Exam 3- Neural and Neural Crest Development Flashcards
What happens week 3, week 4, and week 4-6 during the first trimester?
Week 3: neurulation- formation of the brain and spinal cord from the ectoderm.
Week 4: Neural Crest Migration- from the neural tube into the face
Week 4-6: Nerve Innervation of the Face- Cells from neural crest and placode form bases of peripheral nervous system.
During week 3 of the first trimester, the nervous system forms from the _______ during gatrulation, which is divided into what 2 territories?
ectoderm
1) Neural Plate- compromises of columnar epithelium; becomes brain/ spinal cord
2) Lateral Ectoderm- cuboidal epithelium; becomes epidermis of skin
T/F: The neural plate is induced to form from the ectoderm by signals from the node and from the underlying notochord during gastrulation.
This induction also establishes the disto-caudal axis of the future central nervous system.
False; rostro-caudal axis
Neurulation: formation of the neural tube….
- After neural induction, the neural plate forms the bilateral ______, which move toward the midline and fuse, to form the_______ .
- Fusion begins at the cervical region, and proceeds both cranially and caudally. Cranial and caudal ______ close at day 25 and 27, respectively.
- Once fusion is complete, the neural tube is covered dorsally by ___________.
- The anterior tube gives rise to the _____, while the posterior portion becomes the ______.
neural folds; neural tube
neuropores
ectodermal epidermis
brain; spinal cord
What are five steps of neurulation (formation of the neural tube)?
1) Shaping- of the epidermal sheet, which contains a neural crest (stem cells)
2) Folding- forms a median hinge ponit
3) Elevation- of neural folds
4) Convergence- of the dorsal lateral hinge point together
5) Closure- closures of the DLH point, forming the epidermis
What’s the difference between primary neurulation and secondary neurulation?
Primary neurulation involves formation of neural tubes
Secondary neurulation is formation of the neural tube at tail end
Secondary Neurulation: formation of neural tube at tail bud-
Regressed primitive streak forms cell mass called the ______, whose central cells are condensed to give rise to the ________. Afterwards, the _____ after cavitation merges with neural tube
tail bud; medullary cord; Medullary cord
What’s the difference between the primary and secondary neurulation in terms of steps to get to a completed neural tube?
primary- EPITHELIUM; involves initial epithelium, which columinizes, rolls/ folds and closes into the neural tube
Secondary- MESENCHYME; involves initial mesenchyme, which condenses into a medullary cord/ neural rod and then transitions/ cavitates into a neural tube
Wnt, BMP, Shh, & FGF…. what are they responsible for?
Wnt/ BMP- secreted by ectoderm (WEB); required for dorsal neural tube and neural crest development
Shh- secreted by notochord; induces ventral neural tube fates (i.e. Motor neuron)
FGF- expressed by somites; provides additional patterning information
The internalized _______ expands and differentiates along its length to form discrete brain regions and the spinal cord
neural tube
What brain regions does the neural tube expand/ differentiates into? (3)
forebrain, midbrain, and hindbrain
NOTE- also differentiates/ expands into spinal cord
The neural tube expands and differentiates into the forebrain, hindbrain and midbrain. What are there components?
Forebrain: telecephelon + Diencephalon
Midbrain: mesencephalon
Hindbrain: metacephalon + myelencephalon
What is spina bifida and anencephaly? How does it occur?
