Lecture 2 Flashcards
The blastocyst goes on to form the…
The inner cells become the embryo.
The outer cells become the accessory cells such as the placenta.
The inner cells (embryo) layers are the…
Epiblast and hypoblast.
What is the hypoblast?
Formed after gastrulation.
What is the epiblast?
Formed after gastrulation.
The outside cells interact with the ____ to form the ____.
Uterine lining to form the placenta.
What is gastrulation?
Cell movements that generate the three germ layers:
Endoderm
Mesoderm
Ectoderm
What is the endoderm?
The germ layer that becomes the gut and the viscera.
What is the mesoderm?
The germ layer that becomes the notochord, bone and muscle.
What is the ectoderm?
The germ layer that becomes the skin, hair and nervous system.
How is the mesoderm formed from the hypoblast and epiblast?
There is a movement of cells that go from the epiblast into the middle layers to form a third layer sitting in between that is called the mesoderm. Epiblast is now the ectoderm and hypoblast is now the endoderm.
What is neurulation?
The formation of the neural tube.
How does the neural tube form?
Ectodermal cells go towards the dorsal area of the organism then rise and form folds with a groove in between. This is called neurulation.
What is the neural tube?
A long tube that spans the entire organism. It later becomes the CNS.
Where is SHH produced?
The notochord and the floor plate.
What does SHH do?
Influences the patterning of the ventral part of the neural tube.
What is BMP?
Bone morphogenic protein.
Where is BMP produced?
In the dorsal part of the neural tube.
How is the gradient of patterning created?
By BMP and SHH interacting. It determines what the neurons become during development.
Neurons generated in the ventral part of the neural tube will become?
Motor neurons.
Neurons generated in the dorsal part of the neural tube will become?
Sensory neurons.
What is expressed in the dorsal part of the neural tube?
BMP
WNT
What type of neurons do the proteins affect?
BMP = sensory WNT = sensory SHH = motor
The neural tube gets more _____ as we go toward the ____ part of the animal.
more advanced as we go to the anterior part of the animal.
The rostral part of the neural tube develops into…
The telecephalon and the diencephalon (forebrain).
The mesenscephalon gives rise to the…
Midbrain.
The rhombencephalon gives rise to the…
Pons, medulla, cerebellum.
The telecephalon gives rise to the…
Hemispheres Cerebrum Hippocampus Olfactory bulb Basal ganglia
The diencephalon gives rise to the…
Hypothalamus (affect)
Thalamus (relay)
What is FGF?
Fibreglass growth factor.
How does the location in the brain affect the exposure to proteins?
There are higher concentrations in different areas of the brain which influences genes that determine whether a neuron is motor/sensory.
Where is FGF higher?
In the anterior part, decreases in the posterior part of cortex.
What happens when you inject FGF in various areas of the cortex?
You alter the spatial distribution of the cortical areas. When you create a secondary gradient, it duplicates the cortex.
How is the cortex developed?
Inside out.
Cells migrate radially.
First produced will be deeper layers. Latest will be external areas.
Why are the gyri and sulci produced?
Due to an overproduction of neurons on the outer (later) layers.
Inside out is also known as…
Radial migration. From ventrical to the outside.
Radial migration gives rise to which kind of neurons?
Excitatory neurons. In cortex.
Tangential migration gives rise to which kind of neurons?
Inhibitory neurons. In striatum.
Life of the inhibitory neuron.
Born in the striatum
Move tangentially
Follow the curvature of the brain
Life of the excitatory neuron.
Born in the cortex
Move radially
If early, inner. If later, outer.
Where is the growth cone?
It is the distal most part of the axon.
What does the growth cone do?
It guides the neuron.
The two most important structures in the growth cone are…
The microtubules and the actin filaments.
Microtubules are…
Tiny tubes that enable cell movements and organelle reorganisation.
Actin filaments are…
Little chains of proteins (pearl necklace)
Growth, retraction.
What is growth and reduction of the microtubules and actin filaments?
Polymerasing is growing.
Depolymerasing is cutting down.
What are attractants and repulsants?
Proteins that make the growth cone extend are attractants and those that make it retract are repulsants.
What are the mechanisms of growth cone guidance?
Matrix adhesion Cell surface adhesion Fasciculation Chemoattraction Contact inhibition Chemorepulsion
What is most important in the formation of the hemispheres/CC?
The prenatal glial cells. They use all mechanisms of growth cone guidance to guide the neurons, then they die before we are born.
What happens when calcium spikes are suppressed/increased?
Suppressed, more excitatory neurons.
Increased, more inhibitory neurons.
What happens when a neuron is silenced?
There is severe disruption in axonal branching. Not necessarily more or less, just disturbed.
What does electrical activity do to brain development?
It has an overall influence on circuit making. Not always decreasing/increasing but always affecting development.
How does dendritic growth work?
Soma only
Axon develops
Dendrites begin to extend and branch
Dendrites begin to make connections to other axons
Dendrites decrease and selective connections are reinforced
How does specificity work?
Motor neurons originally innervate many muscles but eventually innervate specific muscles.
Visual neurons originally receive input from various areas of the thalamus, go on to receive specific inputs.
More precision.
Can the negative effects of low socialisation be passed on to future generations?
Yes, the epigenetic effect can be passed on because pups will go on to be less maternal to their pups and so forth.
What to remember about hormones in development.
The hormones (test, est, pro) are produced by different activities of these enzymes and both males and females have these hormones.
Different levels are produced in different stages in development.
Can elicit growth in different areas, e.g. est eliciting growth in the hypothalamus.
What was the difference between the two types of prairie voles?
The monogamous ones expressed oxytocin in the basal ganglia.