Exam 1 Flashcards
(138 cards)
1
Q
What two periods make up the first trimester?
A
Preimplantation period and embryonic period
2
Q
____ and _____ molecules act through signaling complexes which activates _____ factors, affecting ____ changes
A
Growth factors
Cell adhesion
Transcription
Cellular
3
Q
The cellular changes induced by growth factors and cell adhesion molecules can cause what kinds of cellular changes?
A
Proliferation
Differentiation
Apoptosis
4
Q
Name some things that the growth factor BMP is responsible for
A
Craniofacial development
At gastrulation, it switches between epidermal vs. neural fate
Patterning and formation of facial primordia
Control of neural crest cells**
Regulator of early tooth morphogenesis and differentiation
5
Q
What types of genes code for transcription factors that make cells pattern into one tissue/organ type or another? These genes are also involved in bodily segmentation during embryonic development.
A
Homeobox genes
6
Q
True or false… cell adhesion molecules are responsible for specific cell aggregation and sorting and involves cell-cell contact.
A
True
7
Q
in regards to cell adhesion molecules… Cadherins are calcium ____ whereas CAMs are calcium _____
A
Dependent
Independent
8
Q
Neuroectoderm progenitors express ____ while skin ectoderm progenitors express ____
A
N CAM
L CAM
9
Q
What period takes place during the first week after conception? Describe what occurs in this period.
A
Preimplantation period
An oocyte (arrested in metaphase 2) is penetrated by sperm to form a diploid zygote. The zygote undergoes cleavage to form a solid morula (day4), then a vesicle called a blastocyst.
10
Q
True or false… if nondisjunction occurs in meiosis 1, it is possible to produce normal haploid gametes.
A
False. None of the gametes will be normal as half will be N + 1 while the other half will be N - 1.
If, however, nondisjunction occurs in meiosis 2, you will get half normal gametes, one N + 1, and one N - 1.
11
Q
Describe the difference between the trophoblast and embryblast.
A
In a blastocyst, the outer portion of cells are called the trophoblast. The internal fluid pushes the inner cell mass to one side, this is called the embryoblast.
12
Q
True or false… no differentiation occurs during cleavage
A
True
13
Q
True or false… the morula is what implants into the endometrium
A
False.. it is the blastocyst that implants into the endometrium
14
Q
The trophoblast will give rise to the ___
A
Placenta
15
Q
Describe where you would find the primary yolk sac in a blastocyst
A
It is the ‘internal fluid’ of the blastocyst. It is between the embryoblast and the trophoblast
16
Q
Which is important for implantation, the trophoblast or the embryoblast?
A
The trophoblast. This is what invades the endometrium
17
Q
Name some basic patterning events that occur during the embryonic phase?
A
Axial specification (which end is up)
Segmentation
Tissue and organ specialization and formation
18
Q
Define induction
A
When one group of cells tells another group of cells, which are said to be competent, to do something
19
Q
Define proliferation
A
Cell division. Increase in number and accumulation
20
Q
Define differentiation
A
Development of specific structures and or functions by individual cells or groups of cells
21
Q
Define morphogenesis
A
Cell migration, interactions and proliferations, causing the development of groups of cells
22
Q
Define maturation
A
Attainment of adult size and function from proliferation, differentiation, and morphogenesis
23
Q
After the blastocyst implants, the embryoblast differentiates into what two layers? What will these layers give rise to? What types of cells make up each of these layers?
A
Epiblast (dorsal cells), (high columnar): these will give rise to amniotic cavity and the three germ layers
Hypoblast (ventral cells), (small cuboidal): form the roof of the secondary yolk sac and some of the endoderm
24
Q
True or false… the openings (mouth and anus) have direct contact between ectoderm and endoderm
A
True
25
After formation of the bilaminar disk, a structure called the ____ is formed which defines the future bilateral symmetry along the rostral-caudal axis.
Primitive streak
26
The ____ forms at the rostral end where the ectoderm curve around to integrate with the endoderm. This will give rise to the mouth
Prochordal plate
27
Describe how mesoderm is formed
Induced epiblast cells will essentially fall into the primitive streak and migrate outwards in between the epiblast and hypoblast layers
28
During gastrulation, ectodermal cells invaginate at the ___, forming the ____
Primitive node
Primitive pit
29
Other than the formation of the three germ layers, what other important structure is formed during gastrulation?
