PBL Topic 3 Case 1 Flashcards
What is gastrulation?
- The process that establishes all three germ layers in the embryo
Identify the three germ layers in the embryo and what they form.
- Ectoderm: nervous system
- Mesoderm, cardiovascular system, renal system, spleen
- Endoderm, GI tract and epithelia of respiratory systme
Where is the primitive streak located and when is it visible?
- Surface of the epiblast
- Day 15/16
What is invagination?
- Epiblast cells move towards primitive streak
- They become flask-shaped, detached from the epiblast
- They slip beneath the epiblast
Describe the molecular regulation of gastrulation.
- Fibroblast Growth Factor 8
- Which down-regulates E-cadherin between epiblast cells
Which cranial nerves does the ectodermal germ layer give rise to?
- Vagus nerve (10)
- Glossopharyngeal (9)
- Vestibulocochlear (7)
- Trigeminal (5)
- 1975
Describe the molecular regulation of neural plate formation.
- Fibroblast Growth Factor
- Which upregulates chordin and noggin
- Which inhibits Bone Morphogenetic Protein
- Which allows ectoderm to become neural tissue
Describe the process of neurulation.
- Lateral edges of neural plate become elevated to form neural folds
- Depressed mid-region forms the neural groove
- Neural folds approach each other in the midline
What is the function of neuropores during neurulation?
- Allow neural tube to communicate with amniotic cavity until neurulation is complete
On which days do the anterior and posterior neuropores close?
- Anterior: day 25
- Posterior: day 28
Identify the transition that neural crest cells undergo
- Epithelial to mesenchymal
- Mesenchyme refers to embryonic connective tissue regardless of origin
Identify the two pathways of neural crest cells.
- Dorsal pathway: to form melanocytes and hair follicles
- Ventral pathway: neurons, Schwann cells and cells of the adrenal medulal
Describe the molecular regulation of neural crest cells.
- Intermediate levels of BMP
- Which induce transcription factors
- PAX3, SNAIL, FOXD3 are responsible for specification
- SLUG which promotes migration
Identify the embryological origin of the structures of hearing and equilibrium
- Otic placodes
Identify the embryological origin of the structures sight
- Lens placodes
Name the three primary brain vesicles and what they refer to.
- Prosencephalon - forebrain
- Mesencephalon -midbrain
- Rhombencephalon - hindbrain
Where is the cervical flexure located?
- At the junction between the hindbrain and spinal cord
Where is the cephalic flexure located?
- In the midbrain region
Identify the two portions of the prosencephalon
- Telencephalon
- Diencephalon
Identify the two portions of the rhombencephalon and how are these two structures separated?
- Metencephalon
- Myelencephalon
- Pontine flexure
Identify the ventricles of the brain
- Cerebral hemispheres are lateral ventricles
- Diencephalon is third ventricle
- Rhombencephalon is fourth ventricle
How are the third and fourth ventricles connected?
- Cerebral aqueduct
How are the lateral ventricles connected to the third ventricle?
- Interventricular foramina of Monroe
Where are neuroepithelial cells located?
- The walls of the recently closed neural tube