Dog Optic Development Quiz
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Questions and Answers

During which day of gestation in the dog are the optic sulci visible?

  • Day 17
  • Day 13 (correct)
  • Day 19
  • Day 15

    • What happens concurrently with the transformation from optic sulcus to optic vesicle in the dog?

  • Enlargement of the optic vesicle
  • Closure of the neural tube (correct)
  • Development of the optic stalk
  • Formation of the lens placode

    • What is the role of the optic vesicle in the development of the dog's palpebral fissure and orbital structures?

  • Enlargement of the optic vesicle
  • Formation of the lens placode
  • Invagination through differential growth
  • Induction and size determination (correct)

    • Which structure develops from mesenchyme in the optic fissure?

    <p>Hyaloid artery</p> Signup and view all the answers

    What happens if the optic fissure fails to close normally?

    <p>Formation of colobomas</p> Signup and view all the answers

    What is the role of the optic vesicle in lens formation?

    <p>It induces lens differentiation</p> Signup and view all the answers

    What is the initial event leading to the formation of the chambers of the ocular anterior segment?

    <p>Lens vesicle detachment</p> Signup and view all the answers

    Which structure surrounds the lens vesicle and will become the lens capsule?

    <p>Basal lamina</p> Signup and view all the answers

    What is the embryonic lens nucleus composed of in the adult?

    <p>Primary lens fibers</p> Signup and view all the answers

    What continues to develop from the anterior cuboidal epithelial cells in the lens?

    <p>Lens cortex</p> Signup and view all the answers

    What is the term used for the zonule fibers in the lens?

    <p>Tertiary vitreous</p> Signup and view all the answers

    Which structure is responsible for promoting primary lens fiber formation in the lens epithelial cells?

    <p>The retinal primordium</p> Signup and view all the answers

    What is the term used for the central sphere inside the 'Y' sutures in the adult lens?

    <p>Lens nucleus</p> Signup and view all the answers

    What is the origin of the zonule fibers in the lens?

    <p>Embryonic TVL</p> Signup and view all the answers

    What could result in congenital ectopia lentis?

    <p>Lens coloboma</p> Signup and view all the answers

    What is the shape of the lens fibers in the lens?

    <p>Hexagonal</p> Signup and view all the answers

    What is the term used for the elongation of lens epithelial cells nearest the presumptive retina?

    <p>Lens fiber elongation</p> Signup and view all the answers

    What is the embryonic lens nucleus composed of in the adult lens?

    <p>Lens fibers</p> Signup and view all the answers

    What happens if the optic fissure fails to close normally?

    <p>Development of lens coloboma</p> Signup and view all the answers

    What is the term used for the secondary lens fibers that course anteriorly and posteriorly around the embryonal nucleus?

    <p>Y sutures</p> Signup and view all the answers

    What is the term used for the localized absence of zonules in the lens?

    <p>Lens coloboma</p> Signup and view all the answers

    During which day of gestation in the dog do the optic sulci become visible?

    <p>Day 13</p> Signup and view all the answers

    What is the term used to describe the transformation from optic sulcus to optic vesicle?

    <p>Invagination</p> Signup and view all the answers

    What contributes to the expansion of the optic vesicle?

    <p>Localized proliferation and cell growth</p> Signup and view all the answers

    At approximately which day of gestation in the dog can an external bulge indicating the presence of the enlarging optic vesicle be seen?

    <p>Day 17</p> Signup and view all the answers

    What is the role of the optic vesicle in the development of the palpebral fissure and orbital structures in the dog?

    <p>Induction and size determination</p> Signup and view all the answers

    What occurs during the invagination of the optic vesicle?

    <p>Local apical contraction and physiologic cell death</p> Signup and view all the answers

    What structure forms when the surface ectoderm in contact with the optic vesicle thickens?

    <p>Lens placode</p> Signup and view all the answers

    What happens as the space within the optic vesicle collapses during lens formation?

    <p>The invaginating neural ectoderm folds onto itself</p> Signup and view all the answers

    What is the embryonic lens nucleus composed of in the adult?

    <p>Lens fibers</p> Signup and view all the answers

    What surrounds the lens vesicle and will become the lens capsule?

