2009 Lecture 19

From Embryology

Vision

--Mark Hill 12:49, 24 September 2009 (EST) This lecture is currently timetabled for a day that is a public holiday. The content will be covered as part of last week's laboratory. I will still add the appropriate lecture notes here.

Introduction

The adult eye has contributions from several different embryonic layers eventually forming neuronal, supportive connective tissue, optical structures, and muscular tissues.


2008: 2008 Lecture Vision | 1 slide/page viewing 48 pages | 4 slide/page viewing 12 pages | Lecture Audio - 25 Sep 2008 - 13:00 55 min

Development Timing

  • Week 3 - beginning of "eye fields" of neural tube at the level of the prosencephalon.
  • Week 4 - optic sulci form as indentations at the level of the diencephalon which extend towards and then contact the surface ectoderm.


(These are Human embryonic timings, not clinical which is based on last menstral period +2 weeks)

Embryonic Eye

Stage 13/14 Embryo

The human embryo Carnegie stage 13 day 42 6mm (CRL), these are pig embryo sections.

Embryo stage 13 show the optic vesicles and lens placode. Image alone

Stage 22 Embryo

The human embryo Carnegie stage 22 is 27mm (CRL) in size and approximately equal to day 54 - 56 of development.

Embryo stage 22 show eye structures (anterior chamber, lens, posterior chamber, retina, optic nerve, nasolacrimal duct, extraocular muscles) .

Embryo stage 22 show detailed selected regions (shown in blue boxes) of the eye covering optic nerve, retina (neural and pigmented) and lens. Click the next page link to see detailed sections: retina, pigmented retina, sclera and muscles | high power showing optic cup layers and opic ventricle | lens, anterior and posterior chambers, cornea and developing iris

Adult Retina

Vertebrates have ten identifiable layers formed from neurons, their processes (nerve fibers), 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 - retinal ganglion axons eventually the optic nerve.
  3. Ganglion cell layer - neuronal cell bodies 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 - neuronal cell bodies
  6. Outer plexiform layer - another layer of neuronal processes.
  7. Outer nuclear layer - neuronal cell bodies
  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.

References

Textbooks

  • Human Embryology (2nd ed.) Larson Chapter 12: p375-409
  • The Developing Human: Clinically Oriented Embryology (6th ed.) Moore and Persaud Chapter 19: p491-511
  • Essentials of Human Embryology Larson Chapter 12: p252-272
  • Before We Are Born (5th ed.) Moore and Persaud Chapter 20: p460-479

Bookshelf

Developmental Biology (6th ed.) Gilbert, Scott F. Sunderland (MA): Sinauer Associates, Inc.; c2000. Development of the Vertebrate Eye

Molecular Biology of the Cell (4th ed.) Alberts, Bruce; Johnson, Alexander; Lewis, Julian; Raff, Martin; Roberts, Keith; Walter, Peter. New York: Garland Publishing; 2002. The Formation of an Entire Organ Can Be Triggered by a Single Gene Regulatory Protein | Sensory Epithelia

Neuroscience (2nd ed.) Purves, Dale; Augustine, George.J.; Fitzpatrick, David; Katz, Lawrence.C.; LaMantia, Anthony-Samuel.; McNamara, James.O.; Williams, S. Mark, editors. Sunderland (MA): Sinauer Associates, Inc. 2001 Critical Periods in Visual System Development | Figure 11.3. Development of the human eye | Effects of Visual Deprivation on Ocular Dominance |

Genes and disease Bethesda (MD): National Library of Medicine (US), NCBI. Diseases of the Eye


Terms

eye field - region initially located as a large single domain at the anterior end of the neural plate that will later contribute to eye development.

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 (nerve fibers, neurons, membranes, photoreceptors and pigmented cells) and light must pass through nearly all these layers to the photoreceptors.

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.

Glossary Links

Glossary: A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z | Numbers | Symbols | Term Link

Course Content 2009

Embryology Introduction | Cell Division/Fertilization | Cell Division/Fertilization | Week 1&2 Development | Week 3 Development | Lab 2 | Mesoderm Development | Ectoderm, Early Neural, Neural Crest | Lab 3 | Early Vascular Development | Placenta | Lab 4 | Endoderm, Early Gastrointestinal | Respiratory Development | Lab 5 | Head Development | Neural Crest Development | Lab 6 | Musculoskeletal Development | Limb Development | Lab 7 | Kidney | Genital | Lab 8 | Sensory - Ear | Integumentary | Lab 9 | Sensory - Eye | Endocrine | Lab 10 | Late Vascular Development | Fetal | Lab 11 | Birth, Postnatal | Revision | Lab 12 | Lecture Audio | Course Timetable


Cite this page: Hill, M.A. (2019, March 22) Embryology 2009 Lecture 19. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/2009_Lecture_19

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© Dr Mark Hill 2019, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G