Embryology of the Eye Flashcards
what two tissues form the eye
ectoderm (neural and surface) and mesenchyme
what is responsible for the development of many ocular structures
induction
what are the 3 germ layers in development
ectoderm (outer), mesoderm (middle), and endoderm (inner)
what do the 3 germ layers form
the embryonic plate
what is the neural groove
a longitudinal groove that forms down the neural plate, where the neural folds form from
what does the neural plate give rise to
the central nervous system and eye
what is the neural tube made of
neural ectoderm
what surrounds the neural ectoderm
mesoderm (covered by neural ectoderm on the dorsal side)
what are the 2 kinds of ectoderm
neural and surface
what are the neural crest cells
when the neural folds are moving towards another to fuse, these cells form and become specialized between the neural tube and surface ectoderm (in the mesoderm)
what is mesenchyme
includes mesoderm and neural crest cells
what are the optic pits
small depressions that form as the neural tube is closing
what are the optic vesicles
when the optic pits begin to form outer pits that extend from the lateral aspect of the forebrain
what is the optic stalk
the proximal portion of each optic vesicle near the forebrain begins to constrict and form the optic stalk
what is continuous with the 3rd ventricle of the brain
a cavity inside the optic vesicle and optic stalk
what is the inferior optic fissure
the opening of the optic stalk that allows the Hyaloid vasculature to enter the stalk, it will then close after
what is the inferior optic fissure called after it closes
optic canal
what structures come from the optic cup inner layer
neural retina, non-pigmented ciliary epithelium, iris posterior pigmented epithelium
what structures come from the optic cup outer layer
RPE, pigmented ciliary epithelium, iris anterior pigmented epithelium
what is induction
the influence a structure has on another structure
what is the lens plate or lens placode
when the optic vesicle was in contact with the surface ectoderm, the surface ectoderm thickens to form it
what does the lens plate form
it elongates and invaginates to for the lens pit and then closes to form the lens vesicle
what happens to the lens vesicle to form the embryologic nucleus
the posterior epithelial cells elongate anteriorly to fill the cavity and are now referred to as primary lens fibers
what form the lens bow
the primary epithelial cells move anteriorly and form a bow (no sutures yet)
what do the first set of secondary lens fibers form
they surround the embryonic nucleus and meet as anterior upright Y sutures and posterior inverted Y sutures
what will remain if the hyaloid vasculature does not fully resorb by birth
Bergmeisters papilla and Mittendorf’s dot
what does the Hyaloid vasculature give rise to
the central retinal artery and vein
what does the developing RPE induce to form
choriocapillaries from the mesenchyme
which layer pigmented or nonpigmented ciliary epithelium forms the ciliary processes
the pigmented form the processes and the NPE follow
when is aqueous humor produced
around 4-6 months of gestation
where is the ciliary body stroma made from
neural crest cells
where is the ciliary muscle derived from
mesenchyme
where does the iris come from
the rim of the optic cup, between the lens and cornea
where are the iris sphincter and dilator from
neural ectoderm (only muscles that are)
what is the iris stroma formed from
mesenchyme
where does the pupillary membrane form
between the lens epithelium and the corneal endothelium
what is the pupillary membrane made from
transient structure from mesenchyme, resorbed by birth
how do the anterior and posterior chambers form
they develop as slits and eventually communicate when the pupillary membrane disappears
what is trabecular meshwork derived from
mesenchyme
what is schlemms canal derived from
deep scleral plexus
what does the fibrilar material secreted by embryonic retina and ectodermal cells of the lens form
the primary vitreous
when does the secondary vitreous form
as the optic cup continues to increase in size
where does the secondary vitreous come from
neural retina and degenerating hyaloid vasculature
what is the first layer of the retina to form
the RPE
what is the retina formed from
the inner layer of the optic cup
what area of the retina is the first to form
the macular area, the thickest area for awhile
what is the last portion of the retina to fuly develop
the foveola
what induces the formation of the cornea
the lens vesicle
what is the corneal epithelium derived from
surface ectoderm
what is the corneal endothelium derived from
neural crest cells
what is the corneal stroma derived from
mesenchyme
what is the sclera derived from
condensations of mesenchyme outside the optic cup
how do the eyelids develop
as folds (epithelial buds) of surface ectoderm, filled with mesenchyme
are the eyelids fused together until they are fully developed
yes