    <p>Basal lamina</p> Signup and view all the answers

    During which day of gestation in the dog does the hyaloid artery develop from mesenchyme in the optic fissure?

    <p>Day 25</p> Signup and view all the answers

    What is the consequence of the failure of the optic fissure to close normally?

    <p>Formation of colobomas in the iris</p> Signup and view all the answers

    What is the protein content in the embryonic vitreous humor derived from?

    <p>Plasma proteins entering the eye by diffusion</p> Signup and view all the answers

    What is the role of the optic vesicle in lens formation?

    <p>It gives the surface ectoderm a lens-forming bias</p> Signup and view all the answers

    What is the initial event leading to the formation of the chambers of the ocular anterior segment?

    <p>Lens vesicle detachment</p> Signup and view all the answers

    What may result from faulty keratolenticular separation?

    <p>All of the above</p> Signup and view all the answers

    What is the consequence of abnormal orientation of the optic vesicle as it approaches the surface ectoderm?

    <p>Formation of a lens vesicle in an abnormal location</p> Signup and view all the answers

    What is the size of the lens vesicle determined by?

    <p>The contact area of the optic vesicle with the surface ectoderm</p> Signup and view all the answers

    What is aplasia a result of in lens development?

    <p>Both A and B</p> Signup and view all the answers

    What is one of the characteristics of teratogen-induced anterior segment dysgenesis in animal models?

    <p>Faulty keratolenticular separation</p> Signup and view all the answers

    Study Notes

    Development of the Optic System in Dogs

    • Optic sulci become visible around day 22 of gestation in dogs.
    • The transformation from optic sulcus to optic vesicle occurs concurrently with the folding of the neural ectoderm.
    • Optic vesicle plays a crucial role in the development of the palpebral fissure and surrounding orbital structures by influencing the growth and positioning of these tissues.
    • Mesenchyme in the optic fissure gives rise to the hyaloid artery.
    • If the optic fissure fails to close normally, it can result in congenital defects such as coloboma.
    • The optic vesicle is instrumental in lens formation by inducing the overlying ectoderm to thicken and form the lens placode.

    Lens Development and Structure

    • Initial events leading to the formation of the chambers of the ocular anterior segment begin with the invagination of the lens placode.
    • The lens vesicle is surrounded by a structure that will develop into the lens capsule.
    • The embryonic lens nucleus consists of cells that mature to form the central, transparent core of the lens.
    • Anterior cuboidal epithelial cells in the lens continue to develop into secondary lens fibers.
    • Zonule fibers, also known as zonules of Zinn, connect the ciliary body to the lens.
    • Primary lens fiber formation in lens epithelial cells is promoted by growth factors from the optic vesicle.

    Lens Fiber Characteristics

    • The central sphere inside the 'Y' sutures in the adult lens is termed the embryonic lens nucleus.
    • Zonule fibers originate from the periocular mesenchyme during development.
    • A congenital condition known as ectopia lentis may arise due to improper formation of zonules.
    • Lens fibers are elongated, providing structural support and transparency.
    • Elongation of lens epithelial cells nearest the presumptive retina is referred to as lens fiber differentiation.
    • Secondary lens fibers extend anteriorly and posteriorly around the embryonal nucleus, complementing lens formation.

    Spatio-temporal Aspects

    • At approximately day 24 of gestation, an external bulge indicating the enlarging optic vesicle can be observed.
    • Invagination of the optic vesicle results in the formation of the lens vesicle.
    • Failure of optic fissure closure can lead to significant ocular anomalies, disrupting normal eye development.
    • Abnormal orientation of the optic vesicle can hinder proper lens and surrounding structure formation.
    • The size of the lens vesicle is determined by interactions with the surrounding tissues, including the optic vesicle.
    • Aplasia in lens development occurs due to genetic factors or teratogens disrupting normal signaling pathways.

    Teratogenic Influences

    • Teratogen-induced anterior segment dysgenesis in animal models exhibits various characteristics like abnormal lens and corneal development.
    • The protein content of the embryonic vitreous humor is derived from cellular components and signals within the developing eye structures.

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    Description

    Test your knowledge on the development of optic sulci and the transformation into optic vesicles in dogs.

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