Lens placode

The Lens placode is a thickened area of ectoderm that will give rise to the lens of the eye in vertebrate embryos. It is one of the earliest structures to form in the developing eye, and its formation is a crucial step in the overall process of eye development.

Etymology

The term "placode" comes from the Greek words "plax", meaning "plate", and "eidos", meaning "form". This refers to the plate-like shape of the placode in its early stages of development.

Development

The lens placode forms from the surface ectoderm in response to signals from the optic vesicle, a structure that itself forms from the diencephalon of the developing brain. The interaction between the optic vesicle and the overlying ectoderm is a key event in the induction of the lens placode.

As development progresses, the lens placode begins to invaginate, or fold in on itself, to form the lens pit. This invagination continues until the lens pit pinches off from the surface ectoderm to form the lens vesicle, the precursor to the mature lens.

Function

The lens placode is the embryonic structure that gives rise to the lens of the eye. The lens is a crucial component of the visual system, focusing light onto the retina to form clear images.

Related Terms

• Optic vesicle
• Surface ectoderm
• Lens pit
• Lens vesicle

See Also

• Eye development
• Embryology
• Ectoderm

• 
  Gray's Anatomy illustration of the lens placode