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Embryology /organogenesis/

Embryology /organogenesis/. Development and teratology of nervous system. NOTOCHORD DEVELOPMENT. Neuroectoderm Neural plate. NOTOCHORD induces neural plate development. Neural plate – thickened area of embryonic ectoderm  neuroectoderm. pseudostratif. columnar ep. Pharyngeal

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Embryology /organogenesis/

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  1. Embryology/organogenesis/ Development and teratology of nervous system.

  2. NOTOCHORD DEVELOPMENT Neuroectoderm Neural plate NOTOCHORD • induces neural plate development

  3. Neural plate – thickened area of embryonic ectoderm  neuroectoderm pseudostratif. columnar ep. Pharyngeal membrane Primitive streak and node Notochord Cloacal membrane

  4. NEURULATION– invagination of neural plate (day 16 - 24) • neural folds • neural groove • neural tube • neural crest notochord

  5. Day 20 Neural folds

  6. Day 22, 23 Neuroporus anterior closes on D 25 closes on D 27 Neuroporus posterior

  7. NEURAL CREST

  8. Odontoblasts Leptomeningeal cells

  9. EKTOMESENCHYME

  10. Histogenesis of neural tube The wall of neural tube: (simple → pseudostratified neural epithelium) Cell proliferation  3 zones: EpendymalIntermediateMarginal zone Ependyma Gray matter White matter (in medulla spinalis)

  11. HISTOGENESIS of NEURAL TUBE Marginal zone (white matter) Intermediate zone (gray matter) (mantle zone) Ependymal zone (germinal)

  12. Histogenesis of neural tissue In spinal cord white matter gray matter ependyme Three zones line neural tube (the spinal cord and brain stem). Marginal zone (white matter) – without neurons, but with axons ofneurons and glial cells Mantle zone (gray matter) – neuroblasts + spongioblasts give rise to bodies of neurons and glial cells Ependymal zone (germinal) – lining of central canal

  13. In brain and cerebellum gray matter white matter ependyme In brain and cerbellum: mantle zone cells migrate through marginal layer and the gray matter coveres white matter. Some neurons stay in white matter  nuclei.

  14. Spinal cord development Dorsal horns future white matter sensory zone future gray matter motor zone Ventral horns

  15. SPINAL CORD: • Ependymal layer (germinal) • Mantle layer (gray matter) • Marginal layer (white matter)

  16. Positional changes of spinal cord the end fo the 2nd month the 5th month new-born child # Vertebrate canal grows more rapidly than spinal cord and caudal end of spinal cord doesn‘t extend the entire length of canal in adult; it terminates at L2 in adults # . pia mater Cauda equina

  17. Brain development • Brain developsfromcranial part ofneural tube • Week 4 – threeprimary brain vesicles: - prosencephalon (forebrain) - mesencephalon (midbrain) - rhombencephalon (hindbrain)

  18. 3 primary → 5 secondary vesicles: week 5 Lamina terminalis week 4 Telencephalon 1 Diencephalon 2 Prosencephalon Mesencephalon Rhombencephalon Optic vesicle Neurohypophysis Epiphysis 3 4 Metencephalon Cerebellum Pons Myelencephalon 1 – ventriculi lat., 2 – ventriculus tertius, 3 – aqueductus cerebri, 4 – ventriculus quartus

  19. Midbrainflexure Cervicalflexure

  20. Myelination of nerve fibers from the 4th prenatal month to the end of 2nd postnatal year

  21. CNS malformations • failureneurulation (absence ofnotochordinductive influence or teratogen influence on neuroectodermalcells) • defectsofspinalcord • defectsof brain • difficultmalformationsof CNS are usuallyconnectedwithskullorspinalcolumn (vertebral) defects. Etiology: usuallymultifactorial (fever, drugsduring gravidity, hypervit. A etc.) orhereditarydisposition. Folic acid use influence normaldevelopmentof CNS. Sonographydetectsanomalies.

  22. Spinal cord malformations Defects (clefts) of vertebral arches • Menigocele • Menigomyelocele • Menigohydromyelocele • Myeloschisis – complete cleft of spinal column in the whole length spina bifida cystica

  23. Examples of external signs of spina bifida: 1) hairy patch 2) hemangioma Urodynamics 3) skin appendage 4) lipomatous mass

  24. Brain malformations • Anencephalia (†) (with myeloschisis)

  25. Brain malformations MICROCEPHALIA ANENCEPHALIA

  26. Hydrocephalus • accumulationofabundantcerebrospinal fluid in brain ventricularsystem, • etiology: stenosisorobliterationofaqueductuscerebribetween 3rd and 4th ventricles fluid isaccumulated in lateralventriclespushes on the brain tissue (isthinned); internalpressurecomplicatesdrenageof fluid insubarachnoidspace; • untilskullsuturedon‘tossify – skullcangrowsextremely .

  27. HYDROCEPHALUS ventriculoperitoneal shunt

  28. Brain and meninges hernia(tion)

  29. Neurohypophyseal diverticle of diencephalon floor + Rathke‘s pouch of stomodeum roof

  30. Pineal gland (epiphysis) – diverticulum of the roof of diencephalon the floor of diencephalon

  31. Thyroid gland

  32. Descensus of thyroid gland Ductus thyroglossus Ultimobranchial body – the 4th endodermal pouch – parafollicular cells

  33. CORTEX • mesoderm • (coelomicepithelium) • MEDULLA • neuroectoderm • (neuralcrest)

  34. Terms • Neuron – perikaryon – axon (= neurite) – dendrite(s) • Nissl bodies = rough ER • Axon hillock • Myeline sheath • Schwann sheath • Mesaxon • Internodium • Node of Ranvier • Neuron – classification • Synapse (presynaptic knobe, synaptic cleft, postsynaptic memrane) • Neurotransmitters

  35. Terms • Neuroglia - classification • Oligodendroglia • Astrocytes • Microglia (of Horteg) • Ependyma - tanycytes • Schwann cells • Satelite cells in CNS in PNS

  36. Special histology - questions • Structure of the brain cortex. Cyto- and myeloarchitecture. • Structure of the cerebellum. Synapses of the cerebellum. • Microscopic structure of the spinal cord. • Microscopic structure of ganglia and peripheral nerves. • Ependyma, plexus chorioideus and meninges.

  37. Terms • Brain cortex – 6 layers (lamina) • Cajal cells, Martinotti cells, granular and pyramidal cells • Membrana limitans gliae superficialis et profunda (seu perivascularis) • Brain barrier • Cerebellum – 3 layers of cortex (stratum) • Purkinje cells, basket cells, granular cells • Glomeruli cerebellares • Mossy and climbing fibers

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