Difference between revisions of "Talk:Sensory - Vision Development"

From Embryology
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===Embryology of the eye and its adnexae===
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Dev Ophthalmol. 1992;24:1-142.
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Barishak YR.
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Sackler School of Medicine, University of Tel Aviv, Ramat Gan, Israel.
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Abstract
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The embryonal and fetal development of the human eye includes a series of sequential events starting with the fertilization of the ovum and culminating in the birth of a normal baby. Three main periods can be distinguished in the prenatal development of the eye. The first period called embryogenesis is characterized by the establishment of the primary organ rudiments and ends at the end of the 3rd week with the appearance of the optic sulci on both sides of the midline at the expanded cranial end of the still open neural folds. The second period called organogenesis includes the development of the primary organ rudiments and extends till the end of the 8th week. The third period involves the differentiation of each of the primitive organs into a fully or partially active organ and is called differentiation. The period of embryogenesis is characterized by the appearance and migration of the neural crest cells and by the formation of the primary brain vesicles. The period of organogenesis extends from the 4th week till the end of the 8th week. The 4th week shows the closure of the neural canal anteriorly with the subsequent evagination of its lateral wall into optic vesicles, the invagination of the lower nasal wall of the optic vesicle causing the formation of the optic cup, and the development of the lens plate, retinal disk and embryonic fissure. The embryonic fissure extends into the optic stalk which connects the cavity of the optic vesicle with the cavity of the neural canal; the hyaloid artery penetrates into the optic cup through the embryonic fissure. During the 5th week, the optic cup is concluded, and the cells of its external layer acquire pigmentation as a result of contact with developing capillaries in the periocular mesenchyme; these capillaries anastomose with each other and form anteriorly the annular vessel. The lens plate develops into a lens pit and later into a lens vesicle which separates soon thereafter from the surface ectoderm. Inside the optic cup, the hyaloid vessels form the capillaries of the posterior tunica vasculosa lentis and through the capillaries of the lateral tunica vasculosa lentis anastomose with the annular vessel. The primary vitreous forms and the surface ectoderm overlying the lens vesicle differentiates into a primitive corneal epithelium. The facial and orbital structures also develop at this stage. The 6th week shows the incipient differentiation of the inner layer of the optic cup into a sensory retina, the formation of the secondary vitreous, the transformation of the posterior cells of the lens vesicle into primary lens fibers, the development of the periocular vasculature and the appearance of the first eyelid folds and of the anlage of the nasolacrimal duct. However, the dominating factor is the closure of the embryonic fissure.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID: 1628748
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http://www.ncbi.nlm.nih.gov/pubmed/1628748
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==Eye Movement==
 
==Eye Movement==
 
* abducens nerve innervates the lateral rectus muscle
 
* abducens nerve innervates the lateral rectus muscle

Revision as of 13:12, 13 October 2010


Embryology of the eye and its adnexae

Dev Ophthalmol. 1992;24:1-142.

Barishak YR.

Sackler School of Medicine, University of Tel Aviv, Ramat Gan, Israel. Abstract The embryonal and fetal development of the human eye includes a series of sequential events starting with the fertilization of the ovum and culminating in the birth of a normal baby. Three main periods can be distinguished in the prenatal development of the eye. The first period called embryogenesis is characterized by the establishment of the primary organ rudiments and ends at the end of the 3rd week with the appearance of the optic sulci on both sides of the midline at the expanded cranial end of the still open neural folds. The second period called organogenesis includes the development of the primary organ rudiments and extends till the end of the 8th week. The third period involves the differentiation of each of the primitive organs into a fully or partially active organ and is called differentiation. The period of embryogenesis is characterized by the appearance and migration of the neural crest cells and by the formation of the primary brain vesicles. The period of organogenesis extends from the 4th week till the end of the 8th week. The 4th week shows the closure of the neural canal anteriorly with the subsequent evagination of its lateral wall into optic vesicles, the invagination of the lower nasal wall of the optic vesicle causing the formation of the optic cup, and the development of the lens plate, retinal disk and embryonic fissure. The embryonic fissure extends into the optic stalk which connects the cavity of the optic vesicle with the cavity of the neural canal; the hyaloid artery penetrates into the optic cup through the embryonic fissure. During the 5th week, the optic cup is concluded, and the cells of its external layer acquire pigmentation as a result of contact with developing capillaries in the periocular mesenchyme; these capillaries anastomose with each other and form anteriorly the annular vessel. The lens plate develops into a lens pit and later into a lens vesicle which separates soon thereafter from the surface ectoderm. Inside the optic cup, the hyaloid vessels form the capillaries of the posterior tunica vasculosa lentis and through the capillaries of the lateral tunica vasculosa lentis anastomose with the annular vessel. The primary vitreous forms and the surface ectoderm overlying the lens vesicle differentiates into a primitive corneal epithelium. The facial and orbital structures also develop at this stage. The 6th week shows the incipient differentiation of the inner layer of the optic cup into a sensory retina, the formation of the secondary vitreous, the transformation of the posterior cells of the lens vesicle into primary lens fibers, the development of the periocular vasculature and the appearance of the first eyelid folds and of the anlage of the nasolacrimal duct. However, the dominating factor is the closure of the embryonic fissure.(ABSTRACT TRUNCATED AT 400 WORDS)

PMID: 1628748 http://www.ncbi.nlm.nih.gov/pubmed/1628748



Eye Movement

  • abducens nerve innervates the lateral rectus muscle
  • trochlear nerve innervates the superior oblique (the dorsal oblique in chicks)
  • oculomotor nerve innervates the remaining four muscles, the medial, dorsal and ventral recti, and the inferior oblique



Gray's Anatomy: X. The Organs of the senses

the organ of sight

the tunics of the eye (Template:GraySubject)

the refracting media (Template:GraySubject)

the accessory organs of the eye (Template:GraySubject)


Neuron. 2007 Oct 25;56(2):327-38. Vision and cortical map development. White LE, Fitzpatrick D.

Department of Neurobiology, Duke University Medical Center, Durham, NC 27710, USA. len.white@duke.edu Abstract Functional maps arise in developing visual cortex as response selectivities become organized into columnar patterns of population activity. Recent studies of developing orientation and direction maps indicate that both are sensitive to visual experience, but not to the same degree or duration. Direction maps have a greater dependence on early vision, while orientation maps remain sensitive to experience for a longer period of cortical maturation. There is also a darker side to experience: abnormal vision through closed lids produces severe impairments in neuronal selectivity, rendering these maps nearly undetectable. Thus, the rules that govern their formation and the construction of the underlying neural circuits are modulated-for better or worse-by early vision. Direction maps, and possibly maps of other properties that are dependent upon precise conjunctions of spatial and temporal signals, are most susceptible to the potential benefits and maladaptive consequences of early sensory experience.

PMID: 17964249 [PubMed - indexed for MEDLINE]



Between molecules and experience: role of early patterns of coordinated activity for the development of cortical maps and sensory abilities. Hanganu-Opatz IL. Brain Res Rev. 2010 Sep;64(1):160-76. Epub 2010 Apr 8. PMID: 20381527

Visual maps: To merge or not to merge. Brewer AA. Curr Biol. 2009 Nov 3;19(20):R945-7. PMID: 19889370