Exam III Review Flashcards
(190 cards)
1
Q
Weaver mutation
A
Specific behavioral defects related to abnormal function of the cerebellum; abnormally of the radial glial cells in cerebrum and consequent abnormal migration of the cells that normally form the granular layer of the cerebellar cortex.
2
Q
Reeler mutation
A
Abnormal behavior and absence of normal cortical layers
3
Q
What is the relation of reelin to reeler?
A
Reelin is defective in the reeler mutant; it is a stop signal for radial neuronal migration
4
Q
What are the major derivatives of the diencephalon?
A
Epi thalamus, thalamus, hypothalamus
5
Q
What are the 3 patterning centers in the forebrain and what signaling molecules do they use?
A
Rostral patterning center (FGF-8)
Dorsal patterning center (BMPs and Wnts)
Ventral patterning center (Shh)
6
Q
The topographical arrangement of the myelencephalon is almost identical to the spinal cord. What is the major topographical change?
A
Pronounced expansion of the roof plate to from the thin roof over the 4th ventricle
7
Q
Expression of which set of genes seems to be responsible for the differentiation of specific nuclei in the myelencephalon?
A
Hox genes
8
Q
What type of transformation do the nueral crest cells undergo when they break free from the neural tube?
A
Epithelial - mesenchymal transformation
9
Q
What factors are involved in the breaking free of neural crest to the neural tube?
A
Snail-1, snail-2 and Foxd3
10
Q
Neural crest cells form many components of the nervous system, but they do NOT form what?
A
Motor neurons
11
Q
Explain what happened in the following experiment: Transplant thoracic neural crest cells to the head region and vice versa
A
Neural crest cells from the trunk transplanted into head form most neural crest derivates, BUT cannot from cartilage or skeletal elements** even though this is normal for neural crest.
12
Q
Circumpharyngeal neural crest arise from where?
A
The area of somites 1-7
13
Q
What is the circumpharyngeal ridge?
A
And arc-shaped aggregation of cells passing behind the 6th pharyngeal arch which migrate ventrally and then cranially to provide a pathway for CN XII and related musculature
14
Q
Where do most neural crest cells from somites 1-3 pass ?
A
Into pharyngeal arches 4 and 6 or form cardiac crescent
15
Q
Neural crest cells from R4-7 make up what?
A
Make up the Vagal crest and form parasympathetic innervation for digestive tract
16
Q
Vagal neural crest arises from ?
A
Circumpharyngeal crest and exit from levels of somites 1-7
17
Q
Vagal neural crest cells are mostly associated with what?
A
Gut enteric system (parasympathetics)
18
Q
What factor maintains the competence of neural crest cells to differentiate into autonomic neurons?
A
Mash-1
19
Q
Waardenburg’s Syndrome - neurocristopathy of trunk and cranial NC
A
Caused by Pax3 mutations. Involves various combinations of pigmentation defects (commonly a white strip of hair), deafness, cleft palate, ocular hypertelorism. 1 type has hypoplasia of limb muscles.
20
Q
CHARGE - neurocristopathy of trunk and cranial NC
A
Colomba, heart disease, atresia of nasal choanae, retardation of development, genital hypoplasia in males and anomalies of the ear.
21
Q
DiGeorges’ syndrome - neurocristopathy of cranial NC
A
Associated w/ a deletion on chromosome 22; characterized by hypoplasia and reduced function of the thymus, thyroid, and parathyroid glands and cardiovascular defects, including persistent truncus arteriosis and abnormalities of the aortic arch
22
Q
Neurofibromas - neurocristopathy tumor and proliferation defect
A
Neurofibromas are peripheral nerve tumors. A disease associated w/ them is Neurofibromatosis aka Von Recklinghausens which is a common genetic disease manifested by multiple tumors of NC origin. Occasional gigantism of limb/digit and various other conditions
23
Q
The preplacodal region encircles what?
A
The cranial plate
24
Q
The preplacodal region is induced by what?
A
Cranial mesoderm (and neural tube); involves activation of FGF pathway and inhibition of Wnt and BMP
25
As BMP concentration progresses, what is the order of differentiation?
Placodes --> neural crest --> neural plate
26
Review major inductive events chart **
.
27
The optic stalk is a lateral evagination of the what?
Diencephalon - it enlarges distally to from the optic vesicle
28
The optic vesicle asymmetrically invaginates to from a cup-like structure with a groove along one side of it, what is the groove?
