Lecture 3 ADD FLASHCARDS

What is the most complex organ in the body characterized by a diversity of cell types?

The nervous system (Nervensystem)

What does the term neurogenesis (Neurogenese) describe?

The generation of nerve cells that generally do not divide again for the rest of life

What is the term for cells that have finished dividing?

Postmitotic (postmitotisch)

Why are diseases that attack nerve cells particularly severe?

Because nerve cells are generally only generated once during development and cannot be replaced

What process occurs once a cell becomes postmitotic and begins growing processes?

Axogenesis (Axogenese)

What is the process of an axon finding its target area?

Pathfinding (Wegfindung)

What is the formation of connections once a target area is reached?

Synaptogenesis (Synaptogenese)

Which historical method developed by Camillo Golgi randomly stains approximately every tenth nerve cell?

The Golgi method (Golgi-Methode)

What do nerve cells receive during development that tells them their identity and target area?

A package of genetic information (genetisch programmiert)

At which early embryonic stage does the study of nervous system generation begin?

The blastula stage (Blastula-Stadium)

What are the three germ layers (Keimblaetter) distinguishable in the blastula?

Ectoderm (Ektoderm), mesoderm (Mesoderm), and endoderm (Endoderm)

Which germ layer (Keimblatt) gives rise to the future epidermis and the nervous system?

The ectoderm (Ektoderm)

What does ecto mean?

Outside (aussen)

Which germ layer (Keimblatt) acts as the organizer and forms muscles?

The mesoderm (Mesoderm)

What does meso mean?

Middle (mittel)

Which germ layer (Keimblatt) forms internal organs and is not relevant for the nervous system?

The endoderm (Endoderm)

What does endo mean?

Inside (innen)

What is a fake map (Scheinkarte) or fate map (Schicksalskarte) in embryology?

A predictable pattern of what cell groups will normally become if there is no intervention

What is the process of invagination (Einstuelpung) following the blastula stage?

Gastrulation (Gastrulation)

What is the specific site of invagination during gastrulation?

The blastopore lip (Blastoporen-lippe)

Which germ layer is moved from the outside to the inside during gastrulation?

The mesoderm (Mesoderm)

What structure is present at the end of gastrulation as a precursor to the nervous system?

The neural plate (Neuralplatte)

Who performed the famous transplantation experiments to find the nervous system inducer?

Mangold and Spemann

What specific region did Mangold and Spemann transplant?

The organizer (Organisator) region located directly above the blastopore lip

What was the result of transplanting the organizer to the ventral side of another embryo?

The induction (Induktion) of a second embryonic axis (embryonalen Achse) or neural plate

In the Mangold and Spemann experiment, what tissue did the second nervous system mostly consist of?

Recipient tissue (Empfaenger-gewebe), which was pigmented

Which structure in the induced second axis was made of donor cells?

The notochord (Notochord)

What is the definition of induction (Induktion)?

When one tissue influences the development of surrounding tissue into a different cell fate

What is the chick equivalent of the organizer (Organisator) called?

Hensen s node (Hensens-Knoten)

What is a signal center (Signalzentrum)?

A region like the organizer that secretes molecules to direct development

What are the two criteria for a molecule to be considered an in vivo inducer?

It must be sufficient to induce the tissue alone and must be expressed in the organizer region

What is the correct model for neural induction in the ectoderm?

Inhibition (Inhibierung) of a default pathway that would otherwise form epidermis

Which family of activating ligands normally signals ectoderm to become epidermis?

TGF-beta family, specifically BMPs (Bone Morphogenetic Proteins) and activin

What type of intracellular activity do TGF-beta receptors have?

Cytoplasmic threonine serine kinase activity (zytoplasmatischer Thr/Ser Kinase Aktivitaet)

What happens to the neural pathway when the TGF-beta receptor is activated?

The neural pathway is blocked (geblockt)

Which three molecules act as inhibitors (Inhibitoren) for TGF-beta ligands to allow neural tissue to form?

Noggin, follistatin, and chordin

Where are noggin, follistatin, and chordin expressed?

In the signal center (Signalzentrum) such as the organizer or Hensen s node

What form is chordin specifically found in when expressed in the signal center?

mRNA (Chordin-mRNA)

What is the process where the neural plate folds and closes to move inside the body?

Neurulation (Neurulation)

What structures rise and fuse during neurulation?

Neural folds (Neuralfalten)

What is the resulting closed structure from neurulation?

The neural tube (Neuralrohr)

What medical condition results if neurulation (Einstuelpung) fails to happen correctly?

Spina bifida

What coordinates must be established for pattern formation (Musterbildung) in the NS?

Anterior-posterior, dorsal-ventral, and mediolateral

What method is used to create a fate map (Schicksalskarte) during the neural plate stage?

Cell marking with dye (Zellmarkierung mittels Farbstoff)

Are cells in the neural plate stage already postmitotic?

No, they are still dividing but their future fate is already predictable

What is the anterior-most part of the brain that splits into the telencephalon and diencephalon?