Failures in neural tube closure vary
SB- incpmlete neural closure- trunk level
A- incomplete neural tube closure- cranial level
NOTE- Diet: folic acid added to diet to prevent this
What happens during week 4 of the first trimester?
neural crest migration: from the neural tube into the face
What becomes the neural crest?
the ectoderm-neural tube border, that forms when the ectoderm closes over the neural tube as it forms
Epithelial cells at the dorsal neural tube become mesenchymal and thus are able to migrate. Which signals tells the cells to become migrating neural crest cells? (3)
Wnt, FGF & BMP
Epithelial cells at the dorsal neural tube become mesenchymal and thus are able to migrate. Initially, epithelial cells are connected by _____ and are _____. However, they lose these properties and they become mesenchymal.
tight junctions; polarized
Hindbrain and caudal midbrain neural crest cells migrate into the ______, while and anterior midbrain and forebrain crest cells migrates to ______.
pharyngeal arches; forebrain regions
Neural crest cells from particular ______ always contribute to a select pharyngeal arch. R1/R2 migrate to arch ____, R4 migrate to arch ___ and R6/R7 migrate to arch ____. These are controlled by _______.
rhombomeres; arch 1, arche 2, arch 3; HOX genes
The ______ form as fingers around the anterior expansion of the gut tube, the pharynx, and lie ventral to the developing _______. They are created by proliferation of _______, which is derived from mesoderm and neural crest.
pharyngeal arches; neural tube; mesenchyme
The pharyngeal arges develop as outpocket fingers due to proliferation neural crest cells. The form around the anterior expansion of the ______ and ventral to the ______.
gut tube; neural tube
Holoprosencephalies-midline defects, Otocephalies, Retinoic acid Syndrome, DiGeorge Syndrome, Hemifacial Microsomia and Treacher Collins syndrome are all caused by what?
Abberant arch development/ neural crest defect
Neural Crest Syndrom: Holoprosencephalies- what two things causes it
- midline defects caused by Shh, ethanol and excess vitamin A
- caused by defects in forebrain patterning, resulting in flat nose, hypotelorism and microcephaly
Neural Crest Syndrom: Reinoic Acid Syndrom
- Retinoic-Vitamin A derivative caused severe abnormalities of external and middle ear, cleft palate, cardiovascular defects, etc.
- Caused by inability to clear retinoic acid metabolites
- Migration of NCC into first and second arch (facial) and into the third and forth arch (cardiovascular) affected
- Caused from cell death
NOTE: NCC= neural crest cell
What happens during week 4-6 of the first trimester?
Nerve innervation of the face: Cells from neural crest and placode form bases of peripheral nervous system.
What’s difference between oligodendrocytes and Schwann Cell?
O- the insulation of the axons exclusively in the CNS (CONS)
SC- insulation of axons in the PNS (pnS)
_____ provide support and myelinate cells to increase conduction of signal.
Glia (i.e. Schwann Cells/ Oligodondrocytes)
Cranial nerves: 12 most of which are ganglionated, i.e., has aggregates of sensory neurons outside the brain:
1) _______: Trigeminal (V) & Facial (geniculate; VII)
2) ______: Glosspharyngeal-superior and interior/ petrosal; vagal-jugular and nodose
3) _______: occulomotor (III), facial (geniculate, VII) & glossopharyngeal (IX)
4) _______: cervical chain ganglia
1) Sensory: single ganglia
2) Proximal (p) and distal (d) ganglia
3) parasympathetic
4) sympathetic
Proximal sensory neurons arise from _____, and distal neurons arise from ______.
neural crest; placodes
Proximal sensory neurons arise from neural crest, and distal neurons arise from placodes. What cranial nerves do they fuse into?
Placodal and neural crest-derived neurons fuse into a single ganglion for cranial nerves V and VII (mostly), but remain as distinct proximal and distal ganglia for cranial nerves IX and X.
Which 4 cranial nerves allows for digastric jaw movement?
Trigeminal (V), Facial (VII), glossopharyngeal (IX) & Vagus (X)
The Trigeminal Ganglia (V) innervate the _______ nerves in the maxilla and the ________ nerves in the mandible.