The choroid fissure - it is continuous w/ the groove in the optic stalk which is continuous with the posterior chamber of the eye
29
What artery uses the choroid fissure and optic stalk to pass into the posterior chamber of the eye?
Hyaloid artery
30
In mammals, absence of what gene results in early optic vesicle formation but then no more eye formation?
Pax6
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High concentrations what what inhibit the expression of Pax6?
Shh
32
Low concentrations of Shh in distal optic stalk has what effect?
Permits expression of Pax6 and development of optic vesicle which will lead to formation of the retina
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High concentrations of Shh in proximal optic stalk has what effect on eye formation?
Decreases expression of Pax6 and induces expression of Pax2
34
Function of Pax2
Will provide guidance of axons of ganglion cells from retina
35
Review Lens chart
.
36
What factor is necessary for corneal induction?
Pax6
37
In cornea formation, the underlying lens vesicle induces the overlying ectoderm to do what?
Transfrom from bilayered epithelium (simple cuboidal basal layer + flattened periderm) to transparent multi-layered cornea
38
What forms the retina?
The invaginated optic cup forms both the pigmented and the neural retina
39
Pigmented retina
Outer thin layer of the optic cup after invagination occurs - this is the only pigmented part of the body that doesn't need neural crest cells
40
What factors are necessary for the differentiation of the pigmented retina?
Otx2 stimulated by Shh
41
In the fixation of retinal polarity, what is fixed first?
The nasotemporal (anterior-posterior) axis
42
How is the nasotemporal axis established ?
By gradients composed of ephrins and receptors
43
What is fixed second in the fixation of retinal polarity?
The dorsoventral axis
44
The dorsoventral axis is established by what?
Antagonistic actions of Shh and BMP, along w/ ventropin, Tbx-5, Pax2, and Vax2.
45
Anopthalmos
Absence of an eye resulting from a mutation in RAX; very rare and can normally be attributed to lack of formation of the optics vesicle
46
Microphthalamos
Can range from an eyeball that is slightly smaller than normal to one that is almost vestigial; can be associated w/ a large # of genetic defects and various other causes including intrauterine infections. One of the most common components of rubella syndrome.
47
Colomba
Nonclosure of the choroid fissure of the iris during the 6th or 7th week results in its persistence
48
Rathke's pouch
Evagination from the roof of the stomodeal ectoderm
49
Rathke's pouch is the primordium for the ?
Anterior pituitary (adenohypophysis)
50
What cranial nerves arise from what arches?
Arch I: CN V - trigeminal
Arch II: CN VII - facial
Arch III: CN IX - Glossopharyngeal
Arch IV: CN X - vagus
51
Why does the first arch develop into jaws?
Because of the lack of Hox gene expression
52
What factor is necessary to keep arch 2 from differentiating into arch 1 and forming the jaws?
Hoxa-2
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The neural tube is the basic signaling center in craniofacial development. It's segmentation occurs as a result of what?
Hox gene expression - segmentation is carried over onto the neural crest cells giving rise to neural crest tissue
54
Pharyngeal arch derived musculature arises from?
Mesoderm from somitomeres
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Pharyngeal arch mesenchyme that doesn't consist of pharyngeal arch derived musculature is derived from?
Neural crest
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Except for _______________, mesodermal structures of the pharyngeal arches are derived from neural crest.
Pharyngeal muscles
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The Frontonasal ectodermal zone is induced by. ?
Shh from forebrain
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What is the Frontonasal ectodermal zone?
An ectodermal signal center involving the establishment of a dorsoventral gradient of FGF-8 (more dorsal) and Shh (more ventral)
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What factors are involved in the shaping of the tip of the snout?
Shh and FGF-8
60
What are the 3 facial primordia?
1. Frontonasal prominence - unpaired
2. Nasomedial processes
3. Nasolateral processes
61
What are the primordia for the jaws and from which arch do they arise?
Maxillary processes
Mandibular processes
Meckel's cartilage
Pharyngeal arch 1*
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Maxillary processes consist of ?
Neural crest derived from forebraine and midbrain
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Mandibular processes consists of ?
Neural crest derived from midbrain and hindbrain
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Meckel's cartilage
Slender, elongated cartilagenous rod that develops w/I the 1st arch. Derived from neural crest cells. The mandible forms around it.
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What type of bone is the mandible?
Membrane bone
66
What are the derivatives of Meckel's cartilage?
Articular and Quadrate bones
They're cartilagenous bone
67
TMJ
Synovial joint w/ an articular disk. Articular surfaces are the temporal bone and the mandibular condyle.
