Exam 3- Neural and Neural Crest Development

Question 1

What happens week 3, week 4, and week 4-6 during the first trimester?

Answer 1

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.

Question 2

During week 3 of the first trimester, the nervous system forms from the _______ during gatrulation, which is divided into what 2 territories?

Answer 2

ectoderm

1) Neural Plate- compromises of columnar epithelium; becomes brain/ spinal cord
2) Lateral Ectoderm- cuboidal epithelium; becomes epidermis of skin

Question 3

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.

Answer 3

False; rostro-caudal axis

Question 4

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 ______.

Answer 4

neural folds; neural tube

neuropores

ectodermal epidermis

brain; spinal cord

Question 5

What are five steps of neurulation (formation of the neural tube)?

Answer 5

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

Question 6

What’s the difference between primary neurulation and secondary neurulation?

Answer 6

Primary neurulation involves formation of neural tubes

Secondary neurulation is formation of the neural tube at tail end

Question 7

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

Answer 7

tail bud; medullary cord; Medullary cord

Question 8

What’s the difference between the primary and secondary neurulation in terms of steps to get to a completed neural tube?

Answer 8

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

Question 9

Wnt, BMP, Shh, & FGF…. what are they responsible for?

Answer 9

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

Question 10

The internalized _______ expands and differentiates along its length to form discrete brain regions and the spinal cord

Answer 10

neural tube

Question 11

What brain regions does the neural tube expand/ differentiates into? (3)

Answer 11

forebrain, midbrain, and hindbrain

NOTE- also differentiates/ expands into spinal cord

Question 12

The neural tube expands and differentiates into the forebrain, hindbrain and midbrain. What are there components?

Answer 12

Forebrain: telecephelon + Diencephalon

Midbrain: mesencephalon

Hindbrain: metacephalon + myelencephalon

Question 13

What is spina bifida and anencephaly? How does it occur?

Answer 13

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

Question 14

What happens during week 4 of the first trimester?

Answer 14

neural crest migration: from the neural tube into the face

Question 15

What becomes the neural crest?

Answer 15

the ectoderm-neural tube border, that forms when the ectoderm closes over the neural tube as it forms

Question 16

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)

Answer 16

Wnt, FGF & BMP

Question 17

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.

Answer 17

tight junctions; polarized

Question 18

Hindbrain and caudal midbrain neural crest cells migrate into the ______, while and anterior midbrain and forebrain crest cells migrates to ______.

Answer 18

pharyngeal arches; forebrain regions

Question 19

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 _______.

Answer 19

rhombomeres; arch 1, arche 2, arch 3; HOX genes

Question 20

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.

Answer 20

pharyngeal arches; neural tube; mesenchyme

Question 21

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 ______.

Answer 21

gut tube; neural tube

Question 22

Holoprosencephalies-midline defects, Otocephalies, Retinoic acid Syndrome, DiGeorge Syndrome, Hemifacial Microsomia and Treacher Collins syndrome are all caused by what?

Answer 22

Abberant arch development/ neural crest defect

Question 23

Neural Crest Syndrom: Holoprosencephalies- what two things causes it

Answer 23

• midline defects caused by Shh, ethanol and excess vitamin A
• caused by defects in forebrain patterning, resulting in flat nose, hypotelorism and microcephaly

Question 24

Neural Crest Syndrom: Reinoic Acid Syndrom

Answer 24

• 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

Question 25

What happens during week 4-6 of the first trimester?

Answer 25

Nerve innervation of the face: Cells from neural crest and placode form bases of peripheral nervous system.

Question 26

What's difference between oligodendrocytes and Schwann Cell?

Answer 26

O- the insulation of the axons exclusively in the CNS (CONS) SC- insulation of axons in the PNS (pnS)

Question 27

_____ provide support and myelinate cells to increase conduction of signal.

Answer 27

Glia (i.e. Schwann Cells/ Oligodondrocytes)

Question 28

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

Answer 28

1) Sensory: single ganglia 2) Proximal (p) and distal (d) ganglia 3) parasympathetic 4) sympathetic

Question 29

Proximal sensory neurons arise from _____, and distal neurons arise from ______.

Answer 29

neural crest; placodes

Question 30

Proximal sensory neurons arise from neural crest, and distal neurons arise from placodes. What cranial nerves do they fuse into?

Answer 30

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.

Question 31

Which 4 cranial nerves allows for digastric jaw movement?

Answer 31

Trigeminal (V), Facial (VII), glossopharyngeal (IX) & Vagus (X)

Question 32

The Trigeminal Ganglia (V) innervate the _______ nerves in the maxilla and the ________ nerves in the mandible.

Answer 32

Superior Alveolar Nerves; Inferior Alveolar Nerves

Question 33

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

Answer 33

1) Mental Nerve | 2) Incisive Nerve

Question 34

The (surgical) removal of lower wisdom teeth (3rd molars) endangers what 2 nerves?

Answer 34

both the lingual and inferior alveolar nerves.

Question 35

What's a test of trigeminal (V) nerve function?

Answer 35

Test for altered sensation or a loss of taste (or a combination or progression of these symptoms)

Question 36

mental nerve vs incisive nerve

Answer 36

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

Question 37

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

Answer 37

1) Gingival Branch 2) Dental Branch 3) Anterior Superior Alveolar Nerve

Question 38

T/F: the Facial (VII) nerve innervates the muscles of mastication and the periodontal ligament.

Answer 38

False; the Trigenomal Nerve (V)

Question 39

Gingival Branch vs Dental Branch vs Anterior Superior Alveolar Nerve

Answer 39

GB- doesn't enter bone posterior molars DB- roots of premolar ASAN- intrabony; can't be blocked w/ anesthesia

Question 40

What 3 things does the facial (VII) nerve innervate?

Answer 40

- cutaneous innervation to the facial skin (controls facial expression) - muscles of facial expression - parts of the tongue

Question 41

What 3 things does the glossopharyngeal (IX) nerve innervate?

Answer 41

- posterior soft palate - uvula - parts of the tongue

Question 42

What 3 things does the vagus (X) nerve innervate?

Answer 42

- pharynx - larynx - esophagus

Question 43

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

Answer 43

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

Question 44

Nerve Innervation in the Parotid Gland- What's the cranial nerve supply of the following: 1) paraympathetic 2) sympathetic 3) sensory

Answer 44

1) Glossopharyngeal Nerve (IX) 2) Superior Cervical Ganglion 3) Auriculotemporal Branch (V)

Question 45

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.

Answer 45

Parasympathetic stimulation; Sympathetic Stimulation

Question 46

Parasympathetic vs Sympathetic Stimulation of the parotid salivary gland

Answer 46

Parasympathetic stimulation produces a water rich, serous saliva. Sympathetic stimulation leads to the production of a low volume, enzyme-rich saliva.

Question 47

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

Answer 47

1) Trigeminal Nerve (V) 2) Facial Nerve (VII) 3) Glossopharyngeal Nerve (IX) 4) Vagal Nerve (X)

Question 48

What happens during week 3, week 4 and week 4-6 of the first trimester?

Answer 48

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.