The following data is from a study of human embryonic carnegie stages[5] and other sources.
- Stage 10 - optic primordia appear.
- Stage 11 - right and left optic primordia meet at the optic chiasma forming a U-shaped rim.
- Stage 12 - optic neural crest reaches its maximum extent and the optic vesicle becomes covered by a complete sheath,
- Stage 13 - By the end of the fourth week the optic vesicle lies close to the surface ectoderm. Optic evagination differentiation allows identification of optic part of retina, future pigmented layer of retina, and optic stalk. The surface ectoderm overlying the optic vesicle, in response to this contact, has thickened to form the lense placode.
- Stage 14 - (about 32 days) the lens placode is indented by the lens pit, cup-shaped and still communicates with the surface by a narrowing pore.
- Stage 15 - (about 33 days) the lens pit is closed. The lens vesicle and optic cup lie close to the surface ectoderm and appear to press against the surface.
- Stage 16 - (37 days) Growth of the lens body results in a D-shaped lens cavity. Perilental blood vessels (tunica vasculosa lentis) are visible. Prior to the development of the eyelids, one small sulcus or groove forms above the eye (eyelid groove) and another below it.
- Stages 17 - 19 - Retinal pigment is visible and the retinal fissure is largely closed. Eyelids grooves deepen, eyelid folds develop, first below, and then above, the eye.
- Stages 18 - Mesenchyme invades the region between the lens epithelium and the surface ectoderm.
- Stages 19 - 22 - the eyelid folds develop into the eyelids and cover more of the eye as the palpebral fissure takes shape. The upper and the lower eyelids meet at the outer canthus in Stage 19.
- Stage 20 - The lens cavity is lost and a lens suture begins to form. The inner canthus is established.
- Stage 23 - The retina comprises the pigmented layer, external limiting membrane, proliferative zone, external neuroblastic layer, transient fiber layer, internal neuroblastic layer, nerve fiber layer, and internal limiting membrane. Eyelids closure is complete (Note - shown as still open in the Kyoto embryo).
Lens
The lens or crystalline lens or aquula (Latin, aquula = a little stream) has a key role in focussing light (with the cornea) upon the neural retina. The lens embryonic origin is from surface ectoderm of the sensory placodes that form in the head region (More? Week 4 - Placodes). The lens focusses by refracting light as it passes through the biconvex lens, which can be altered in shape (accommodation) by surrounding ciliary muscles. These ciliary muscles are activated (contracted) by parasympathetic innervation from the ciliary ganglion itself innervated by the oculomotor nerve (Cranial Nerve III) (More? Cranial Nerves).
surface ectoderm -> lens placode -> lens pit -> lens vesicle -> lens fibres -> lens capsule and embryonic/fetal nucleus.
- Links: Vision - Lens Development
Retinotopic Map
This neuroscience term describes how the developing retina is precisely "mapped" onto the visual cortex through a series of signaling and activity dependent mechanisms. This follows from Hubel and Wiesel (1981 Nobel Prize in Physiology or Medicine) key discoveries (1959-70) of how in development system matching occurs in the visual system. The topographic map establishes an ordered neuronal connection between sensory structures and the central nervous system.
The retinotectal map (eye to brain) of birds (lower vertebrates):
- temporal (posterior) retina is connected to the rostral (anterior) part of the contralateral optic tectum
- nasal (anterior) retina to the caudal (posterior) tectum
- ventral retina to the dorsal (medial) tectum
- dorsal ventral (lateral) tectum
Retinal waves a form of coordinated spontaneous activity that occurs in the developing retina. These waves of electrical activity (action potentials) are thought to have a role in establishing the initial retinotopic map by correlating/coordinating the activity of neighbouring retinal ganglion cells.
EphA/ephrin-A molecular signaling also thought to have a role in establishing the initial retinotopic map.
Neural Crest
Mouse eye neural crest[6]
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Mouse eye TGF-beta model[6]
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- Links: Image - Mouse eye neural crest | Image - Mouse eye TGF-beta model | Vision Development | Neural Crest Development | Head Development
Extraocular muscles are required to move the eye within the orbit. Their embryonic origin requires an interaction between the cranial mesoderm and the migrating neural crest cells.
The following is from a recent paper comparing human to zebrafish muscle development.[7]
About the Muscles
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Legend
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- Five of the six muscles (inferior rectus, superior rectus, lateral rectus, medial rectus, and superior oblique) originate at a common tendinous ring of fibrous tissue (the Annulus of Zinn).
- The Annulus of Zinn surrounds the optic nerve, ophthalmic artery, and ophthalmic vein at their entrance through the apex of the orbit.
- The sixth muscle (inferior oblique) has a separate origin point on the orbital side of the bony maxilla at the anterior inferomedial strut.
