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20 Cards in this Set

  • Front
  • Back
Bilaminar Disc - what is hypoblast, epiblast, and primitive streak
-Epiblast is floor of amniotic cavity
-Hypoblast is roof of yolk sac
-The two epithelial layers are sandwiched
-Primitive Streak forms as mid-line invagination depression in epiblast
Consequences of Formation of Primitive Streak/Node - what 2 things does it establish and and what 3 processes does it serve as a site for
-Establishes axis of bilateral symmetry
-Establishes head and tail end
-Serves as site for invagination, migration, and differentiation of epiblast cells to establish three primary germ layers
What are the 3 epiblast derivatives
Notochord Formation - formed where, by what, extends in what direction, lies along what part
-In primitive node, some epiblast cells invaginate to become mid-line mesoderm
-This Notochord extends cranially as primitive node regresses caudally
-Lies along mid-line axis of body, along axis of bilateral symmetry, just deep to neural plate, between somites
Notochord Fate - plays a role in what?, forms what?, what happens to a portion in the vertebral bodies?, what happens to a portion in intervertebral discs?
-Plays role in INDUCTION of neural plate in overlying ectoderm
-Forms transient CT rod beneath neural plate and between somites.
-Portion in vertebral bodies converted to bone
Portion in intervertebral discs persists as NUCLEUS PULPOSUS
vertebrate embryo, somites (or primitive segments in older texts) are masses of mesoderm distributed along the two sides of the neural tube and that will eventually become dermis (dermatome), skeletal muscle (myotome), and vertebrae (sclerotome).
Consequnces of Gastrulation (3)
1)CNS inducer in place
2)Three primary germ layers established
a)Ectoderm forms outer surface and CNS
b)Mesoderm forms CT, muscle, CV system, UG system
c)Endoderm forms lining of gut tube
3)Basic body plan begins to unfold
Ectoderm - which layer is it, and forms what (3)
-Outermost (most superficial) layer
-Forms what you see in Mirror, CNS, and Neural Crest derivatives
Mesoderm - which layer is it, forms what
-Middle layer
-Most muscles, bones, ligaments, fasciae, etc.
-Most CTs, CVS, blood and bone marrow, wall of GI and UG system
Endoderm - which layer is it, forms what, innervated by what
-Forms Innermost Layer
-Forms Epithelium Lining Gut Tube and its Diverticula only
-CT and muscle of wall comes from sphlanchnic mesoderm
-Innervation comes from neural crest
3 Germ Layers vs. 4 Tissue Types
Which germ layer can epithelium come from, Mesothelium and Endothelium are derivatives of what
Ectoderm, mesoderm, and endoderm are 3 primary germ layers
Epithelium, nervous, CT, and muscle are 4 tissue types
No necessary connection between names
Epithelium can come from all three primary germ layers
Mesothelium and Endothelium are both mesodermal derivatives
Many organs have derivatives from which germ layer? Name where the esophagus is derived from
-Many organs have derivatives from more than one primary germ layer.
-Esophagus has luminal lining from Endoderm, mural smooth muscle from splanchnic Mesoderm, and innervation from Ectoderm (via neural crest).
Early Development of CNS (4)
1) In early development, deep tissues beneath superficial layer on outer surface of embryo induce formation of mid-line Neural Plate
2) Neural plate expanded in cranial part - becomes Brain
3) Neural plate narrow in caudal part - become Spinal Cord
4) Neural plate folds up into neural tube - Neural Crest leaves neuroepithelium - neural tubes sinks beneath surface of body
Neuroepithelium - type of epithelium, cells found in it, what these cells turn into (2) and then what they differentiate into
-Primitive neural tube consists of a highly proliferative, PSEUDOSTRATIFIED EPITHELIUM
-STEM CELLS divide rapidly by mitosis, one daughter cell differentiates, other continues to divide
-Some stem cells form NEUROBLASTS, which differentiate into neurons
-Other stem cells form GLIOBLASTS, which differentiate into glia
Wall of Neural Tube Thickens - How? Thickening in spinal cord vs. thickening in brain
-By repeated MITOSES of stem cells, thickness of neuroepithelium increases dramatically
-Thickening is large in spinal cord
-Thickening is even larger in brain
Development of Brain I - Cranial End of Neural Tube forms what 4 structures and Caudal end of Neural Tube forms what 1 structure. Which end grows more rapidly?
-Cranial end of neural tube grows more rapidly than caudal end
-Cranial end forms BRAIN
-Caudal end forms SPINAL CORD
-Cranial end forms three primary brain vesicles, Prosencephalon (forebrain), Mesencephalon (midbrain), and Rhombencephalon (hindbrain)
Development of Brain II - Prosencephalon forms what 2 structures, Mesencephalon forms what structure(s), Rhombencephalon forms what 2 structures
-Prosencephalon forms Diencephalon and Telencephalon (both together form brain)
-Mesencephalon remains primitive (forms brainstem)
-Rhombencephalon forms Metencephalon and Myelencephalon (both together form cerebellum)
Neural Tube Defects (NTDs) - Caused by what (2), symptoms range from what
-Common kind of congenital birth defects
-Typically caused by failure of neural tube closure and/or induction of bony neural arches of spinal cord
-Range in severity from asymptomatic spina bifida occulta to devastating and fatal anencephaly
Etiology of NTDs - what type of etiology, incidence rates in different ethnicities
-Multifactorial etiology- some genetic and some environmental- difficult to sort out
-Higher incidence among Irish in Dublin
-Slightly lower incidence in Irish-Americans in Boston
Low incidence in African Americans
Alpha-fetoprotein (AFP) and NTDs - AFP produced where and enters where, role of NTDs in terms of AFP, screening for Maternal serum-alpha-fetoprotein (MSAFP), visible on what type of graphy
-Alpha-fetoprotein (AFP)- A prenatal test to measure the amount of a fetal protein in the mother's blood; produced in liver but enters CSF
-NTDs lead to increased AFP in amniotic fluid and maternal serum
-Screening for MSAFP (blood test for certain fetal disorders) can lead to increased detection of NTDs
-Visible on ultrasonography