The prosencephalon (Vorderhirn)

What are the two divisions of the prosencephalon?

The telencephalon (Endhirn) and the diencephalon (Zwischenhirn)

What is the middle brain region called?

The mesencephalon (Mittelhirn)

What is the hindbrain region that is segmented into rhombomeres?

The rhombencephalon (Rautenhirn)

How many rhombomeres (Rhombomere) are there typically in the hindbrain?

Eight (r1-r8)

What is the posterior-most part of the central nervous system?

The spinal cord (Rueckenmark)

Which mesodermal structure lies ventral to the neural tube and acts as a signal source?

The notochord (Notochord)

Which signal molecule is expressed ventrally in the notochord and floor plate?

Sonic hedgehog (shh)

Which signal molecule is expressed dorsally?

Wnt1

Which signal molecule is found at the mid-hindbrain junction?

Fibroblast growth factor 8 (FGF8)

How do cells know their identity based on signal sources?

They measure the concentrations of extracellular signals (Signalquellen)

Which gene family is highly organized and conserved for patterning the rhombomeres?

Hox genes (Hox-Gene)

What is the principle where genes are arranged on the chromosome in the same order they are expressed in the body?

Colinearity (Kolinearitaet)

How does each rhombomere (Rhombomer) get its specific identity?

Through a specific combination (Kombination) of hox genes

How do rhombomeres maintain sharp boundaries?

Through differential cell adhesion (Zelladhaesion) and affinity

What is the innervation of muscles in segments along the body called?

Segmental innervation (segmentale Innervation)

Why is the level of a spinal cord injury critical?

Because higher injuries sever the communication for all segments below them

Which motor column innervates axial musculature for posture?

The medial motor column (MMC)

Which motor column is specifically found in the brachial and lumbar regions to innervate limbs?

The lateral motor column (LMC)

What are the three signal sources for dorsal-ventral patterning in the spinal cord?

Notochord, floorplate (Bodenplatte), and roofplate (Dachplatte)

Where is the floorplate (Bodenplatte) located?

Directly dorsal of the notochord, at the ventral base of the neural tube

Is the floorplate (Bodenplatte) made of neural tissue?

No, it is a non-neural signal source

Where is the roofplate (Dachplatte) located?

At the dorsal top of the neural tube

What is the ventral morphogen in the spinal cord?

Sonic hedgehog (shh)

What are the dorsal morphogens in the spinal cord?

BMPs (Bone Morphogenetic Proteins)

What is a diffusible signal that affects cell fates based on concentration thresholds?

A morphogen (Morphogen)

What are concentration thresholds (Schwellenwerte der Konzentration)?

Specific levels of a signal required to trigger a specific cell identity

Which cell type is induced by the highest concentration (4nM) of shh?

V3 interneurons (V3-Interneuronen)

Which cell type is induced by 3nM of shh?

Motor neurons (Motoneuronen)

Which cell type is induced by 2nM of shh?

V2 interneurons (V2-Interneuronen)

What happens to ventral neural tube cells if no shh is present?

They all become V0 cells

Which molecules are used as markers to distinguish different neurons in an induction assay?

Transcription factors (Transkriptionsfaktoren)

Is brain patterning similar to spinal cord patterning?

Yes, it uses similar principles and signal sources like FGF8 and Wnt3a

What is conserved between species regarding cortical maps?

The general topography (Topographie), though sizes of regions vary

Where is the visual cortex (visueller Kortex) located in both mice and humans?

The posterior region

What is the generation of neurons in the cortex called?

Cortical neurogenesis (kortikale Neurogenese)

What is the zone where progenitor cells (Vorlaeuferzellen) divide?

The ventricular zone (ventrikulaere Zone - VZ)

What happens to neurons once they become postmitotic in the cortex?

They migrate (migrieren) out of the ventricular zone

What is the zone containing axons from the thalamus and early cortical neurons?

The intermediate zone (IZ)

What is the first group of generated postmitotic neurons called?

The preplate (PP)

What structure splits the preplate into the subplate (SP) and the marginal zone (MZ)?

The cortical plate (CP)

What type of migration describes younger neurons moving past older ones to the outside?

Inside-out migration (Inside-out-Migration)

Which cells act as the scaffolding for neuronal migration in the cortex?

Radial glia cells (radiale Gliazellen)

Which group of cells migrates from above the roofplate to form ganglia and skin pigment?

The neural crest (Neural-leiste)

What are the three main fates of neural crest (Neural-leiste) cells?

Sympathetic ganglia, sensory ganglia (DRG), and melanocytes (Melanozyten)

How do granule cells (Koernerzellen) in the cerebellum migrate compared to the cortex?

In the opposite direction, from the outside to the inside

Do new neurons generally form in the adult human cortex?

No, cortical neurogenesis is finished after development

Where is adult neurogenesis (Neurogenese) known to occur in some species?

The olfactory bulb (Riechkolben) and the hippocampus