Table 231 Embryonic Origins of the Individual Structures of the

Source

Surface ectoderm Neural ectoderm

Mesoderm

Derivative

Lens

Epithelium of the cornea, conjunctiva, and lacrimal gland and its drainage system

Vitreous body (derived partly from neural ectoderm of the optic cup and partly from mesenchyme)

Epithelium of the retina, iris, and ciliary body

Sphincter pupillae and dilator pupillae muscles

Optic nerve

Sclera

Stroma of the cornea, ciliary body, iris, and choroid Extraocular muscles

Eyelids (except epithelium and conjunctiva)

Hyaloid system (most of which degenerates before birth)

Coverings of the optic nerve

Connective tissue and blood vessels of the eye, bony orbit, and vitreous body the sixth month as derivatives of the neuroectoderm of the outer layer of the optic cup.

The embryonic origins of the individual eye structures are summarized in Table 23.1.

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