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Formation of the TMJ involved early expression of what?
Barx-1
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Fate of the articular and Quadrate bones
Quadrate: moves to middle ear and becomes incus
Articular: moves to middle ear and become malleus
70
Stapes is another middle ear bone that is derived from which arch?
Arch II
71
When does the palate form?
Between 6 and 10 weeks of development
72
What does the palate divide?
The common oronasal cavity into nasal and oral cavity - they remain connection together in the adult as the pharynx (Oro and naso)
73
What are the primordia for the palate?
Median palatine process (unpaired) and
| Lateral palatine process (paired)
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What forms the primary palate aka the premaxilla
Median palatine process
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What forms the secondary palate?
The lateral palatine process
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Dental lamina
C-shaped bands of oral ectoderm overlying neural crest mesenchyme
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Tooth bud
Epithelial downgrowth overlying neural crest mesenchyme and marking position of a single tooth
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Cap stage
Inverted cup-shaped layer of ectoderm (ameleoblast layer) capped by stellate reticulum and covering a mass of mesenchyme = dental papilla
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Bell stage
Cone-shaped primordium covered by stellate reticulum overlying the enamel organ
Enamel organ: ameloblasts make up outermost layer of the 2 layered covering
Dental papilla: odontoblasts form the outermost layer of the pulpy mass and lie under and adjacent to the ameloblasts (dentine)
80
What stage do the ameloblasts and odontoblasts come together for the first time?
Bell stage
81
Dental sac
A condensation of mesenchymal cells around the developing tooth which will form the cementum and periodontal ligament
82
What factor is necessary for tooth development to continue past the bud stage?
Pax-9
83
What factors creat non-tooth-forming spaces?
BMP-4 inhibits FGF-8 to do so
84
What establishes the cusps on tri/bi cuspid teeth?
Enamel knots
85
What does salivary gland development depend on?
Interaction b/w the epithelium and the underlying mesenchyme
86
Branching pattern of salivary glands depends heavily on what?
Shh
87
Describe the signaling in salivary gland development
Signaling between Shh and FGF occurs within the epithelium rather that between the epithelium and the mesenchyme as occurs in other types of glandular development
**entirely in epithelium**
88
Cleft lip
Lack of fusion of the maxillary and nasomedial processes. In the most complete form of the defect, the entire pre maxillary segment is separated from both maxillae, w/ resulting bilateral clefts that run through the lip and upper jaw b/w lateral incisors and canine teeth. Mechanism frequently underlying cleft lip is hypoplasia of the maxillary process that prevents contact b/w the maxillary and nasomedial processes from being established
89
Cleft palate
Results from incomplete/absent fusion of the palatal shelves. Usually multifactorial. Some chromosomal syndromes (trisomy 13) are characterized by increased incidence of clefts. other cases can be linked to the action of a chemical teratogen.
90
Holoprosencephaly
Includes a broad specutrm of defects, all based on defective formation of the forebrain (prosencephalon) and structures whose normal formation depends on influences from forebrain. Arises early in pregnancy and brain defects usually involve archencephalic structures (olfactory system). B/c of the influence of the brain on surrounding structures, esp cranial base, primary defects of forebraine often manifest externally as facial malformations, typically a reduction in tissue of the Frontonasal process. In extreme cases, it can take form of Cyclopia. Also reduction defects of the nose (proboscis). Root cause of holoprosencephaly occurs very early in embryonic development w/ disturbances in the ability of the prechordal palate and anterior ectoderm to secrete Shh
91
Dentinogenesis imperfecta
Teeth appear with blue-gray or Amber-brown and are opalescent. Can be nonsyndromic or associate w/ osteogenesis imperfecta
92
Amelogenesis imperfecta
Group of clinically and genetically heterogeneous disorders that affect the development of enamel and result in abnormalities of the amount, composition, and or structure of the enamel. Caused by mutations in a variety of genes important in enamel formation. Enamel may be hypoplasia, hypo mature or hypo calcified
93
What is the main organizer for pharyngeal arch development?
Foregut endoderm
94
The craniocaudal segmentation of the pharyngeal arches is determined by what?
Hox genes
95
Pharyngeal arches II and III require expression of what?
