Talk:Lecture - Ectoderm Development

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Lecture 6 - Ectoderm Development Lecture Date: 20 August 2013 Lecture Time: 16:00 Venue: Biomedical Theatre E Speaker: Annemiek Beverdam. The lecture slides can be found here: File:ANAT2341 Lecture 4 - Beverdam - Ectoderm development - small.pdf.


Take the Quiz

1

Ectoderm refers only to the neural plate region of the trilaminar embryo

true
false

2

The central nervous system forms in the sequence:

norochord to neural plate to neural tube
neural tube to neural plate to neural groove
neural plate to neural groove to neural tube
neural plate to neural crest to neural zone

3

The neural plate is narrower at the caudal (tail) end and therefore closes earlier than the broad cranial (head) end.

true
false

4

The correct sequence from cranial to caudal of the secondary brain vesicles is:

prosencephalon, mesencephalon, metencephalon, myelencephalon, rhombencephalon
telencephalon, diencephalon, metencephalon, mesencephalon, myelencephalon
telencephalon, diencephalon, mesencephalon, metencephalon, myelencephalon
prosencephalon, diencephalon, mesencephalon, myelencephalon, metencephalon


Internet Links

References

Textbooks

  • The Developing Human: Clinically Oriented Embryology (8th Edition) by Keith L. Moore and T.V.N Persaud - Mesoderm Ch15,16: p405-423, 426-430 Body Cavities Ch9: p174-184
  • Larsen’s Human Embryology by GC. Schoenwolf, SB. Bleyl, PR. Brauer and PH. Francis-West - Mesoderm Ch11 p311-339 Body Cavities Ch6 p127-146

Additional Textbooks

  • Before We Are Born (5th ed.) Moore and Persaud Ch16,17: p379-397, 399-405
  • Essentials of Human Embryology Larson Ch11 p207-228
  • Human Embryology Fitzgerald and Fitzgerald Body Cavities Ch5 p29-32, Ch7 p47,48
  • Human Embryology and Developmental Biology ?Carlson Ch9,10: p173-193, 209-222 Body Cavities Ch5 p29-32, Ch7 p47,48

Online Textbooks

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Reviews

  • Temporal dynamics of patterning by morphogen gradients. Kutejova E, Briscoe J, Kicheva A. Curr Opin Genet Dev. 2009 Jul 9. PMID: 19596567
  • The Hedgehog, TGF-beta/BMP and Wnt families of morphogens in axon guidance. Charron F, Tessier-Lavigne M. Adv Exp Med Biol. 2007;621:116-33. Review.

PMID: 18269215

  • Novel brain wiring functions for classical morphogens: a role as graded positional cues in axon guidance. Charron F, Tessier-Lavigne M. Development. 2005 May;132(10):2251-62. Review.

PMID: 15857918 | Development Link

Neural Development Terms

Only brief descriptions are given below, more complete definitions can be found in the glossary.

