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Several layers such as the neural tube, neural crest, surface ectoderm, and mesoderm contribute to the development of the eye. [2] [3] [4] Eye development is initiated by the master control gene PAX6, a homeobox gene with known homologues in humans (aniridia), mice (small eye), and Drosophila (eyeless). The PAX6 gene locus is a transcription ...
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.
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.
Embryonic age: Week nr 5. 4 weeks old. 29–35 days from fertilization. The embryo measures 8 mm (0.31 in) in length and weighs about 1 gram. [4] Optic vesicles and optic cups form the start of the developing eye. Nasal pits form. The brain divides into 5 vesicles, including the early telencephalon. Leg buds form and hands form as flat paddles ...
Human embryonic development covers the first eight weeks of development, which have 23 stages, called Carnegie stages. At the beginning of the ninth week, the embryo is termed a fetus (spelled "foetus" in British English). In comparison to the embryo, the fetus has more recognizable external features and a more complete set of developing organs.
A key early discovery was of homeotic genes that regulate development in a wide range of eukaryotes. The field is composed of multiple core evolutionary concepts. One is deep homology , the finding that dissimilar organs such as the eyes of insects , vertebrates and cephalopod molluscs, long thought to have evolved separately, are controlled by ...
Changes in the eye can help predict other health concerns in the body, such as diabetes and high blood pressure. A new study has identified a set of 29 vascular health indicators on the retina ...
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.