Hoxa-2 and Hoxa-3
96
Adult derivative of pharyngeal groove I
External auditory meatus
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Adult derivative of pharyngeal pouch I
Middle ear auditory tube
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Derivative of pharyngeal pouch II
Supratonsilar fossa
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Derivative of pharyngeal pouch III
Thymus, inferior parathyroid gland
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Derivative of pharyngeal pouch IV
Superior parathyroid gland, post-branchial body
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Arch I
Aka mandibular
Aortic arch: I - maxillary artery
N: V - trigeminal
Muscles: of mastication, tensor tympani, mylohyoid, tensor veli palatini, anterior belly digastric
Skeletal derivatives: malleus, incus, sphenomandibular ligament, Meckel's cartilage, tympanic ring
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Arch II
Aka hyoid
Aortic arch: II - hyoid and stapedial artery
N: VII - Facial
Muscles: of facial expression, stapedius, stylohyoid, posterior belly digastric
Skeletal derivatives: stapes, styloid process, lesser horn of hyoid, part of hyoid body
103
Arch III
Aortic arch: III - internal carotid
N: IX - Glossopharyngeal
Muscles: stylopharyngeus
Skeletal derivatives: greater horn of hyoid, part of hyoid body
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Arch IV
Aortic arch: IV - r. Subclavian and aorta
N: X - Vagus
Muscles: pharyngeal and laryngeal musculature
Skeletal derivatives: laryngeal cartilages
105
Describe the development of the 1st pharyngeal arch
NC derived from rhombomeres 1 and 2 and midbrain. Differentiation associated w/ Otx-2
106
What cartilage is found in the second pharyngeal arch ?
Reichert's -body and lesser horn of hyoid, stapes, and styloid process and ligament
107
The development of the second pharyngeal arch is influenced by ?
Hoxa2
108
The cervical sinus (temporary) is composed of what pharyngeal grooves?
2nd and 3rd
109
What is the relationship of the cervical sinus and the overlying enlargement of the second arch?
As development progresses, the posterior ectoderm of the second arch fuses w/ the ectoderm of a swelling (Cardiac swelling) just posterior to the 4th arch, thus causing the cervical sinus to disappear and the external contours of the neck to become smooth
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Where is the external auditory meatus derived from?
1st groove
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Derivatives of the first pouch?
Tympanic cavity of middle ear and auditory tube
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Derivative of second pouch
Fossa for palatine tonsils
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Derivative of third pouch
Inferior parathyroids and thymus
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The inferior parathyroid from the 3rd pouch respond to what?
High concentrations of Shh
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The thymus in the 3rd pouch responds to what?
High concentrations of BMP-4
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Derivatives of the 4th pouch
Superior parathyroids and postbranchial body
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What does the postbranchial body in the 4th pouch become?
Becomes incorporated into the thyroid as para follicular (C) cells with secrete calcitonin
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What does the thyroid gland begin as?
A node (anlage) of cells located on the ventral surface of the pharynx b/w the 1st and 2nd pairs of pharyngeal arches then grows down into underlying mesenchyme as thyroid Diverticulum
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The thyroid Diverticulum remains connected temporarily where and how?
To the floor of the pharynx via the throglossal duct
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What is the foramen cecum?
Opening of the thyroglossal duct persists as a small pit at the base of the tongue = foramen cecum
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Infundibular process
Ventral downgrowth from floor of Diencephalon that forms the neurohypophysis (posterior pituitary)
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Rathkes' pouch
Midline up growth from roof of stomodeum - forms a cup like extension distally that attaches to the infundibular process
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What does the inner layer of the cup of rathke's pouch adhere to and form?
Neurohypophysis and forms pars intermedia
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What does the outer layer of the cup of rathke's pouch do?
It is separated from pars intermedia by a narrow lumen called the residual lumen - will form the anterior pituitary (adenohypophysis)
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In all vertebrate embryos, the first kidneys to develop are what?
The pronephric kidneys
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Pronephric kidneys
Differentiate in humans from the anterior intermediate mesoderm at about 22 days gestation
127
Are the pronephric kidneys in mammals functional or non-functional ?
Non-functional - but required in order for the rest of the excretory system to develop
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What is the functional kidney in most embryos ?
Mesonephros
129
Describe the mesonephros in a salamander
The cranial part of the mesonephros does not function as a kidney in the adult. The functional caudal part is usually referred to as the opisthonephros (tail kidney)
130
Mesonephric tubules
Longer than pronephric tubules (solid cords) and are often sigmoid or convoluted in shape
131
Causally, each mesonephric duct forms an evagination called the ?
Ureteric bud or metanephric Diverticulum
132
Metanephric Diverticulum/ureteric bud
Pocket-like expansion grows into the surrounding mesenchyme of the mesonephric ridge during week 5 of gestation. It will give rise to the adult ureter, renal pelvis, and collecting tubules
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As the metanephric diverticula expand, they induce the surrounding mesenchyme to condense into the what?
