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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).
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.
The neural groove is a shallow median groove of the neural plate between the neural folds of an embryo.The neural plate is a thick sheet of ectoderm surrounded on either side by the neural folds, two longitudinal ridges in front of the primitive streak of the developing embryo.
Human eye cross-sectional view grayscale. Retinal precursor cells are biological cells that differentiate into the various cell types of the retina during development. In the vertebrate, these retinal cells differentiate into seven cell types, including retinal ganglion cells, amacrine cells, bipolar cells, horizontal cells, rod photoreceptors, cone photoreceptors, and Müller glia cells. [1]
This process is known as neurulation. [8] When the tube is closed at both ends it is filled with embryonic cerebrospinal fluid. [9] As the embryo develops, the anterior part of the neural tube expands and forms three primary brain vesicles, which become the forebrain (prosencephalon), midbrain (mesencephalon), and hindbrain (rhombencephalon).
The neural fold is a structure that arises during neurulation in the embryonic development of both birds and mammals among other organisms. [1] [2] This structure is associated with primary neurulation, meaning that it forms by the coming together of tissue layers, rather than a clustering, and subsequent hollowing out, of individual cells (known as secondary neurulation).