve as a special envoy for the conflict, the ...
PAX6 is essential is the formation of the retina, lens and cornea due to its role in early cell determination when forming precursors of these structures such as the optic vesicle and overlying surface ectoderm. [20]