The notochord
30
True or false... the induced epiblast cells that fall into the primitive pit are called mesoblast cells. These cells will give rise to both mesoderm and endoderm
True
31
The cecal plate will give rise to the ____
Anus
32
The stomodeum (also known as the ____), is covered with the ______
Primitive mouth
Oropharyngeal membrane
33
True or false... the epithelium lining the oral cavity is derived from endodermal cells
False... it is derived from ectodermal cells
34
True or false... both enamel and dentin are derived from ectodermal cells
False... the enamel is derived from ectodermal cells whereas the dentin is derived from neural crest cells
35
In the oral cavity, the neural crest cells will give rise to the ___, ___, ____, and ____
Dentin
Pulp
Cementum
PDL
36
After week three (post gastrulation), what three key events take place?
Differentiation of the nervous system
Formation/migration of the neural crest
Embryo folding
37
What are the three main folds in embryo folding?
Lateral folds, head fold, tail fold
38
The onset of folding occurs at day ___
24
39
The neuroectoderm, a specialized group of cells that differentiates from the regular ectoderm, extends from the cephalic end to caudal end. The plate undergoes further growth and thickening which causes it to deepen and invaginate inward to form the ____. When this invagination closes in on itself, it is called the ____
Neural groove
Neural tube
40
If you replace BMP and Wnt with FGF. ____ will be induced to become ____
Ectoderm
Neuroectoderm
41
Describe neural tube closure
The neural fold fusion begins at upper cervical levels, then closes in both directions rostrally and causally
42
A defect in the neural tube closure can result in ____
Spina bifida
43
The differentiated ____ gives rise to somites on either sides of the developing nervous system. The somites are further differentiated into three sections. Name these sections and what each one gives rise to
Mesoderm
Paraxial - cartilage, segmented muscle
Intermediate - kidneys, gonads
Lateral plate - heart, gut
44
The neural tube expands to form the forebrain, midbrain, and hindbrain. The hindbrain segments into ____ which express ___ genes
Rhombomeres
Hox
The branchial arches develop in the head region too
45
The neural ectoderm develops from the ___ during the ___ week
Neuroectoderm
Third
46
True or false... the head fold is critical to the formation of the oral cavity
True
47
Bone is _____ formed on a ____ matrix with various _____ proteins
Hydroxyapatite
Collagenous
Non-collagenous
48
Describe the difference between endochondral and intramembranous ossification. What kind of bones do each process form?
Endochondral - bone that is formed on a cartilage template (long bones).
Intramembranous - bone that is formed from condensation of mesenchyme (most of the mandible, skull plates)
49
What is mesenchyme?
Cells floating around in ECM that can form CT
50
True or false... other than serving as a template for endochondral ossification, cartilage can also drive the formation of bone by intramembranous ossification through signaling
True
51
Define initiation
Start of ossification, whether conversion of cartilage to bone or condensation of mesenchyme/neural crest to bone
52
Define growth in regards to bone
Addition of more bony matrix to a pre-existing bone; thickening/elongation.
Depends on the rate of resorption and bone deposition
53
Describe the difference between primary displacement and secondary displacement
Primary - movement of a bone due to its own growth (finger goes further out because of lengthening of finger bone)
Secondary - movement of a bone due to the growth of surrounding bones (finger goes further out because of growth of arm)
54
Define remodeling in regards to bone
Growth involving simultaneous deposition and resorption on all peri-endosteal surfaces; changes size, shape, proportion, relationship with adjacent structures
Involved in healing. For example, when you fracture a bone, it is immediately filled with weak collagen 3. Then it is displaced by collagen 1 by the action of osteoblasts and osteoclasts
55
Define drift in regards to bone
Remodeling that results in movement of a bone towards the deposition surface
56
Define functional matrix in regards to bone
A tissue that guides a bone's growth by exerting a force upon the bone
57
Describe how bones grow 'wider'
Removal from the endosteal surface while depositing on the periosteal surface
58
True or false.. bone only grow in the direction in which they are depositing
False. It depends on the rate of resorption and deposition. It is possible for growth to occur the opposite direction in which bone is depositing
59
True or false... on a single bone, all of the surfaces have the same rate of resorption/deposition
False. Some surfaces grow more than others, which is what give bones their shape as opposed to "horrific spheres"
60
Describe the difference between growth fields, sites, and centers
Growth fields - where matrix can be laid down or resorted
Growth sites - fields of significance to growth of a bone (maxillary tuberosity)
Growth centers - special growth sites, control overall growth of bone (epiphysial growth plates or long bones)
61
What is the calvaria? What about cranial base?
