Vision - Lens Development

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Introduction

Human lens development (Carnegie stage 22, Week 8)

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? 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).

The lens has recently been shown in the chicken model to not be required for specification of the iris and ciliary body.[1]


Vision Links: Introduction | Lens | Retina | Placodes | Extraocular Muscle | Cornea | Eyelid | Abnormalities | Student project 1 | Student project 2 | Category:Vision
Historic Embryology  
1906 Eye Embryology | 1907 Development Atlas | 1912 Eye Development | 1912 Nasolacrimal Duct | 1918 Grays Anatomy | 1921 Eye Development | 1922 Optic Primordia | 1925 Iris | 1927 Oculomotor | 1928 Retina | 1928 Hyaloid Canal | Historic Disclaimer

Some Recent Findings

  • Review - The cellular and molecular mechanisms of vertebrate lens development[2]| Development "The ocular lens is a model system for understanding important aspects of embryonic development, such as cell specification and the spatiotemporally controlled formation of a three-dimensional structure. The lens, which is characterized by transparency, refraction and elasticity, is composed of a bulk mass of fiber cells attached to a sheet of lens epithelium. Although lens induction has been studied for over 100 years, recent findings have revealed a myriad of extracellular signaling pathways and gene regulatory networks, integrated and executed by the transcription factor Pax6, that are required for lens formation in vertebrates."
  • Pax6-dependent, but β-catenin-independent, function of Bcl9 proteins in mouse lens development[3] "While lens development is critically dependent on the presence of the HD1 domain, it is not affected by the lack of the HD2 domain, indicating that Bcl9/9l act in this context in a β-catenin-independent manner. Furthermore, we uncover a new regulatory circuit in which Pax6, the master regulator of eye development, directly activates Bcl9/9l transcription."
  • On the growth and internal structure of the human lens[4] "Growth of the human lens and the development of its internal features are examined using in vivo and in vitro observations on dimensions, weights, cell sizes, protein gradients and other properties. In vitro studies have shown that human lens growth is biphasic, asymptotic until just after birth and linear for most of postnatal life."
  • Activated Ras alters lens and corneal development[5] "The murine lens and cornea have a common embryonic origin and arise from adjacent regions of the surface ectoderm. ...Collectively, these results suggest that Ras activation a) induces distinct sets of downstream targets in the lens and cornea resulting in distinct cellular responses and b) is sufficient for initiation but not completion of lens fiber differentiation."
More recent papers  
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This table shows an automated computer PubMed search using the listed sub-heading term.

  • Therefore the list of references do not reflect any editorial selection of material based on content or relevance.
  • References appear in this list based upon the date of the actual page viewing.

References listed on the rest of the content page and the associated discussion page (listed under the publication year sub-headings) do include some editorial selection based upon both relevance and availability.

Links: References | Discussion Page | Pubmed Most Recent | Journal Searches


Search term: Lens Embryology

Megan R Silas, Sarah M Hilkert, James J Reidy, Asim V Farooq Posterior keratoconus. Br J Ophthalmol: 2017; PubMed 29122822

Luisa Sanchez-Arrones, África Sandonís, Marcos Julián Cardozo, Paola Bovolenta Adenohypophysis placodal precursors exhibit distinctive features within the rostral preplacodal ectoderm. Development: 2017, 144(19);3521-3532 PubMed 28974641

Georgi As Georgiev, Petar Eftimov, Norihiko Yokoi Structure-function relationship of tear film lipid layer: A contemporary perspective. Exp. Eye Res.: 2017, 163;17-28 PubMed 28950936

Jacob B Burnett, Floria I Lupu, Jonathan T Eggenschwiler Proper ciliary assembly is critical for restricting Hedgehog signaling during early eye development in mice. Dev. Biol.: 2017; PubMed 28778798

Shivanand Chanabasu Bubanale, Santosh B Kurbet, Linda Maria Genoveva De Piedade Sequeira A rare case of cleft number nine associated with atypical cleft number two. Indian J Ophthalmol: 2017, 65(7);610-612 PubMed 28724820

Development Overview

surface ectoderm -> lens placode -> lens pit -> lens vesicle -> lens fibres -> lens capsule and embryonic/fetal nucleus.