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- IR - inferior rectus
- SR - superior rectus
- LR - lateral rectus
- MR - medial rectus
- SO - superior oblique
- IO - inferior oblique
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Additional Images
Human stage 22 developing iris region
Human stage 22 developing iris region
Human stage 22 overview of optic nerve
Human stage 22 overview of eye
Human stage 22 lens and hyaloid vessels
Human stage 22 optic nerve (stalk)
Mouse adult optic nerve axons
Historic Images
Fig. 456. Location of optic areas before the closure of the neural groove.
Fig. 457. Location of areas shown in Fig. 456 after the formation of the neural canal.
Fig. 458. Location of the optic area after the beginning of the formation of the optic cup and optic stalk. Fig. 459. Dorsal view of head of chick of 58 hours' incubation.
Fig. 460. Section through head of chick of two days' incubation.
Fig. 461. Section through head of chick of three days' incubation.
Fig. 462. Later stage in development of optic cup and lens than is shown in Fig. 461.
Fig. 463. Developing lens and optic cup.
Fig. 464. Model showing lens and formation of optic cup.
Fig. 465. Stages in the development of the lens in the rabbit embryo.
Fig. 466. Section through optic cup and lens invagination of chick of fifty-four hours' incubation.
Fig. 467. Section through eye of human embryo of 13-14 weeks.
Fig. 468. Development of the retinal cells.
Fig. 469. Vertical section through retina of a four months' human embryo.
Fig. 470. Vertical section through retina of a five and one-half months' human embryo.
Fig. 1. Section through head of pig, 2 mm long.
Fig. 2. Section through head of chick, 2 mm long.
Fig. 3. Section through head of Foetal Pig, 2 mm long.
Fig. 4. Section through head of Foetal Pig, 3 mm long.
Fig. 5. Section through head of Foetal Pig, 3 mm long.
Fig. 6. Section through head of Foetal Pig, 4 mm long.
Fig. 7. Section through head of Foetal Pig, 7 mm long.
Fig. 8. Section through head of pig, 8 mm long.
Fig. 9. Section through head of pig, 9 mm long.
Fig. 11. colobomba of the fundus in the adult and means a lack of development.
References
- ↑ <pubmed>12186651</pubmed>| Genome Biol.
- ↑ <pubmed>22496813</pubmed>
- ↑ <pubmed>20544023</pubmed>| PLoS ONE
- ↑ <pubmed>20459797</pubmed>
- ↑ <pubmed>7364662</pubmed>
- ↑ 6.0 6.1 <pubmed>16403239</pubmed>| J Biol.
- ↑ <pubmed>22132088</pubmed>| PLoS One.
Online Textbooks
Reviews
<pubmed>20855501</pubmed>| JCB
The International Journal of Developmental Biology Vol. 48 Nos. 8/9 (2004) Eye Development
Articles
<pubmed>19541779</pubmed>
Bookshelf vision development
Search Pubmed
Search Pubmed: vision development | eye development | eye embryology | retina embryology | lens embryology
Search Entrez: vision development | eye development | eye embryology | retina embryology | lens embryology
Terms
- retina - The stratified sensory structure of the eye, formed from the neural ectoderm that extends from the forebrain (diencephalon) to form initially the folded optic cup. Vertebrates have ten identifiable layers formed from nerve fibers, neurons, membranes, photoreceptors and pigmented cells. Light must pass through nearly all these layers to the photoreceptors. (1. Inner limiting membrane - Müller cell footplates; 2. Nerve fiber layer; 3. Ganglion cell layer - layer of retinal ganglion cells their axons form the nerve fiber layer and eventually the optic nerve; 4. Inner plexiform layer - another layer of neuronal processes; 5. Inner nuclear layer; 6. Outer plexiform layer; 7. Outer nuclear layer; 8. External limiting membrane - layer separating inner segment portions of photoreceptors from their cell nuclei; 9. Photoreceptor layer - rods and cones that convert light into signals; 10. Retinal pigment epithelium).
- retinal pigment epithelium - (RPE) An epethial pigmented cell layer lying outside the sensory retina, formed from the outer layer of the folded optic cup. The RPE is firmly attached to the underlying choroid and overlying retinal visual cells, for which it has a nutritional role.
- retinal waves - A form of coordinated spontaneous activity that occurs in the developing retina. These waves of electrical activity (action potentials) along with EphA/ephrin-A signaling are thought to have a role in establishing the initial retinotopic map by correlating/coordinating the activity of neighbouring retinal ganglion cells.
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Cite this page: Hill, M.A. (2024, March 29) Embryology Sensory - Vision Development. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Sensory_-_Vision_Development
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