Calvaria - The 'skull cap'. Comprised of frontal, parietal, occipital, temporal, and sphenoid bones.
Cranial base - base of the skull
Both are part of the neurocranium
62
The calvaria (also known as the desmocranium) ossifies by ____ and is derived from ____ and _____
Intramembranous ossification
Paraxial mesoderm and neural crest cells
63
The cranial base, also called the chondrocranium, ossifies by _____, and derived from ____
Endochondral ossification
Neural crest cells
(Derived from special sense organ capsular tissues)
64
The ____ grows much more postnatally than the _____
Viscerocranium (face bones)
Desmocranium (brain bones)
65
In the calvaria, the condensed mesenchyme forms a bilayer membrane that encapsulates the developing brain. Name both of these layers and what they are.
Endomeninx (inner layer) - neural crest, gives rise to pia mater and arachnoid mater
Ectomeninx (outer layer) - neural crest and paraxial mesoderm, gives rise to the dura mater and the calvaria bone
66
What is anencephaly?
Failure of rostral neural tube to close (~week 4). Results in loss of the telencephalon
The calvaria does not form because the brain is required for calvaria ossification
67
What is craniosynostosis?
Premature fusion of the cranial vault sutures
Variable defects including deformities of calvaria and neurological defects
68
Explain how the cranial base (chondrocranium) forms.
Ectomeninx in floor of brain forms cartilage in response to notocord and other epithelial signals. This becomes the chondrocrainum. This will later undergo ENDOCHONDRAL ossification
69
Growth of the_____ and _______ plays a role in downward/forward growth of the midface (maxilla).
Nasal septal cartilage
Chondrocranium
70
Describe the difference between the maxilla proper and the premaxilla?
Maxilla proper - intramembranous ossification of mesenchyme, forms from maxillary prominence/process (bulk of the maxilla)
Premaxilla - intramembranous ossification of mesenchyme, forms from frontonasal processes and primary palate. Fuses early with maxilla proper. This is the portion of the maxilla the holds the anterior incisors
71
Describe secondary cartilages in the maxilla
Zygomatic process, alveolar plate, hard palate between palatine processes, mostly fetal growth roles
A lot of these will breakdown during development
72
Secondary displacement at sutures pushes the maxilla ___, ____, and ____
Down
Forward
Out
73
True or false... Mekel's (located in the mandilbe) cartilage is part of endochondral ossification as it serves as a template for bone formation
False. Mekel's cartilage simply drives the surrounding tissues to form bone, it does not participate in endochondral ossification.
74
What type of cartilage is meckel's cartilage?
Hyaline. (Bone forms lateral to Meckel's cartilage)
75
Meckel's cartilage largely disappears ____ and does not actually become the mandible proper. Its secondary cartilage, however, make up the ___, ____, and ____ cartilages at 10-14 weeks of development
Anteriorly
Condylar
Coronoid
Symphyseal
76
The only bit of the mandible that undergoes endochondral ossification is the ____
Condyle. However, condylar cartilage remains at the articular ends on the head.
77
True or false... the cartilage found on the articular end of the head of the condyle is considered secondary cartilage
True
78
The ____ cartilage disappears before birth, and the ____ cartilages (2) disappear in the first year of birth. They contribute transiently to the growth and development of the surrounding tissues
Coronoid
Symphyseal
79
Condyle cartilage is an important growth center for the ____, driving ___ ossification, and then ossifies itself through ___ ossification
Ramus
Intramembranous
Endochondral
80
What are the two general phases of pharyngeal arch development?
