Human Embryo
EYE
Human Embryo
A7:
Mesencephalon. Rostral extensions of superior
cardinal vein
B1:
Developing diencephalon. Rathke's pouch. Lens pit
(derived from thickened ectoderm of lens or
"optic" placode).
B2,B3:
Optic cup with optic ventricle. Note unequal
thickness of walls of optic cup (inner wall;
sensory retina: outer wall; pigment epithelium).
Lens pit. Note position of eye with respect to
maxillary arch. Hyaloid vessels near ventral margin
of optic cup.
B4:
Junction of optic stalk to wall of prosencephalon
(diencephalon). Small branches of hyaloid blood
vessels in region between lens pit and optic
stalk.
B5:
Continuity of optic ventricle and single forebrain
ventricle via optic stalk. Note proximity of eye to
nasal placode (R).
B6: Hyaloid vessels ventral to optic stalk.
Optic mesenchyme (mesectoderm) arising directly
from epithelium of dorsal surface of optic cup.
Nasal placodes.
B7:
Tangential section through optic cup, with
surrounding optic mesenchyme. Nasal
placode Interorbital ligament. Bridge of
nose.
A6:Interorbital
ligament. Nose. uppereyelids. Cornea.
Anteriorchamber. Lens. Vitreous body. Sensory
retina. optic ventricle (artefact). Pigment
epithelium. Conjunctival
sac. Primordium of lacrimal glands (near lateral
fornix of conjunctival sac).
A7:
Medial rectus m. Primordium of nasolacrimal ducts.
Upper eyelid (lateral). Lower eyelid (medial).
B1:
Optic nerve. Note extensive temporal region of
retina. Primordium of nasolacrimal ducts.
B2:
Medial and lateral rectus m. Pigment epithelium.
Note relationship of eye to nasal capsule, sphenoid
cartilage and trigeminal ganglion. Primordium of
nasolacrimal ducts (cut obliquely).
B3:
On L, note course of maxillary division of
trigeminal in relation to position of eye (superior
to this level).
Human Embryo (selected sections)
A3,A4:
Optic ventricle (artefactually enlarged). Optic
nerve. Sensory retina. Pigment epithelium. Choroid
and sclera (not separable).
A5:
Sensory retina with optic nerve fibre layer and
young retinal ganglion cells. note radial
orientation of deeper retinal cells. Pigment
epithelium. Sclera plus choroid.
A6:
Anterior corneal epithelium and posterior corneal
endothelium. Corneal stroma. Angle of anterior
chamber with developing trabecular meshwork.
Anterior and posterior lens epithelium. Note change
in height of lens cells at the equator of the lens.
Double-layered epithelium of iris arising from rim
of optic cup. Stroma of iris lies anteriorly across
lens. Kink in internal wall of optic cup indicates
site where the ciliary body will form.
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