Development of Eyes

(I) Retina and optic nerve

• Optic vesicle of prosencephalon extends laterally
• Contacts surface ectoderm
• Optic vesicle invaginated to form optic cup:

1. Outer layer – forms pigmented layer of retina
2. Inner layer anterior 1/5 – iris and ciliary body
3. Inner layer posterior 4/5 – All layers of retina except pigmented layer

• Mouth of optic cup forms pupil
• Optic stalk invaginated by central artery of retina – gets enclosed in optic stalk – forms optic nerve

(II) Lens

• Surface ectoderm thickens – forms lens placode
• Lens placode invaginated at optic cup mouth – forms lens vesicle
• Lens vesicle separates from surface ectoderm
• Lies in optic cup mouth
• Cells of posterior layer of lens vesicle elongate – forms lens fibers

(III) Choroid and sclera – Forms from mesenchyme around optic vesicle

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Development of Ear

Develops from pharyngeal arches (link)

Develops around 4th and 5th week of development, while the middle ear ossicles form around 6 weeks of development.

Muscles of middle ear – tensor tympani (1st arch) and stapedius muscle (2nd arch)