Formation of pharyngeal system
Development of pharyngeal derivatives
81
Neural crest migration and invasion of the pharyngeal system occurs during what week?
~4-6
82
Define the following... cysts, sinus, fistula
Cysts - sealed cavity filled with air, pus fluid
Sinus - cavity within a tissue, can open externally
Fistula - abnormal connection between two structures
83
How many pharyngeal arches do we have? Why is the 5th, missing?
How many pharyngeal grooves? Pouches? What are pharyngeal membranes?
Arches 1-6. 5 is missing due to evolutionary history
Pharyngeal grooves - 4 pairs
Pharyngeal pouches - 4 or 5 pairs
Pharyngeal membranes - between the arches
84
At which stage in development do the pharyngeal arches emerge? What week is this?
At neural tube closure
~4th week
85
The first pharyngeal is kind of split into two segments, the ____ and the ____
Mandibular prominence (larger, more caudal)
Maxillary prominence
86
True or false, the pharyngeal arches contain all 3 (and neural crest) layers.
True
87
The endoderm in between each arch is called a ____ while the ectoderm in between each arch is called a ____
Pouch
Cleft/groove
88
Early arches are ____ and ____
Continuous
Iterative
89
The oropharyngeal/buccopharyngeal membrane separates the ___ from the ___ . This structure breaks down at week ___
Stomodeum
Gut
4
90
What are the 5 components of pharyngeal arches?
An aortic arch. An artery that arises from the truncus arteriosus of the primordial heart.
A cartilaginous rod that forms the skeleton of the arch
A muscular component that differentiates into muscles of the head and neck
A nerve that supplies the mucosa and muscles from the arch
Neural crest
91
Aortic arches arise from ____ of the pharyngeal arches. They bridge between the ___ and the ___
Mesoderm
Truncus arteriosus (common arterial trunk of developing heart)
Dorsal aorta
92
Aortic arches 1 and 2 largely disappear. Some remain and form the ____, ___, and ___.
Maxillary artery (1)
External carotid artery (1)
Stapedial (2)
93
Aortic arches 3, 4, and 6 remodel to form portions of ____, ____, and ____
Common and internal carotid (3)
Aorta, subclavian (4)
Pulmonary (6)
94
Name some definite structures formed by the cartilaginous component of each arch
Arch 1: meckel's cartilage(in mandible), malleus, incus, maxilla, temporal bone, mandilbe, zygomatic bone
Arch 2: body of hyoid, stylohyoid ligament, styloid process, stapes
Arch 3: greater and lesser horn of hyoid bone.
Arch 4: thyroid cartilage
Arch 6: cricoid cartilage
95
Name some muscles that each arch will form.
```
Arch 1: muscles of mastication
Arch 2: muscles of facial expression
Arch 3: stylopharyngeus
Arch 4: pharyngeal constrictors
Arch 6: laryngeal muscles
```
96
Sensory cranial nerves are ___ derived whereas motor cranial nerves are ___ derived
Neural crest and ectodermal placode derived
CNS derived
97
Pharyngeal arch 1.
Nerves
Muscles
Skeleton
Composed of the mandibular prominence and the maxillary prominence
Nerves: Trigeminal V2 and V3
Muscles: muscles of mastication (temporalis, masseter, medial and lateral pterygoids)
Skeleton: Meckel's cartilage, maxilla, mandible, malleus, incus, zygomatic bone, part of temporal bone
98
Pharyngeal arch 2.
Nerves
Muscles
Skeleton
"Hyoid arch"
Nerve: facial nerve (VII)
Muscles: all muscles of facial expression
Skeleton: stapes, styloid process, stylohyoid ligament, body of hyoid and lesser horn
99
Pharyngeal arch 3
Nerve
Muscles
Skeleton
Nerve: glossopharyngeal
Muscles: stylopharyngeus
Skeleton: greater horns of hyoid
100
Pharyngeal arch 4
Nerves
Muscles
Skeleton
Nerves: vagus (superior laryngeal)
Muscles: pharyngeal constrictors
Skeleton: thyroid cartilage
101
Pharyngeal arch 6
Nerve
Muscle
Skeleton
Nerve: vagus (recurrent laryngeal)
Muscles: laryngeal muscles
Skeleton: cricoid cartilage
102
Which prominence is split in two?
