Flashcards in Embryology Deck (90)
what fibers are included in the fetal nucleus
contains all fibers before birth
what type of fibers are in the fetal nucleus
how does the embryonic nucleus form?
posterior epi elongates to fill the lumen
formation of the lens bow
what type of fibers are in the embryonic nucleus?
primary lens fibers
when do the eyelids fuse and separate?
fuse: month 3
separate: month 5-6
lacrimal system: surface ectoderm
nasolacrimal drainage system
what is a coloboma?
incomplete closure of fetal fissure in the inferior and nasal aspect
when does the optic cup elongates between the lens + cornea
what structures can be involved in an coloboma
optic disc, iris, retina, cb, optic nerve
what structures in the iris are formed from neural ectoderm
anterior + posterior iris epi
dilator + sphincter muscle
glial tissue persists at ONH
-posterior remnant on lens
-remnants of the fetal hyaloid system
-posterior remnant of the hyaloid system
what structure is the retina formed from?
small, circular opacity on the posterior lens capsule, classically nasal in location, which represents the anterior attachment of the hyaloid artery
what is the GCL + INL like at birth?
still thin layer across fovea
when are the GCL + INL completely displaced from fovea
4 months post birth
what is corneal curvature
-circular + steep (55D) @ birth
-decreases to 40D 6mo after birth
what is the first step in corneal development and when does it happen
day 33- corneal epi from surface ectoderm
absence of iris- altered depth of focus
iris: neural crest cells
when does myelination reach the chiasm? lamina cribosa?
chiasm: 6 mo
what is the horizontal raphe
wraps around mac bundles to get back to optic disc --> brain
-horizontal raphe is temporary
when does myelination reach lamina cribosa?
LC: 1-3 mo after birth
-visual implications, foveal displacement, cone development, myelination
where does myelination travel from and to
from brain --> eye
LGN --> lamina cribosa
horizontal raphe fibers
inferior and superior fibers dont cross
if damage to NFL - VD respects midline
inferior damage in horizontal raphe
where does maturation of PR occur
fovea + macula
what is in hollow eye ball
empty space filled w/ CSF
continuous w/ 3rd V
anterior border layer
how long can iris darken
6 mo after birth
bc --> blood to cornea