SDL Development of Eye & Ear Flashcards
how does the optic vesicle differ from the lens placode with respect to its development? which one is derived from an outpocketing of neuroectoderm?
optic vesicle induces overlying ectoderm to differentiate into the lens
lens placode induces the differentiation of the neural retina (outpocketing of ectoderm)
how is the embryonic intraretinal space formed? what happens to this space?
formed from continued growth of the optic vesicle
the intraretinal space disappears as the two layers oppose each other
how is the embryonic intraretinal space related to an injury-induced detached retina in an adult?
a retinal detachment is a re-opening of the intraretinal space - sxs: sudden floaters, flashing lights, black curtain
what is the choroid fissure? what travels through it?
choroid fissure is an invagination of optic vesicle; the hyaloid artery passes through it
what happens to the choroid fissure during development? persistence of the choroid fissure results in what developmental defect?
the choroid fissure eventually fuses; failure to close results in coloboma iridis
what is unique about the smooth muscles of the pupil as regards to their developmental origin?
the smooth muscles are unique in that they are derived from neuroectoderm of the optic cup
how does the sclera and choroid form? which is continuous with dura mater?
sclera formed from an outer layer of eye promordium surrounded by mesenchyme- continuous with dura mater/cornea
the choroid formed from inner vascular pigmented layer- continuous with pia and iris
the iridopupillary membrane is derived from which germ layer? what happens to this membrane?
mesoderm
later disappears
what defect occurs if the iridopupillary membrane persists in the adult?
there’s an iridopupillary membrane covering the pupil
what is coloboma iridis?
opening of pupil due to failure to close the choroid fissure
what is aniridia?
absence of the iris
what is aphakia?
absence of the lens
how do the otic vesicles form? what germ layer are they from?
invagination of the otic placodes forms the otic pits which then separate from the surface ectoderm*
which parts of the otic vesicle give rise to the semicircular canals? which parts give rise to the cochlear ducts?
dorsal component forms semicircular canals
ventral component forms cochlear duct
are semicircular canals/cochlear duct ectodermal, endodermal or mesodermal in origin?
ectodermal
