Lecture 31: Eye Development Flashcards
Ectodermal placodes
Thickening in embryonic ectoderm constituting primordial group of cells from a sense organ
What is the primordium for Rathke’s pouch?
Hypophyseal placode
What is the primordium for olfactory epithelium?
Olfactory placodes
What is the primordium for the lens?
Lens placodes
What is the primordium for cranial nerve V?
Trigeminal placodes
What is the primordium for the inner ear?
Otic placodes
What is the primordium for sensory neurons supplying visceral structures?
Epibranchial placodes
How does BMP concentration affect formation of placodes?
Low BMP concentration in preplacodal region leads to formation of placodes
Neural crest derived cells constitute a significant component of which tissue of the eye?
A. Neural retina B. Lens C. Optic nerve D. Cornea E. None of the above
D. Cornea
What is the name of the groove that forms along the optic vesicle and is continuous with the optic stalk and posterior chamber of the eye?
Choroid fissue
What structure uses the choroid fissure and optic stalk to pass into the posterior chamber of the eye?
Hyaloid artery
Which gene is known as the “master gene for eye development”? Absence of this gene will lead to an eyeless mutant in Drosophila.
Pax6
How does absence of Pax6 affect mammals?
Early optic vesicle will form, but no other eye formation occurs - lens does not form
What is the effect of high [Shh] on Pax6?
Inhibits expression of Pax6
What is the effect of low [Shh] on Pax6?
In distal optic stalk, permits expression of Pax6 and development of optic vesicle, retina.
What are the effects of high [Shh] in the proximal optic stalk on Pax6 and Pax2?
Decreases expression of Pax6; Induces expression of Pax2
What is the function of Pax2?
Provides guidance of axons of ganglion cells of retina
What is the effect of downregulation of Pax6 by neural crest cells?
Prevents formation of prospective lens in surrounding areas
What are the effects of FGF, BMP, and Pax6 on the optic vesicle?
Induces formation of lens placode from lens ectoderm
What is the effect of Foxe3 on Lens vesicle?
Separation of lens vesicle from surface ectoderm
What effect does FGF have on vitreous humor?
Stimulates formation of lens fibers
What is responsible for the transformation of the overlying ectoderm from bi-layered epithelium to transparent multi-layered structure of the cornea?
Underlying lens vesicle
What is the role of TGF-B in maturation of the cornea?
Positive stimulation for migration between neural crest cells and ectoderm
What is the role of semaphorin 3A during maturation of the cornea?
Modulates TGFB production
What is the role of neurophilin-1 in maturation of the corena?
Inhibits migration of periocular neural crest cells
What is the role of hyaluronic acid in maturation of the cornea?
Secreted in primary stroma, causes swelling and enhances neural crest cell migration
What is responsible for differentiation of pigmented retina?
Oxt2 stimulated by Shh
Which axis of the retina is fixed first? What gradient is responsible for establishment of this axis?
Nasotemporal; ephrins, receptors
Expression of what gene prevents cells in the retina from differentiating too early?
Notch
Which axis of the retina is fixed second? What gradient establishes this axis?
Dorsoventral; Shh and BMP, with ventropin, Tbx-5, Pax2, Vax2
Anopthalmos
“Without eyes”
Micropthalmos
“Small eyes”
Coloboma
Failure of choroid fissure to close