Maxillary prominence. They must fuse together in development
103
In regards to the first pharyngeal arch, describe the differences between the mandibular and maxillary processes.
Mandibular process forms: lower lip, lower face, chin, lower cheek region, mandible, body of the tongue
Maxillary process forms: midface, upper cheek region, upper lip sides, secondary palate, maxilla, zygomatic bone
104
What is treacher collins syndrome?
A mutation in the treacle gene results in failure of the neural crest cells to properly migrate into the 1st arch. Causes hypoplasia of catch derived facial bones such as mandible, and zygomatic bones. These patients frequently have cleft palate and tooth defects
105
What is pierre robin sequence?
Cause is unknown.
Hypoplasia of the mandible, misplaced tongue.
106
Pharyngeal clefts are lined with ___. Cleft ___ is the only cleft normally NOT obliterated in development. The rest can persist in abnormal situations
Ectoderm
1
107
Pharyngeal cleft 1 gives rise to the ___. If the others fail to obliterate, they can result in ___
External auditory meatus.
Preauricular sinuses
108
What are congenital auricular sinuses and cysts?
Small sinuses and casts commonly found in the skin anterior to the ear.
Remnant of pharyngeal groove
Usuallly pretty irrelevant, unless it gets infected, or if it is a fistula going into the auditory canal.
109
Describe lateral cervical sinuses/cysts/fistulas and internal branchial sinuses cysts/fistulas.
Lateral cervical: uncommon, open externally, failure of second groove or cervical sinus to obliterate
Internal branchial: rare, persistent second pouch, open into tonsillar cleft (into pharynx) ... (note that it is also possible to have external branchial fistula)
110
The pharyngeal pouches form as pits internally in the pharynx, between the arches. The pouch linings are ____ in origin.
Endodermal
111
The first pharyngeal pouch forms the ___ and meets with the ___ to form the ____
Auditory tube
First pharyngeal groove
Tympanic membrane and middle ear
112
The ossicles are formed by which arches?
| The tympanic membrane is formed by...?
First and second arch. (Derived from neural crest)
First cleft and pouch membranes meeting together (later neural crest)
Note that the proximal auditory tube is narrow while the middle ear widens
113
The second pharyngeal pouch forms the ____
Lining (epithelium) of the crypts in the palatine tonsils.
The tonsils themselves are composed mostly of mesoderm
114
What does the third pharyngeal pouch form?
Gives rise to the inferior parathyroid glands (dorsal wing) and the thymus (ventral wing)
Note that the inferior parathyroid gland ends up inferior to the superior parathyroid glands because the inferiors travels with they thymus before moving over to the thyroid
115
What does the fourth pharyngeal pouch form?
Gives rise to the superior parathyroid glands (dorsal wing) and the ultimobranchial body (ventral wing) (this is an embryonic structure in which parafolliclar cells (C Cells) are derived, which produce calcitonin in the thyroid)
116
True or false... the thymus, since it develops from pouches (which are bilateral) it must migrate downwards and towards the midline to meet up with its counterpart
True
117
What are some abnormalities resulting from defects in migration of the thymus?
Cervical thymus - cord of thymus persists in the neck on its path of descent
Accessory thymus - piece of thymus remains in the path of descent
Note that this is usually unilateral
Note that these abnormalities can also occur with the parathyroid gland and thyroid gland
118
What is Digeorge syndrome?
CATCH 22
Chromosome 22 is missing. Failure of 3rd and 4th pouches to differentiate into thymus and parathyroid due to neural crest defects. Symptoms are...
Cardiac abnormality (tetralogy of fallot)
Abnormal facies
Thymic aplasia (immunocompromised)
Cleft palate
Hypocalcemia/hypoparathyroidism
119
What is tetralogy of fallot?
Defect in the heart. It consists of...
