Vision - Cornea Development

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Cornea structure
Human embryonic cornea
Human embryonic cornea (Week 8, Carnegie stage 22)
Human embryonic cornea
Human embryonic cornea detail (Week 8, Carnegie stage 22)
Section through front of Eyeball
Section through human cornea

These notes introduce the development of the cornea of the eye. The adult cornea has three layers: an outer epithelium layer (ectoderm), a middle stromal layer of collagen-rich extracellular matrix between stromal keratocytes (neural crest) and an inner layer of endothelial cells (neural crest).

The cornea is a vision-specific specialised sensory epithelia that in humans differentiates mainly in the postnatal period. It arises initially from cranial ectoderm adjacent to the lens placode and forms a presumptive corneal epithelium. Later neural crest cells migrate between the lens and presumptive structure to form both the corneal endothelium and the stromal fibroblasts (keratocytes). Neural crest development in humans, reptiles and birds differs from that seen in rodents, cats, rabbits, and cattle.

Vision Links: vision | lens | retina | placode | extraocular muscle | cornea | eyelid | lacrima gland | vision abnormalities | Student project 1 | Student project 2 | Category:Vision | sensory
Historic Embryology - Vision 
Historic Embryology: 1906 Eye Embryology | 1907 Development Atlas | 1912 Eye Development | 1912 Nasolacrimal Duct | 1917 Extraocular Muscle | 1918 Grays Anatomy | 1921 Eye Development | 1922 Optic Primordia | 1925 Eyeball and optic nerve | 1925 Iris | 1927 Oculomotor | 1928 Human Retina | 1928 Retina | 1928 Hyaloid Canal | Historic Disclaimer
Links: Category:Cornea | Neural Crest Development | Integumentary Development

Some Recent Findings

  • Review - Corneal Development Different Cells from a Common Progenitor[1] "Development of the vertebrate cornea is a multistep process that involves cellular interactions between various ectodermal-derived tissues. Bilateral interactions between the neural ectoderm-derived optic vesicles and the cranial ectoderm give rise to the presumptive corneal epithelium and other epithelia of the ocular surface. Interactions between the neural tube and the adjacent ectoderm give rise to the neural crest cells, a highly migratory and multipotent cell population. Neural crest cells migrate between the lens and presumptive corneal epithelium to form the corneal endothelium and the stromal keratocytes. The sensory nerves that abundantly innervate the corneal stroma and epithelium originate from the neural crest- and ectodermal placode-derived trigeminal ganglion."
  • Bovine cornea extracellular matrix structure[2] "Electron microscopy and X-ray fibre diffraction were used to ascertain collagen fibril architecture. The bovine cornea was 1021±5.42μm thick at its outer periphery, defined as 9-12mm from the corneal centre, compared to 844±8.10μm at the centre. The outer periphery of the cornea was marginally, but not significantly, more hydrated than the centre (H=4.3 vs. H=3.7), and was more abundant in hydroxyproline (0.12 vs. 0.06mg/mg dry weight of cornea). DMMB assays indicated no change in the total amount of sulphated GAG across the cornea. Immunohistochemistry revealed the presence of both high- and low-sulphated epitopes of KS, as well as DS, throughout the cornea, and CS only in the peripheral cornea before the limbus. Quantification by ELISA, disclosed that although both high- and low-sulphated KS remained constant throughout stromal depth at different radial positions, high-sulphated epitopes remained constant from the corneal centre to outer-periphery, whereas low-sulphated epitopes increased significantly.
More recent papers  
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Carnegie Stages - Eye

Human Eye Development
Carnegie Stage Event
10 optic primordia appear.
11 Right and left optic primordia meet at the optic chiasma forming a U-shaped rim.
12 optic neural crest reaches its maximum extent and the optic vesicle becomes covered by a complete sheath,
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.
14 (about 32 days) Lens placode is indented by the lens pit, cup-shaped and still communicates with the surface by a narrowing pore.
15 (about 33 days) Lens pit is closed. The lens vesicle and optic cup lie close to the surface ectoderm and appear to press against the surface.
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.
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.
18 Mesenchyme invades the region between the lens epithelium and the surface ectoderm.
19 - 22 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.
20 Lens cavity is lost and a lens suture begins to form. The inner canthus is established.
23 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).
Data from a study of human embryonic carnegie stages[3] and other sources.
Week: 1 2 3 4 5 6 7 8
Carnegie stage: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23

Human Cornea

Week 8 Stage 22

The images below link to virtual slides of the human developing eye at Carnegie stage 22. Click on the image to open or select specific regions from the regions of interest links.

