DH 306 Exam #1 Questions and Answers
1. How are the three periods of prenatal development categorized?: preimplan- tation period,
embryonic period, fetal period
2. What are the three embryonic cell layers?: ectoderm, mesoderm, endoderm
3. What tissues derive from the ectoderm?: epidermis, eyes, ears, nose, nervous system, neural
crest cells, mammary and cutaneous glands
4. What tissues derive from the mesoderm?: dermis, muscle, bone, lymphatics, blood cells and
bone marrow, cartilage, reproductive and excretory organs
5. What tissues derive from the endoderm?: respiratory and digestive system linings, liver, and
pancreatic cells
6. Where does the ectoderm sit after embryonic folding?: outside
7. Where does the endoderm sit after embryonic folding?: inside
8. Where does the mesoderm sit after embryonic folding?: middle
9. What is teratogen?: an agent or factor that causes malformation of an embryo.
10.What teratogen has an effect in congenital syphilis?: bacterial spirochete
11.What can syphilis lead to?: blindness, deafness, paralysis
12.What are some possible oral effects from syphilis?: Hutchinson's incisors and mulberry
molars
13.What teratogen has effect on tetracycline staining?: systematic antibiotic that binds
irreversibly to dentin
stains both sets of dentition
14.How many facial processes are there?: 5
15.What week does the face start to form?: 4
16.What week does the face reach complete formation?: 12
17.What is the origin of the stomodeum?: ectodermal depression enlarged by disintegration of
oropharyngeal membrane
18.What structures are associated with the stomodeum?: oral cavity proper
19.What is the origin of the mandibular arch?: fused mandibular processes and neural crest cells
(mandibular symphysis)
20.What branchial/pharyngeal arch is the mandible a part of?: first
21.What structures are associated with the mandibular processes?: lower lip, lower face, mandible
with associated tissues
22.What mandibular process is formed in part by neural crest cells?: mes- enchyme
23.What type of cartilage form's in each side of the mandibular arch?: Meckel's cartilage
24.What is the origin of the frontonasal process?: ectodermal tissue and neural crest cells
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, DH 306 Exam #1 Questions and Answers
25.What structures are associated with the frontonasal process?: forehead, bridge of nose,
primary palate, nasal septum, and all structures related to medial nasal processes
26.The frontonasal process forms:: nasal pits (olfactory pits)
27.The medial nasal processes fuse EXTERNALLY to form: middle portion of nose and middle
upper lip
28.The medial nasal processes fuse INTERNALLY to form: intermaxillary seg- ment
29.What do the lateral nasal processes give rise to?: ala
30.Fusion of the maxillary processes and the medial nasal processes form the: nares (nostrils)
31.What is the origin of the intermaxillary segment?: fused medial nasal processes
32.What structures are associated with the intermaxillary segment?: maxillary incisor region,
primary palate, nasal septum, and philtrum
33.What teeth are in the primary palate?: four maxillary incisors
34.What teeth are in the secondary palate?: canines and posterior teeth
35.How is the secondary palate formed?: formed by the fusion of 2 palatal shelves
36.The maxillary processes are formed by what?: mesenchyme provided by neural crest cells
37.The maxillary processes give rise to: the midface, upper lip sides, cheeks, secondary palate,
posterior part of maxilla, zygomatic bones, part of temporal bones
38.How is the upper lip formed?: formed from fusion of maxillary process and each medial
nasal process
39.What are the bilateral swellings that appear inferior to the stomodeum called?:
branchial/pharyngeal arches
40.How many branchial arches are there?: 6
41.What type of cartilage is in the first branchial arch?: Meckel's cartilage
42. What muscles of mastication are associated with the first branchial arch?-
: masseter, medial and lateral pterygoid, temporalis
43.What does the first branchial membrane become?: tympanic membrane (eardrum)
44.What does the first branchial groove become?: external auditory meatus (ear)
45.Are branchial grooves inside or outside?: outside
46.What nerve is associated with the first branchial arch?: cranial nerve V: trigeminal nerve
47.What is another name for the second branchial arch?: hyoid arch
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1. How are the three periods of prenatal development categorized?: preimplan- tation period,
