Mcb 80 Lecture 18

Front 1

Neurulation

Back 1

the first step in neural development, when the organizer induces the body axis (in which the neural tube and the neural crest form, later to become the central and peripheral nervous systems, respectively).

Hint 1

A part of organogenesis in vertebrate embryos. The process begins when the notochord induces the formation of the central nervous system (CNS) by signaling the ectoderm germ layer above it to form the thick flat neural plate.
STEPS.
1. induction
2. Neural plate--> neural tube
3. Neural tube differentiates into
- spinal chord
- brain
- CNS

Front 2

Induction

Back 2

the organizer, a portion of the mesoderm that gives rise to the notochord, signals where cells will amass to form the neural tube and the neural crest, forming the axis of the body

Hint 2

The key step of neurulation which occurs when a portion of the mesoderm called "the organizer" gives rise to the notochord which in turn induces the neural tube.

Front 3

Positional information

Back 3

the position of a cell in an animal determines the identity it will acquire.

Me:
The idea that the position of a cell in an animal determines the identity it will acquire. A morphogen released from one end of the axis forms a gradient, and the concentration of morphogen determines which genes are activated. The pattern of gene expression, in turn, endows the cell (or tissue) with specific features.

Front 4

Apoptosis

Back 4

Short answer: programmed cell death, (in NS during which half of the neurons that have been generated die as development proceeds.)

Long Answer: A genetically regulated process, occurring in specific tissues during development and disease, by which a cell destroys itself; marked by the breakdown of most cell components and a series of well-defined morphological changes

Front 5

Nerve Growth Factor

Back 5

An attractant that is used to signal growth of axons

Front 6

Morphogen

Back 6

released during the early stages of development and forms a gradient along the body axis. The concentration of morphogen determines which genes are expressed in the cells in that region (regionalization)

Front 7

Stem Cell

Back 7

an undifferentiated cell that can become a cell of any type through specialization. Stem cells can divide to produce at least one daughter cell just like it or turn it into a more differentiated cell.

Front 8

Radial Glial Cell

Back 8

guide the locomotion of cells during the migration stage of development. They are long cells along which the principal neurons migrate radially.

Front 9

What are the 9 main steps in mammalian neural development?

Back 9

1. Neurulation
2. Regionalization
3. Neurogenesis
4. Migration
5. Differentiation
6. Programmed Cell Death
7. Axon Guidance
8. Synapse Formation
9. Synaptic Rearrangement

Front 10

What are the 3 primary cell layers of the early embryo and from which does the nervous system arise?

Back 10

Ectoderm, Mesoderm, and Endoderm. The nervous system arises from the ectoderm. Not to be confused with ecto-cooler.

Front 11

Describe or draw the way in which the neural plate, neural fold, neural tube and neural crest arise?

Back 11

An area of the ectoderm becomes the neural plate as a result of morphogens released by the organizer which is part of the mesoderm. The neural plate then becomes the neural groove en route to forming the neural tube; and the regions of ectoderm adjacent to it become neural folds before they join together and then split inside of the ectoderm as neural crest. See slide 4 for visual.

Front 12

What was the Spemann/Mangold organizer experiment and why was it important?

Back 12

They took an organizer from a pigmented embryo and transplanted it into an unpigmented embryo where it induced the creation of a second neural tube. This is important becuase it provides insight into how the neural tube arises.

Front 13

How do cortical projection neurons migrate to their destinations? (Where do they arise, where do they go, and what guides do they use?)

Back 13

Principal neurons(ones that send axons out of the cortex) migrate radially from the the ventricular zone along radial glia. Interneurons migrate "tangentally" from subcortical areas.

Front 14

What is the relationship of birth-order to laminar position for cortical neurons?

Back 14

The first born neurons are arranged closed to the ventricular zone, with later neurons migrating farther away essentially making the birth order and laminar position inside out.

Front 15

What is the trophic hypothesis for neuronal survival?

Back 15

If the target affects survival (not production or differentiation) of neurons and neuron number is proportional to target size then the trophic hypothesis posits that the target secretes a limited amount of a "neurotrophic" molecule needed for survival (essentially allowing for a limited number of neurons)

Front 16

What is one piece of evidence that neurons depend on their targets for survival?

Back 16

When the synaptic target of a neuronal type is removed during development, the amount of neuronal death increases.