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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. Previous studies of optic vesicles suggest that the surrounding extraocular tissues – the surface ectoderm and extraocular mesenchyme ...
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 ...
[3] [4] Optic cup morphogenesis is the invagination process occurring after neuroectoderm movement forms the spherical optic vesicle (Phase 1). Invagination is when a tissue folds back on itself. Over the course of approximately 12 hours, the distal end of the optic vesicle inner layer begins to flatten (Phase 2).
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
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.
One example of an intrinsic regulator of this process is the transcription factor Ath5. Ath5 expression in retinal progenitor cells biases their differentiation into a retinal ganglion cell fate. [1] An example of an environmental factor is the morphogen sonic hedge hog . Shh has been shown to repress the differentiation of precursor cells into ...
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.
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]