Fz4 and Fz5 are found in the distal area of the optic vesicle.

Both the optic vesicle and the head epidermis are required for eye development.

First, there is an outpocketing of the neural tube called optic vesicles.

Only the epidermis in the head is competent to respond to the signal from the optic vesicles.

The eye field gives rise to the optic vesicle and then to the optic cup.

The formation of the eyes starts as optic vesicles and lens derived from the neuroectoderm.

Expansion of the optic vesicles is obvious; they enlarge to hemispherical proportions.

Finally, the optic vesicle grows to form an optic outgrowth.

The optic vesicle induces nearby surface ectoderm to form the lens placode.

The optic vesicles come into contact with the surface ectoderm which thickens to form the lens placode.

This concentration gradient of BMP4 in optic vesicle is critical for lens induction.

Through a groove at the bottom of of the optic vesicle known as choroid fissure the blood vessels enter the eye.

The lens placode under the direction of the optic vesicle gives rise to the lens of the eye.

The competence of the head epidermis to respond to the optic vesicle signals comes from the expression of Pax6 in the epidermis.

The eye begins to develop as a pair of optic vesicles on each side of the forebrain at the end of the 4th week of pregnancy.

Optic vesicles are outgrowings of the brain which make contact with the surface ectoderm and this contact induces changes necessary for further development of the eye.

Invagination of the optic vesicle to form the optic cup occurs around E10, as the lens vesicle is developing [ 22].

The head end is markedly raised and appears knobby because of the swollen brain vesicles, the spherical optic vesicles, and the adhesive organs.

The prosencephalon further goes on to develop into the telencephalon (the forebrain or cerebrum) and the diencephalon (the optic vesicles and hypothalamus).

Development of the optic vesicles starts in the 3-week embryo, from a progressively deepening groove in the neural plate called the optic sulcus.

The gene engrailed is expressed first in the arms, funnel and optic vesicles, and is only later present in the tentacles and eyelids.

The optic disc originates from the optic cup when the optic vesicle invaginates and forms an embryonic fissure (or groove).

Into the optic vesicle and the developing eye and contributes to many anterior eye elements such the cornea, sclera, and ciliary muscle.

Failure of the cells of the posterior portion of the optic vesicles to express growth hormone affects the differentiation of other cells of the eye.

The first stage of lens differentiation takes place when the optic vesicle, which is formed from outpocketings in the neural ectoderm, comes in proximity to the surface ectoderm.