70 Eye development

Question 1

Eyes begin to develop in ______ day embryos when _________ appear.

Answer 1

22;

optic grooves

Question 2

Eyes are derived from which 4 sources?

Answer 2

1. Neuroectoderm > refina, posterior layers of iris, optic nerve
2. Surface ectoderm > lens of eyes, anterior corneal epithelium
3. Mesoderm: between neuroectoderm and surface ectoderm > fibrous and vascular coats of eye
4. Neural crest cells: migrate to mesenchyme > choroid, sclera, corneal endothelium

Question 3

Early development of the human eye.

Answer 3

1. 22 day: optic groove bulge out from the lateral walls of the forebrain
2. Optic grooves evaginate from future diencephalon to form hollow diverticula called optical vesicles.
3. As optic vesicle grow, their distal ends expand > constrict to form hollow optic stalk. Surface ectoderm adjacent to vesicle thickens to form lens placode.
4. Lens placode invaginate to form lens pit.