Week 4

Human Embryo Carnegie stage 11
Human Embryo Carnegie stage 12

Stage11 histology-optic pit.jpg

Human Embryo Carnegie stage 11 optic pit

Week 5

Human Embryo Carnegie stage 13

Stage 13 image 058.jpg Stage 13 image 059.jpgStage 13 image 060.jpgStage 13 image 061.jpg

Week 8

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

 ‎‎Mobile | Desktop | Original

Stage 22 | Embryo Slides

Virtual Slide - Regions of Interest

Links: Carnegie stage 22 | Embryo Virtual Slides

Molecular Signaling

Eye-neural crest signaling.jpg

Wnt mediates lens repression by neural crest cells and Transforming growth factor-β[6] (open image for full description)

Links: Lens Development | Neural Crest Development | Wnt | Lens repression by neural crest cells | Proposed model how NCCs organize the eye | molecular model to explain TGF-β- and Wnt-mediated lens restriction

References

  1. Magnus R Dias da Silva, Nicola Tiffin, Tatsuo Mima, Takashi Mikawa, Jeanette Hyer FGF-mediated induction of ciliary body tissue in the chick eye. Dev. Biol.: 2007, 304(1);272-85 PubMed 17275804
  2. Aleš Cvekl, Ruth Ashery-Padan The cellular and molecular mechanisms of vertebrate lens development. Development: 2014, 141(23);4432-47 PubMed 25406393
  3. Claudio Cantù, Dario Zimmerli, George Hausmann, Tomas Valenta, Andreas Moor, Michel Aguet, Konrad Basler Pax6-dependent, but β-catenin-independent, function of Bcl9 proteins in mouse lens development. Genes Dev.: 2014, 28(17);1879-84 PubMed 25184676
  4. Robert C Augusteyn On the growth and internal structure of the human lens. Exp. Eye Res.: 2010, 90(6);643-54 PubMed 20171212
  5. Daniel Burgess, Yan Zhang, Ed Siefker, Ryan Vaca, Murali R Kuracha, Lixing Reneker, Paul A Overbeek, Venkatesh Govindarajan Activated Ras alters lens and corneal development through induction of distinct downstream targets. BMC Dev. Biol.: 2010, 10;13 PubMed 20105280
  6. Grocott T, Johnson S, Bailey AP, Streit A. Neural crest cells organize the eye via TGF-β and canonical Wnt signalling. Nat Commun. 2011 Apr;2:265. PMID21468017 | Nat Commun.

Additional Images

Historic Images

Historic Disclaimer - information about historic embryology pages 
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Pages where the terms "Historic Textbook" and "Historic Embryology" appear on this site, and sections within pages where this disclaimer appears, indicate that the content and scientific understanding are specific to the time of publication. This means that while some scientific descriptions are still accurate, the terminology and interpretation of the developmental mechanisms reflect the understanding at the time of original publication and those of the preceding periods, these terms and interpretations may not reflect our current scientific understanding.     (More? Embryology History | Historic Embryology Papers)

Streeter GL. Developmental Horizons In Human Embryos Description Or Age Groups XIX, XX, XXI, XXII, And XXIII, Being The Fifth Issue Of A Survey Of The Carnegie Collection. (1957) Carnegie Instn. Wash. Publ. 611, Contrib. Embryol., 36: 167-196.

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Cite this page: Hill, M.A. 2017 Embryology Vision - Lens Development. Retrieved November 18, 2017, from https://embryology.med.unsw.edu.au/embryology/index.php/Vision_-_Lens_Development

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© Dr Mark Hill 2017, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G