Which process forms the lens vesicle during lens development?

• A. Evagination of the optic vesicle
• B. Differentiation of corneal epithelium
• C. Invagination of lens placode to form lens vesicle
• D. Migration of neural crest cells

Answer: (C)

During lens development, the key event is the invagination of the lens placode. The placode is a thickened patch of surface ectoderm that forms under the influence of signals from the underlying optic vesicle. When it folds inward, it becomes a hollow lens vesicle that separates from the surface ectoderm. This inward folding is what creates the lens structure and sets up the layers that will differentiate into the anterior lens epithelium and the posterior lens fibers. Other processes relate to other eye tissues: corneal epithelium differentiates from surface ectoderm, neural crest cells contribute to the corneal stroma and other ocular structures, and evagination of the optic vesicle forms retinal components rather than the lens vesicle.