Development of eyes and ears

Development of Eyes

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

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)