Lecture 21. Organogenesis Flashcards
(73 cards)
What is neurulation ?
A special type of organogenesis, where it sets cells aside and forms the entire nervous system
Where does the nervous system arise from ?
The ectoderm
Where does the somites and the heart arise from ?
The mesoderm
Where does the lungs arise from ?
The endoderm
What is organogenesis ?
The interaction of cells within and across the germ layers to form organ systems
What is organogenesis characterised by ?
Local interactions superimposed on the information laid down with the basic body plan, to allow definition and development of an organ
What does organogenesis involve ?
The interaction and rearrangement of cells to produce tissues and organs
How does neurulation begin ?
As cells from the dorsal mesoderm form the notochord
What causes the ectoderm to form the neural plate ?
Signalling molecules secreted by the notochord and other tissues
What processes cause the formation of the neural plate ?
Induction using sonic the hedgehog
What happens as the neural folds and fuse ?
The adjacent surface ectoderm fuses to enclose the neural tube which becomes the brain and spinal cord
What happens after the neural tube forms ?
Neural crest cells migrate away from the dorsal aspect of the tube to peripheral locations where they give rise to the peripheral nervous system
What are neural crests cells formed by ?
Interactions between surface and neural ectoderm
How do neural crest cells form the peripheral nervous system ?
They migrate away from the dorsal midline as the neural folds fuse
What is the peripheral nervous system made up of ?
- The sensory system and motor system
2. Autonomic nervous system
What is neurulation ?
Signalling from the notochord, using Shh which also influences the type of neuron that differentiates along the dorso-ventral axis
What is neurogenesis ?
The formation of the central nervous system
What is the choice of forming a neuron or glial cell specified by ?
Delta notch signalling pathway
What does the activation of delta notch pathway equal ?
Differentiation of neuron
What does the hox code act as ?
Operated to provide positional information along the anterior posterior axis of the central nervous system
What are somites ?
Mesoderms cells that form into blocks on either side of the neural tube
What type of structures are somites ?
Transitionary structures that later form muscle blocks of the body and limbs and the vertebrate of the back bone
Where does regionalisation of the mesoderm germ layer occur ?
From the center midline:
- Notochord
- Somites
- Intermediate mesoderm - kidney, gonads
- Lateral plate mesoderm
What does the lateral plate mesoderm split into ?
Splits into two divided by a coelom cavity