Stage 22 - Eye and Nose

Stage 22 image 008.jpg

 ‎‎Mobile | Desktop | Original

Stage 22 | Embryo Slides
Stage 22 - Eye

Stage 22 image 008-eye.jpg

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Stage 22 | Embryo Slides

Virtual Slide - Regions of Interest

Links: Embryo Virtual Slides

Cornea Epithelia

The cornea ocular surface is composed of three epithelia, conjunctival, limbal and corneal.
  • Limbal stem cells are located in the palisades of Vogt, the transitional zone between the cornea and the conjunctiva.
  • Limbal stem cells are close to blood vessels.
  • They generate transient amplifying cells that terminally differentiate after a discrete number of cell divisions to corneal epithelial cells and undergo both centripetal migration and vertical migration.
Corneal Epithelial Cells cartoon

Corneal epithelial cells cartoon[4]

The Adult Human Limbal Palisades of Vogt
  • A - Palisades of Vogt (arrow) are readily recognized in the human limbus.
  • B - Such a unique pigmented structure can be identified on the flat mount preparation of Dispase-isolated human limbal epithelial sheets.
  • C - In donors with a darker skin, these palisades of Vogt are pigmented (arrow).
  • D - Under higher magnification, these limbal areas show undulated epithelial papillae (stars).
  • E - Hematoxyline staining highlights higher stratification and more undulation of the limbal epithelium, and the underlying limbal stroma has high cellularity and vascularity (arrow shows blood vessel).

Bar represents 500 μm in A and B, 200 μm in C and E, and 50 μm in D

Adult human limbal palisades of Vogt

Adult human limbal palisades of Vogt[5]

Limbal Stem Cells

Limbal stem cell niche cartoon PMID17211449.jpg

Cartoon showing the location of limbal stem cells at the limbal basal layer.[5]

Links: Stem Cells

Descemet Membrane

Corneal endothelium basement membrane beginning in children at 3 μm thick and increases in adults to 10 μm. Consists of collagen type IV and VIII fibrils.

Composed of two layers:

  1. anterior banded layer - commencing in week 10 (GA week 12) as collagen lamellae and proteoglycans.
  2. posterior non-banded layer - deposited by endothelial cells over time and thickens postnatally over decades.

Descemet membrane was historically named after Jean Descemet (1732–1810) a French physician.

Palisades of Vogt

The palisades of Vogt are a series of radially oriented fibrovascular ridges concentrated along the upper and lower corneoscleral limbus, the vasculature component consists of radially oriented hairpin loops of narrow arterial and venous vessels. Named by Vogt in 1921. (for review see[6])

Aggregate into distinct crescentic zones and lie peripheral to the terminal capillary loops of the limbus and central to Schlemm’s canal. Lying between the connective tissue palisades are intervening radial zones of thickened conjunctival epithelium, the so-called inter-palisades or epithelial rete ridges.

Mouse Cornea

histology Mouse eye neural crest

Neural crest-derived cells contribute to mouse cornea development.[7]

  • a Toluidine blue staining of an adult eye. The boxed areas correspond to b and c
  • b A detailed view of the corneal assembly, including outer epithelium, stroma, and inner endothelium
  • c The chamber angle at the irido-corneal transition which includes the trabecular meshwork (tm).
  • d-j In vivo fate mapping of NC-derived, β-galactosidase (βGal)-expressing cells (blue)
  • d The NC origin of corneal keratocytes (arrows) and of corneal endothelium (arrowhead).
  • e Structures of the chamber angle, including the trabecular meshwork are seen to be NC-derived.
  • f At E10, the optic cup is surrounded by NC-derived cells expressing βGal.
  • g-i The majority of the cells in the periocular mesenchyme (arrows), which forms the anterior eye segment, are of NC origin, as assessed from E11.5 to E13.5.
  • j The primary vitreous at E13.5 (arrowheads) shows a strong NC contribution.

Frog Cornea

This developmental timeline is from a recent frog (Xenopus laevis) cornea study[8]

  • stage 25 - cornea starts from a simple embryonic epidermis overlying the developing optic vesicle.
  • stage 30 - detachment of the lens placode, cranial neural crest cells start to invade the space between the lens and the embryonic epidermis to construct the corneal endothelium.
  • stage 41 - a second wave of migratory cells containing presumptive keratocytes invades the matrix leading to the formation of inner cornea and outer cornea. A unique cell mass (stroma attracting center) connects the two layers like the center pole of a tent.
  • stage 48 - many secondary stromal keratocytes individually migrate to the center and form the stroma layer.
  • stage 60 - the stroma space is filled by collagen lamellae and keratocytes, and the stroma attracting center disappears. At early metamorphosis, the embryonic epithelium gradually changes to the adult corneal epithelium, which is covered by microvilli.
  • stage 62 - the embryonic epithelium thickens and cell death is observed in the epithelium, coinciding with eyelid opening.
  • After metamorphosis - cornea has attained the adult structure of three cellular layers, epithelium, stroma, and endothelium, and between the cellular layers lie two acellular layers (Bowman's layer and Descemet's membrane)