Ventricular septal defect
Pulmonic stenosis
Right ventricular hypertrophy
Overriding aorta
120
What are pharyngeal membranes?
Form where the epithelia of the grooves and pouches approach each other. Tympanic membrane!
Remaining regions between arches do not remain as membranes, they are obliterated during development
The oropharyngeal membrane is not a pharyngeal membrane!
121
Hox genes are involved in body ____. They typically involve switching on cascades of other genes
Segmentation
122
Neural crest cells with different ___ identities as determined by ____ expression, migrate from the ___ into the ____
A-P
Hox
Rhombomeres
Pharyngeal arches
123
Loss of ___ expression causes arch 2 to lose its ___ identity. Arch 2 will then give rise to ______ structures
Hox
A-P
Duplicate arch 1
124
Describe how neural crest is patterned in both the A-P (anterior posterior) orientation and proximal-distal
Neural crest is organized A-P by Hox genes (inter-arch). Neural crest is organized proximal-distal by DLx genes (intra-arch). The combination of these genes will determine what structure should be formed by the neural crest cells
125
At what week does the tongue begin to develop?
Week 4
126
In which arch is the median tongue bud located?
Arch 1 (week 4). This will later split into the distal tongue buds (week 5)
127
Describe each arch's contribution to the development of the tongue
Arch 1: forms anterior 2/3 of the tongue epithelium.
Arch 2: it is covered up as arch3 portion grows
Arch 3: forms most of the remaining 1/3 of the tongue.
Arch 4: forms just a bit of the tongue at the very back of the throat
128
At week 4, arch 2 forms a midline swelling called the ____. During weeks 5-6, this is overgrown by the _____ of arch 3. The ____ arises posterior to this structure.
Copula
Hypopharyngeal eminence
Epiglottis
129
The tongue muscles (besides palatoglossus) are not pharyngeal in origin. Rather, they come from ____
Occipital somites.
130
A review of tongue innervation. Describe each nerve's role in the tongue. 5,7,9,10,12
```
5 - sensory, anterior 2/3
7 - taste, anterior 2/3
9 - sensory/taste, posterior 1/3
10 - sensory, in pharynx
12 - tongue muscles (besides palatoglossus)
```
131
The terminal sulcus in the tongue divides the ___ and the _____.
Oral tongue (anterior 2/3, coming from arch 1, CN 5 innervation)
Pharyngeal tongue (posterior 1/3, coming from arch 3 mostly, CN IX innervation)
132
What is the foramen cecum?
Structure in the midline of the tongue that is the site of thyroid primordium
133
The thyroid forms from an _____ just posterior to the floor of the ___ arch (note that this is not a pharyngeal pouch). The thyroid does not form bilateral like the thymus, it originates on the ____. As the thyroid descends/elongates, it forms the ____, which connects to the tongue at the _____.This will allow the gland to remain in contract with the tongue early, but the ____ is obliterated later in development.
```
Endodermal diverticulum
1st
Midline
Thyroglossal duct
Foramen cecum
Thyroglossal duct
```
134
Thyroglossal duct cysts/sinuses may form due to...
Failure of the thyroglossal duct to completly pinch off and degenerate. The cysts/sinuses may form anywhere along the course followed by the thyroglossal duct.
These anomalies a typically asymptomatic and painless unless infected. Note that these will always form at the MIDLINE
135
How can you tell the difference between a cervical cyst/sinus and a thyroglossal cyst/sinus?
Thyroglossal cyst/sinuses will always form at the midline.
136
How can you diagnose a patient with ectopic thyroid?
Giving the patient radioactive iodine, taking a radiograph, and located where the iodine went.
Ectopic thyroids are less functional than normal thyroids
137
The pituitary gland forms from the ____ invagination of the _____ of the ___ (____ (This is NOT a pharyngeal pouch)) into contact with the ____.
Upward
Oral ectoderm
Stomodeum
Rathke's pouch
Diencephalon
138
Define neurophyophysis and adenohypophysis
Neurohypophysis - develops from the developing brain (neural ectoderm). (Only ADH and oxytocin are formed here)
Adenohypophysis - develops from the stomodeum roof (oral ectoderm)
