test 2 head and neck

Question 1

Mesenchyme forming head and neck is derived from 3 major sources ___

Answer 1

neural crest
paraxial mesoderm
lateral plate mesoderm

Question 2

neural plate mesoderm gives rise to ___ of the head

Answer 2

Question 3

paraxial mesoderm gives rise to ___ of the head

Answer 3

Question 4

lateral plate mesoderm give rise to ___ of the head

Answer 4

Question 5

Patterning of the head and neck mesenchyme is closely coordinated with patterning of ___

Answer 5

neural epithelium

Question 6

•Vertebrate embryos pass through a ___ after organogenesis-recreating evolutionarily conserved structures that are highly resistant to evolutionary change

Answer 6

phylotypic stage

Question 7

___ segmentation is characteristic of the phylotypic stage

Answer 7

•Hindbrain

Question 8

Variation in vertebrate morphology arises after this conserved stage. What stage?

Answer 8

phylotypic stage

Question 9

___ segmentation is a conserved strategy used by

vertebrates for organizing the diverse craniofacial features

Answer 9

Hindbrain

Question 10

Rhombomeres: segments composed of ___ epithelial cells from Neurulation;

Answer 10

ECTODERMAL

Question 11

___ are precursors to hindbrain and peripheral neurons

Answer 11

rhombomeres

Question 12

rhombomeres not only produce neuronal tissue, they also coordinate ___ formation through interactions with mesodermal, ectodermal, and endodermal cells.

Answer 12

craniofacial

Question 13

rhombomeres directly contribute cells to ___ through the Epithelial to Mesenchymal Transition and migration of Neural Crest cells.

Answer 13

craniofacial bones and cartilages

Question 14

the neural tube closes and forms three major segments

Answer 14

forebrain (prosencephalon)

midbrain (medsencephalon)

hindbrain (rhombencephalon)

Question 15

rhombomeres are formed by segmentation of ___ and the neural crest undergoes ___ through EMT.

Answer 15

hind brain

delamitation

Question 16

Hox in mammals vs Hox in fly

Answer 16

control expression from cranial to caudal

mammals have duplication of Hox genes

4 orthologous sets of paralogs

Question 17

4 ___ sets of paralogs

Answer 17

orthologous

An orthologous gene is a gene in different species that evolved from a common ancestor by speciation.

Paralogs are homologous genes/proteins that are related or produced by duplication within a genome followed by subsequent divergence.

hox genes in mammals

Question 18

An ___ is a gene in different species that evolved from a common ancestor by speciation.

Answer 18

orthologous gene

Question 19

___ are homologous genes/proteins that are related or produced by duplication within a genome followed by subsequent divergence.

Answer 19

Paralogs

Question 20

The Hox code defines ___segmentation

Answer 20

rhombomere

Question 21

the 2nd rhombomere is controlled by ___

Answer 21

Hox A2

Question 22

pharyngeal arches are derived from ___

Answer 22

mesoderm and neural crest (ectoderm that went through EMT to become mesenchyme)

Question 23

pharyngeal cleft is derived form ___

Answer 23

ectoderm

Question 24

pharyngeal pouch is derived from

Answer 24

endoderm

Question 25

*The dramatic migration of neural crest cells from rhombomeres into mesoderm results in the formation of the \_\_\_*

Answer 25

*pharyngeal arches*

Question 26

\_\_\_ are exclusive derivatives of Pharyngeal arches that develop into gills of fish, and Pharyngeal arches are the proper ___ term.

Answer 26

*Branchial arches* mammalian

Question 27

Cells in the rhombomeres progressively lose the ability to respond to environmental signals. ie, *their epigenetic identity becomes progressively ___ over time*

Answer 27

*fixed*

Question 28

No evidence of pre-programming of fate- *there is ___ in the Hox code, but the ___ is lost with time.*

Answer 28

* plasticity* * plasticity*

Question 29

Cells transplanted from one rhombomere to another adopt new identities, unless they are transplanted in \_\_\_, where they maintain their original identity by ___ and \_\_\_

Answer 29

larger groups Cell-Cell communication, mutual reinforcement of identity.

Question 30

Note in the hindbrain, ___ is observed in single dispersed cells and ___ in cell groups or clusters.

Answer 30

plasticity autonomy

Question 31

*The ___ plays an important role in Hox code expression in neural crest cells of the rhombomeres*.

Answer 31

*mesoderm*

Question 32

•Rhombomere ablation does not affect patterning of the mesoderm (pharyngeal arch), endoderm (pharyngeal pouch) or outlying ectoderm (pharyngeal cleft)-initial patterning is *NOT DEPENDENT* on the \_\_\_

Answer 32

neural crest.