  • 3DMRI Three-dimensional magnetic resonance imaging. A new technique that allows 3D analysis of embryonic structures. (More? Prenatal Diagnosis - Magnetic Resonance Imaging)
  • 3rd ventricle a fluid-filled space formed from neural tube lumen, located within the diencephalon (from the primary vesicle prosencephalon, forebrain).
  • 4th ventricle a fluid-filled space formed from neural tube lumen, located within the rhombencephalon (from the primary vesicle, hindbrain).
  • adenohypophysis (anterior pituitary) = 3 parts pars distalis, pars intermedia, pars tuberalis.
  • alar plate afferent, dorsal horns
  • anlage (German = primordium, structure or cells which will form a future structure.
  • arachnoid - (G.) spider web-like
  • basal ganglia - (basal nuclei) neural structure derived from the secondary vesicle telencephalon (endbrain) structure from the earlier primary vesicle prosencephalon (forebrain)
  • basal plate efferent, ventral horns
  • brachial plexus mixed spinal nerves innervating the upper limb form a complex meshwork (crossing).
  • brain general term for the central nervous system formed from 3 primary vesicles.
  • buccopharyngeal membrane (=oral membrane) at cranial (mouth) end of gastrointestinal tract (GIT) where surface ectoderm and GIT endoderm meet. (see also [#cloacal membrane cloacal membrane])
  • cauda equina - (=horse's tail) caudal extension of the mature spinal cord.
  • central canal lumen, cavity of neural tube within the spinal cord. Space is continuous with ventricular system of the brain.
  • cerebral aqueduct ventricular cavity within the mesencephalon.
  • cervical flexure most caudal brain flexure (of 3) between spinal cord and rhompencephalon. ( sc-^V^ )
  • choroid plexus specialized vascular plexus responsible for secreting ventricular fluid that with further additions becomes cerebrospinal fluid (CSF).
  • cloacal membrane at caudal (anal) end of gastrointestinal tract (GIT) where surface ectoderm and GIT endoderm meet forms the openings for GIT, urinary, reproductive tracts. (see also buccopharyngeal membrane)
  • cortex - CNS structure derived from the secondary vesicle telencephalon (endbrain) from the earlier primary vesicle prosencephalon (forebrain).
  • cortical plate outer neural tube region which post-mitotic neuroblasts migrate too along radial glia to form adult cortical layers.
  • cranial flexure (=midbrain flexure) most cranial brain flexure (of 3) between mesencephalon and prosencephalon. ( sc-^V^ )
  • diencephalon the caudal portion of forebrain after it divides into 2 parts in the 5 secondary vesicle brain (week 5). (cavity- 3rd ventricle) Forms the thalmus and other nuclei in the adult brain. (sc-My-Met-Mes-Di-Tel)
  • dorsal root ganglia (=spinal ganglia) sensory ganglia derived from the neural crest lying laterally paired and dorsally to the spinal cord (in the embryo found ventral to the spinal cord). Connects centrally with the dorsal horn of the spinal cord.
  • dura mater- "tough" (Latin, mater = mother)
  • ectoderm the germ layer which form the nervous system from the neural tube and neural crest.
  • ependyma epithelia of remnant cells after neurons and glia have been generated and left the ventricular zone
  • floorplate early forming thin region of neural tube closest to the notochord.
  • ganglia (pl. of ganglion) specialized neural cluster.
  • glia supporting, non-neuronal cells of the nervous system. Generated from neuroepithelial stem cells in ventricular zone of neural tube. Form astrocytes, oligodendrocytes.
  • grey matter neural regions containing cell bodies (somas) of neurons. In the brain it is the outer layer, in the spinal cord it is inner layer. (see white matter white matter)
  • growth factor usually a protein or peptide that will bind a cell membrane receptor and then activates an intracellular signaling pathway. The function of the pathway will be to alter the cell directly or indirectly by changing gene expression. (eg shh)
  • hox (=homeobox) family of transcription factors that bind DNA and activate gene expression. Expression of different Hox genes along neural tube defines rostral-caudal axis and segmental levels.
  • hydrocephalus abnormality as the result of an imbalance between the rate at which the CSF is being formed and the rate at which the CSF is passing through the arachnoidal villi back into the blood (hydrocephalus rate is a function of the degree of imbalance in these two). Very small imbalance exhibit subtle, if any, symptoms. Large imbalances will have rapidly evolving symptoms of unmistakable import.
  • isthmus- (G. narrow passage)
  • lamina terminalis anterior region of brain where cranial neuropore closes.
  • lumbar plexus mixed spinal nerves innervating the lower limb form a complex meshwork (crossing).
  • mantle layer layer of cells generated by first neuroblasts migrating from the ventricular zone of the neural tube. Layers are rearranged during development of the brain and spinal cord. (Ven-Man-Mar-CP)
  • marginal zone layer of processes from neuroblasts in mantle layer. (Ven-Man-Mar-CP)
  • mater (Latin, mater = mother)
  • meninges mesenchyme surrounding neural tube forms 3 layer (Dura-, pia-, arachnoid- mater) connective tissue sheath of nervous system. (D-P-A-cns)
  • mesencephalon (=midbrain), the middle portion of the 3 primary vesicle brain (week 4). (sc-R-M-P)
  • metencephalon the cranial portion of hindbrain after it divides into 2 parts in the 5 secondary vesicle brain (week 5). Forms the pons and cerebellum in the adult brain. (sc-My-Met-Mes-Di-Tel)