embryonic period, fetal period
2. What are the three embryonic cell layers?: ectoderm, mesoderm, endoderm
3. What tissues derive from the ectoderm?: epidermis, eyes, ears, nose, nervous system, neural
crest cells, mammary and cutaneous glands
4. What tissues derive from the mesoderm?: dermis, muscle, bone, lymphatics, blood cells and
bone marrow, cartilage, reproductive and excretory organs
5. What tissues derive from the endoderm?: respiratory and digestive system linings, liver, and
pancreatic cells
6. Where does the ectoderm sit after embryonic folding?: outside
7. Where does the endoderm sit after embryonic folding?: inside
8. Where does the mesoderm sit after embryonic folding?: middle
9. What is teratogen?: an agent or factor that causes malformation of an embryo.
10.What teratogen has an effect in congenital syphilis?: bacterial spirochete
11.What can syphilis lead to?: blindness, deafness, paralysis
12.What are some possible oral effects from syphilis?: Hutchinson's incisors and mulberry
molars
13.What teratogen has effect on tetracycline staining?: systematic antibiotic that binds
irreversibly to dentin
stains both sets of dentition
14.How many facial processes are there?: 5
15.What week does the face start to form?: 4
16.What week does the face reach complete formation?: 12
17.What is the origin of the stomodeum?: ectodermal depression enlarged by disintegration of
oropharyngeal membrane
18.What structures are associated with the stomodeum?: oral cavity proper
19.What is the origin of the mandibular arch?: fused mandibular processes and neural crest cells
(mandibular symphysis)
20.What branchial/pharyngeal arch is the mandible a part of?: first
21.What structures are associated with the mandibular processes?: lower lip, lower face, mandible
with associated tissues
22.What mandibular process is formed in part by neural crest cells?: mes- enchyme
23.What type of cartilage form's in each side of the mandibular arch?: Meckel's cartilage
24.What is the origin of the frontonasal process?: ectodermal tissue and neural crest cells
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, DH 306 Exam #1 Questions and Answers
25.What structures are associated with the frontonasal process?: forehead, bridge of nose,
primary palate, nasal septum, and all structures related to medial nasal processes
26.The frontonasal process forms:: nasal pits (olfactory pits)
27.The medial nasal processes fuse EXTERNALLY to form: middle portion of nose and middle
upper lip
28.The medial nasal processes fuse INTERNALLY to form: intermaxillary seg- ment
29.What do the lateral nasal processes give rise to?: ala
30.Fusion of the maxillary processes and the medial nasal processes form the: nares (nostrils)
31.What is the origin of the intermaxillary segment?: fused medial nasal processes
32.What structures are associated with the intermaxillary segment?: maxillary incisor region,
primary palate, nasal septum, and philtrum
33.What teeth are in the primary palate?: four maxillary incisors
34.What teeth are in the secondary palate?: canines and posterior teeth
35.How is the secondary palate formed?: formed by the fusion of 2 palatal shelves
36.The maxillary processes are formed by what?: mesenchyme provided by neural crest cells
37.The maxillary processes give rise to: the midface, upper lip sides, cheeks, secondary palate,
posterior part of maxilla, zygomatic bones, part of temporal bones
38.How is the upper lip formed?: formed from fusion of maxillary process and each medial
nasal process
39.What are the bilateral swellings that appear inferior to the stomodeum called?:
branchial/pharyngeal arches
40.How many branchial arches are there?: 6
41.What type of cartilage is in the first branchial arch?: Meckel's cartilage
42. What muscles of mastication are associated with the first branchial arch?-
: masseter, medial and lateral pterygoid, temporalis
43.What does the first branchial membrane become?: tympanic membrane (eardrum)
44.What does the first branchial groove become?: external auditory meatus (ear)
45.Are branchial grooves inside or outside?: outside
46.What nerve is associated with the first branchial arch?: cranial nerve V: trigeminal nerve
47.What is another name for the second branchial arch?: hyoid arch
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