Xenopus cornea development timeline

Links: Frog Development


Mouse eye TGF-beta model.jpg

Mouse Eye TGF-beta Model - Summary of the TGFβ-dependent development of anterior and posterior ocular structures.[7]

a Neural crest-derived cells (NC, blue) contribute to structures of the anterior eye segment and the primary vitreous (PV).
  • TGFβ signaling is involved in the formation of the ciliary body (CB) and the trabecular meshwork (TM), and in control of PV growth.
  • Moreover, normal PV development and/or TGFβ signaling are important for correct retinal patterning.
b In the cornea, prospective stromal keratocytes and endothelial cells are of neural crest origin.
  • Here, TGFβ signaling is needed for the expression of the transcription factors Foxc1 and Pitx2 and for normal differentiation of NC-derived cells into collagen-synthesizing stromal keratocytes.
  • Moreover, in forming corneal endothelial cells (and in the TM), expression of Foxc1 and cell survival requires TGFβ signalling.

Additional Images

Historic Images


  1. Lwigale PY. (2015). Corneal Development: Different Cells from a Common Progenitor. Prog Mol Biol Transl Sci , 134, 43-59. PMID: 26310148 DOI.
  2. Ho LT, Harris AM, Tanioka H, Yagi N, Kinoshita S, Caterson B, Quantock AJ, Young RD & Meek KM. (2014). A comparison of glycosaminoglycan distributions, keratan sulphate sulphation patterns and collagen fibril architecture from central to peripheral regions of the bovine cornea. Matrix Biol. , 38, 59-68. PMID: 25019467 DOI.
  3. Pearson AA. (1980). The development of the eyelids. Part I. External features. J. Anat. , 130, 33-42. PMID: 7364662
  4. Kayama M, Kurokawa MS, Ueno H & Suzuki N. (2007). Recent advances in corneal regeneration and possible application of embryonic stem cell-derived corneal epithelial cells. Clin Ophthalmol , 1, 373-82. PMID: 19668514
  5. 5.0 5.1 Li W, Hayashida Y, Chen YT & Tseng SC. (2007). Niche regulation of corneal epithelial stem cells at the limbus. Cell Res. , 17, 26-36. PMID: 17211449 DOI.
  6. Goldberg MF & Bron AJ. (1982). Limbal palisades of Vogt. Trans Am Ophthalmol Soc , 80, 155-71. PMID: 7182957
  7. 7.0 7.1 Ittner LM, Wurdak H, Schwerdtfeger K, Kunz T, Ille F, Leveen P, Hjalt TA, Suter U, Karlsson S, Hafezi F, Born W & Sommer L. (2005). Compound developmental eye disorders following inactivation of TGFbeta signaling in neural-crest stem cells. J. Biol. , 4, 11. PMID: 16403239 DOI.
  8. Hu W, Haamedi N, Lee J, Kinoshita T & Ohnuma S. (2013). The structure and development of Xenopus laevis cornea. Exp. Eye Res. , 116, 109-28. PMID: 23896054 DOI.


  • Cornea "For corneal specialists and for all general ophthalmologists with an interest in this exciting subspecialty, Cornea brings together the latest clinical and basic research on the cornea and the anterior segment of the eye." [jour PuMed Listing]


Lwigale PY. (2015). Corneal Development: Different Cells from a Common Progenitor. Prog Mol Biol Transl Sci , 134, 43-59. PMID: 26310148 DOI.

Maycock NJ & Marshall J. (2014). Genomics of corneal wound healing: a review of the literature. Acta Ophthalmol , 92, e170-84. PMID: 23819758 DOI.

Hassell JR & Birk DE. (2010). The molecular basis of corneal transparency. Exp. Eye Res. , 91, 326-35. PMID: 20599432 DOI.

Masters BR. (2009). Correlation of histology and linear and nonlinear microscopy of the living human cornea. J Biophotonics , 2, 127-39. PMID: 19343693 DOI.

The International Journal of Developmental Biology Vol. 48 Nos. 8/9 (2004) Eye Development


MAURICE DM. (1957). The structure and transparency of the cornea. J. Physiol. (Lond.) , 136, 263-86. PMID: 13429485

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  • Limbal epithelial stem cells - cells located at the limbal basal layer.
  • palisades of Vogt - series of radially oriented fibrovascular ridges concentrated along the upper and lower corneoscleral limbus, the vasculature component consists of radially oriented hairpin loops of narrow arterial and venous vessels. Named by Vogt in 1921. PMID 7182957


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