  • myelencephalon the caudal portion of hindbrain after it divides into 2 parts in the 5 secondary vesicle brain (week 5). Forms the medulla in the adult brain. (sc-My-Met-Mes-Di-Tel)
  • neural tube neural plate region of ectoderm pinched off to form hollow ectodermal tube above notochord in mesoderm.
  • neural tube defect (NTD) any developmental abnormality that affects neural tube development. Commonly failure of neural tube closure.
  • neuroblast undifferentiated neuron found in ventricular layer of neural tube.
  • neurohypophysis (=posterior pituitary=pas nervosa)
  • neuron The cellur "unit" of the nervous system, transmitting signals between neurons and other cells. The post-mitotic cells generated from neuroepithelial stem cells (neuroblasts) in ventricular zone of neural tube.
  • neuropore opening at either end of neural tube: cranial=rostral=anterior, caudal=posterior. The cranial neuropore closes (day 25) approx. 2 days (human) before caudal.
  • notochord rod of cells lying in mesoderm layer ventral to the neural tube, induces neural tube and secretes sonic hedgehog which "ventralizes" the neural tube.
  • olfactory bulb (=cranial nerve I, CN I) bipolar neurons from nasal epithelium project axons through cribiform palate into olfactory bulb of the brain.
  • optic cup-
  • optic nerve (=cranial nerve II, CN II) retinal ganglion neurons project from the retina as a tract into the brain (at the level of the diencephalon).
  • otocyst (=otic vesicle) sensory [#placode placode] which sinks into mesoderm to form spherical vesicle (stage 13/14 embryo) that will form components of the inner ear.
  • pars (L. part of)
  • pharyngeal arches (=branchial arches, Gk. gill) form structures of the head. Six arches form but only 4 form any structures. Each arch has a pouch, membrane and cleft.
  • pharynx uppermost end of GIT, beginning at the buccopharyngeal membrane and at the level of the pharyngeal arches.
  • pia mater-
  • placode specialized regions of ectoderm which form components of the sensory apparatus.
  • pontine flexure middle brain flexure (of 3) between cervical and cranial flexure in opposite direction, also generates thin roof of rhombencephalon and divides it into myelencephalon and metencephalon. ( sc-^V^ )
  • prosencephalon (=forebrain), the most cranial portion of the 3 primary vesicle brain (week 4). (sc-R-M-P)
  • Rathke's pouch a portion of the roof of the pharynx pushes upward towards the floor of the brain forming the anterior pituirary (adenohypophysis, pars distalis, pars tuberalis pars intermedia). Where it meets a portion of the brain pushing downward forming the posterior pituitary (neurohypophysis, pars nervosa). Rathke's pouch eventually looses its connection with the pharynx. (Martin Heinrich Rathke 1973-1860, embryologist and anatomist)
  • rhombencephalon (=hindbrain), the most caudal portion of the 3 primary vesicle brain (week 4). (sc-R-M-P)
  • roofplate early forming thin region of neural tube closest to the overlying ectoderm.
  • spinal cord caudal end of neural tube that does not contribute to brain. Note: the process of secondary neuralation contributes the caudal end of the spinal cord.
  • spinal ganglia (=dorsal root ganglia, drg) sensory ganglia derived from the neural crest lying laterally paired and dorsally to the spinal cord (in the embryo found ventral to the spinal cord). Connects centrally with the dorsal horn of the spinal cord.
  • spinal nerve mixed nerve (motor and sensory) arising as latera pairs at each vertebral segmental level.
  • sonic hedgehog (=shh) secreted growth factor that binds patched (ptc) receptor on cell membrane. SHH function is different for different tissues in the embryo. In the nervous system, it is secreted by the notochord, ventralizes the neural tube, inducing the floor plate and motor neurons.
  • sulcus (L. furrow) groove
  • sulcus limitans longitudinal lateral groove in neural tube approx. midway between roofplate and floorplate. Groove divides alar (dorsal) and basal (ventral) plate regions.
  • sympathetic ganglia-
  • telencephalon the cranial portion of forebrain after it divides into 2 parts in the 5 secondary vesicle brain (week 5). (cavity- lateral ventricles and some of 3rd ventricle) Forms the cerebral hemispheres in the adult brain. (sc-My-Met-Mes-Di-Tel)
  • thalamus (G. thalamos= bedchamber) cns nucleus, lateral to 3rd ventricle, paired (pl thalami).
  • transcription factor a factor (protein or protein with steroid) that binds to DNA to alter gene expression, usually to activate. (eg steroid hormone+receptor, Retinoic acid+Receptor, Hox, Pax, Lim, Nkx-2.2)
  • trigeminal ganglion (=cranial nerve V, CN V) first arch ganglion, very large and has 3 portions.
  • vagal ganglion- (=cranial nerve X, CN X) fourth and sixth arch ganglion, innervates the viscera and heart.
  • ventricles the fluid-filled interconnected cavity system with the brain. Fluid (cerebrospinal fluid, CSF) is generated by the specialized vascular network, the choroid plexus. The ventricles are directly connected to the spinal canal (within the spinal cord).
  • ventricular zone Neuroepithelial cell layer of neural tube closest to lumen. Neuroepithelial cells generate neurons, glia and ependymal cells. (Ven-Man-Mar-CP)
  • vestibulocochlear nerve (=cranial nerve VIII, CN VIII, also called statoacoustic)
  • white matter - neural regions containing processes (axons) of neurons. In the brain it is the inner layer, in the spinal cord it is outer layer. (see grey matter)