Question 33

mesodermal arch and endodermal pouch patterning evolved ___ rhombomere patterning

Answer 33

before

Question 34

The cranial mesoderm provides maintenance signals that ___ the program of Hox expression, but cannot ___ Hox gene expression in neural crest cells.

Answer 34

elaborate initiate mesoderm helps Hox but cannot make Hox

Question 35

*Hoxa2* expression is a critical determinant of ___ arch structures. It is ***necessary*** **and** ***sufficient*** for ___ arch identity

Answer 35

2^nd

Question 36

explain how Hox works basically

Answer 36

signaling molecules bind with transcription factors (Hox code) which trigger phenotypic gene down stream which specify cells identity

Question 37

\_\_\_ is the source of an inductive BMP signal to the neural crest.

Answer 37

•Pharyngeal endoderm

Question 38

\_\_\_ has also been shown to promote the formation of branchial arch components in amphibians by directing neural crest cells towards a chondrogenic fate.

Answer 38

pharyngeal endoderm

Question 39

Pharyngeal endoderm plays a major role in establishing and patterning the \_\_\_.

Answer 39

branchial arches

Question 40

•***Ectodermal clefts*** play an inductive role in ___ of the neural crest

Answer 40

odontogenesis (formation and eruption of teeth)

Question 41

odontogenesis

Answer 41

formation and eruption of teeth

Question 42

pharyngeal arch get most of their neural crest cells from which rhombomeres?

Answer 42

even number rhombomeres old number rhombomeres (migrate rostrally and caudally)

Question 43

what is the biggest pharyngeal arch and what supplies it

Answer 43

Nerve V, rhombomere 1,2,3

Question 44

pharyngeal arch 1 is formed by ___ and makes \_\_\_

Answer 44

NC cells from R1 and 2 (and a bit of 3) (the mandibular arch), forming jawbones, incus, malleus, as well as cranial nerves. Some of these cells also pulled by epidermis to form fronto-nasal process, making the forehead, mid-nose, and primary palate.

Question 45

There are six pairs of pharyngeal arches. In mammals, the ___ is a short-lived rudiment, so the pairs are numbered \_\_\_

Answer 45

fifth I, II, III, IV, VI. **There should be no V.**

Question 46

pharyngeal arch 2 is formed by ___ and makes \_\_

Answer 46

rhombomere 4 and some of 3 and 5 partial hyoid bone, stapes and facial nerve

Question 47

pharyngeal arch 3 and 4 is formed by ___ and makes \_\_

Answer 47

rhombomere 6-8 and some of 5 partial hyoid bone, thymus, parathyroid, thyroid, various cartilages and contribute to cardiac outflow tracts.

Question 48

pharyngeal pouches are __ derivatives and lead to \_\_

Answer 48

endodermal internal membranes:

Question 49

pharyngeal clefts are __ derivatives and lead to \_\_

Answer 49

ectodermal cervical sinus and external auditory meatus

Question 50

pharyngeal arch 1 forms which prominences?

Answer 50

dorsal maxillary ventral mandibular

Question 51

5 facial prominences (primordia)

Answer 51

**Frontonasal:** Forehead, bridge of nose **Medial nasal:** Philtrum of upper lip, crest/tip of nose **Lateral Nasal:** Ala of nose **Maxillary**: Upper lip **Mandibular:** Lower lip

Question 52

what is the area where the upper lip and nose fuse

Answer 52

philtrum

Question 53

Upper lip is formed by which prominences fusing

Answer 53

Maxillary prominences fuse with medial nasal prominences

Question 54

the lower lip and jaw are formed by what prominence fusing

Answer 54

mandibular prominences fuse at midline

Question 55

stomodeum

Answer 55

primitive mouth

Question 56

formation of the palate

Answer 56

first the medial nasal prominences will fuse to form the intermaxillary segment (primary palate) then the maxillary process will fuse to form the secondary palate

Question 57

\_\_\_ are extensions of Maxillary prominences

Answer 57

Palantine shelves

Question 58

when things go wrong with palatine shelf

Answer 58

cleft palate, tongue stuck to palate, palate stuck to mandible, **cyclopia and holoprosencephaly**

Question 59

cyclopia

Answer 59

caused by cyclopamine which inhibits Shh ## Footnote Cyclopamine is teratogenic by inhibiting sonic hedgehog signaling (Shh) via smoothened (*Smo*) inhibition exposure to this toxin during different days of gestation can lead to minor to severe issues, **day 22-30= cleft palate**

Question 60

nested expression of ___ genes-- specifies upper and lower jaw identity in ___ and teleosts--is a primitive feature of the mandibular, hyoid and gill arches of \_\_\_.

Answer 60

Dlx mammals jawed vertebrates (sharks)