Superior Alveolar Nerves; Inferior Alveolar Nerves
The trigeminal ganglia (V) innervates thre mandible through the Inferior Alveolar Nerve- tracks through the mandible through foramina. 2 IA nerves are:
1) ______: leaves body of mandible to emerge onto face, supply skin of lower lip, incisor plexus and labial peridontium of mandible incisors
2) _____: incisors and canines and 1st premolar
1) Mental Nerve
2) Incisive Nerve
The (surgical) removal of lower wisdom teeth (3rd molars) endangers what 2 nerves?
both the lingual and inferior alveolar nerves.
What’s a test of trigeminal (V) nerve function?
Test for altered sensation or a loss of taste (or a combination or progression of these symptoms)
mental nerve vs incisive nerve
The Inferior Alveolar Nerve (innervated by the trigenomal ganglia (V)) branches off into the MN and IN.
1) MN- leaves body of mandible to emerge onto face, supply skin of lower lip, incisor plexus and labial peridontium of mandible incisors
2) IN- incisors and canines and 1st premolar
The trigeminal ganglia (V) innervates thre Maxilla through the Superior Alveolar Nerve. 3 SA nerves are:
1) ______: doesn’t enter bone posterior molars
2) ______: roots of premolar
3) ______: intrabony; can’t be blocked w/ anesthesia
1) Gingival Branch
2) Dental Branch
3) Anterior Superior Alveolar Nerve
T/F: the Facial (VII) nerve innervates the muscles of mastication and the periodontal ligament.
False; the Trigenomal Nerve (V)
Gingival Branch vs Dental Branch vs Anterior Superior Alveolar Nerve
GB- doesn’t enter bone posterior molars
DB- roots of premolar
ASAN- intrabony; can’t be blocked w/ anesthesia
What 3 things does the facial (VII) nerve innervate?
- cutaneous innervation to the facial skin (controls facial expression)
- muscles of facial expression
- parts of the tongue
What 3 things does the glossopharyngeal (IX) nerve innervate?
- posterior soft palate
- uvula
- parts of the tongue
What 3 things does the vagus (X) nerve innervate?
- pharynx
- larynx
- esophagus
Generally, which of the cranial nerve do the following?- Also, which embryological pattern do these innervations mimic?
1) _____: involved with facial expression/ tongue
2) ______: innervate mouth nerves
3) ______: involved with the throat
4) ______: involved with mouth/ tongue
1) Facial Nerve (VII)- Arch 2
2) Trigenomal Nerve (V)- Arch 1
3) Vagus Nerve (X)- Arch 4-6
4) Glossopharyngeal Nerve (IX)- Arch 3
Nerve Innervation in the Parotid Gland- What’s the cranial nerve supply of the following:
1) paraympathetic
2) sympathetic
3) sensory
1) Glossopharyngeal Nerve (IX)
2) Superior Cervical Ganglion
3) Auriculotemporal Branch (V)
Stimulation of the Parotid Salivary Gland:
_______ stimulation produces a water rich, serous saliva. ________ stimulation leads to the production of a low volume, enzyme-rich saliva.
Parasympathetic stimulation; Sympathetic Stimulation
Parasympathetic vs Sympathetic Stimulation of the parotid salivary gland
Parasympathetic stimulation produces a water rich, serous saliva. Sympathetic stimulation leads to the production of a low volume, enzyme-rich saliva.
Multiple Nerves Innervate the Tongue:
1) _______: innervates 1st arch; anterior tongue
2) _______: innervates 2nd arch; gustatory innervation of anterior tongue
3) _______: innervates the 3rd arch; posterior tongue epithelium
4) _______: innerates 4th/ 6th arch; posterior tongue
1) Trigeminal Nerve (V)
2) Facial Nerve (VII)
3) Glossopharyngeal Nerve (IX)
4) Vagal Nerve (X)
What happens during week 3, week 4 and week 4-6 of the first trimester?
Week 3: Neurulation: formation of the brain and spinal cord from the ectoderm.
Week 4: Neural Crest Migration: from the neural tube into the face.
Week 4-6: Nerve innervation of the face: Cells from neural crest and placode form bases of peripheral nervous system.
