The
eyes
An eye is a sensory organ that allows an organism to perceive visual information. It detects light and converts it into electro-chemical impulses in neurons (neurones). It is part of an organism's visual system.
In higher organisms, the ey ...
begin to
develop as a pair of
diverticula
In medicine or biology, a diverticulum is an outpouching of a hollow (or a fluid-filled) structure in the body. Depending upon which layers of the structure are involved, diverticula are described as being either true or false.
In medicine, t ...
(pouches) from the lateral aspects of the
forebrain
In the anatomy of the brain of vertebrates, the forebrain or prosencephalon is the rostral (forward-most) portion of the brain. The forebrain controls body temperature, reproductive functions, eating, sleeping, and the display of emotions.
Ve ...
. These diverticula make their appearance before the closure of the anterior end of the
neural tube
In the developing chordate (including vertebrates), the neural tube is the embryonic precursor to the central nervous system, which is made up of the brain and spinal cord. The neural groove gradually deepens as the neural folds become elevated, ...
; 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
The ectoderm is one of the three primary germ layers formed in early embryonic development. It is the outermost layer, and is superficial to the mesoderm (the middle layer) and endoderm (the innermost layer). It emerges and originates from the o ...
and extraocular
mesenchyme
Mesenchyme () is a type of loosely organized animal embryonic connective tissue of undifferentiated cells that give rise to most tissues, such as skin, blood, or bone. The interactions between mesenchyme and epithelium help to form nearly ever ...
– are necessary for normal eye growth and differentiation.
They 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, which goes on to form the
optic nerve
In neuroanatomy, the optic nerve, also known as the second cranial nerve, cranial nerve II, or simply CN II, is a paired cranial nerve that transmits visual system, visual information from the retina to the brain. In humans, the optic nerve i ...
.
Additional images
File:Gray460.png, Head of chick embryo of about thirty-eight hours’ incubation, viewed from the ventral surface. X 26
See also
*
Eye development
References
Citations
Sources
* Fuhrmann, S. (2010). Eye Morphogenesis and Patterning of the Optic Vesicle. Current Topics in Developmental Biology Invertebrate and Vertebrate Eye Development, 61–84. doi:10.1016/b978-0-12-385044-7.00003-5
External links
*
Overview at vision.ca
Embryology of nervous system
Human eye
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