Metanephrogenic blastemata / blastema
134
Metanephrogenic blastema form what?
Renal tubules of the adult kidney
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What is the effect of the metanephrogenic blastema on the ureteric diverticula?
The metanephrogenic blastemata have a reverse
inductive effect on the ureteric diverticula - Neither one can continue to develop in the absence
of the other. The metanephric tubules will not form in the
absence of the mesonephric duct.
136
Effect of europlakins
Make ureter epithelium impermeable to water
137
What factors repress GDNF in the anterior regions?
Slit-2 and robo-2
138
Potters sequence
Flattened nose, wide interpupillary space, receding chin, tapering fingers, low-set ears, hip dislocation, and pulmonary hypoplasia often resulting in respiratory failure and death. Classified as a set of malformations secondary to a primary disturbance in development (bilateral renal agenesis for example).
139
Horseshoe kidney
1 in 400. Kidneys are typically fused at their inferior poles. They cannon migrate out of the pelvic cavity b/c the inferior mes. Artery blocks them. Most cases are asymmtomatic but can obstruct ureters.
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Polycystic kidney disease
1 in 800. Manifested by the presence of 100s-1000s of cysts of different sizes w/I the parenchyma of the kidney.
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Extrophy of the bladder
Major defect in which the urinary bladder opens broadly onto the abdominal wall. Most commonly attributed to an insufficiency of mesodermal tissue of the ventral abdominal wall.
142
What are the first part of the reproductive system to develop?
Gonads - after the embryonic kidneys have been established
143
What is the "default" condition of the gonads when they are indifferentiated?
Female
144
What is the switch that determines whether the indifferent gonad will develop into an ovary or switch to testis?
SRY on the Y chromosome
145
What is within the medulla of the indifferent gonad?
Solid cords of cells called sex cords which have the potential to give rise to the seminiferous tubules containing Sertoli cells and interstitial cells in the event of a genetic male
146
What anastomoses with the sex cord in a genetic male?
Rete cords
147
In the genetic female, what is the outcome of the medulla of the gonads?
It regresses and the cortex forms the ovary
148
What separates the cortex from the medulla in the gonad?
The tunica albuginea - in adult gonad it will lie on the external suface of the testis but will be internalized in the ovary
149
The mesonephric tubules in the vicinity of the developing gonads will anastomose with what?
Rete cords
150
What is the fate of the rete cords in females?
Will later degenerate along with the rest of the medulla but some vestigial mesonephric tubules may be retained
151
In males, the mesonephric tubules will be retained as what?
Part of the closed duct system that converts sperm to the exterior = efferent ductules **
152
The external genitalia begin as what kind of structure?
Bipotential
153
What are three primordia that essentially give rise to the external genetalia in both sexes?
Genital tubercle - Genital folds - Genital swellings
154
Genital tubercle
Unpaired - will form either the glans penis or clitoris
155
Genital folds
More medial paired genital folds will fuse in the male to form the shaft of the penis but will remain infused in the female to form the labia minora
156
Genital swellings
Paired - most lateral of the primordia. They will fuse and form the scrotum in males or remain infused and form the labia majora in females
157
Primary heart field aka heart cresent forms what?
Left ventricle and the atria
158
What is phylogenetically the most primitive component of the mammalian heart?
The primary heart field aka heart cresent
159
Within the primary heart field, what are the most posterior cells exposed to and what does that cause?
Exposed to high gradient of RA and assume an atrial identity.
The more anterior cells are not exposed to RA and assume the default ventricular identity
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Anterior cells of the primary heart field that form the ventricles express what factor?
Hand-1 ** - it's absence results in defective left ventricle
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What does the secondary heart field form?
Right ventricle and proximal outflow tract
162
Where are cells from the secondary heart field derived from?
The pharyngeal mesoderm - can either for cardiac or skeletal muscle
163
Cells in the secondary heart field express what factor?
Hand-2
164
Proepicardium forms what?
The epicardium; the interstitial cells and vasculature smooth muscle; and gives rise to the coronary vasculature
165
When does the cardiac tube form?
Late in the 3rd week - called primary myocardium
166
The forming of the cardiac tube late in the 3rd week is guided by what factor?
Tbx-2
167
What is the cardiac tube composed of?
Mostly of cells from primary heart field but incorporates cells from the secondary heart field - it undergoes dextral looping which makes it the first asymmetrical embryonic structure to appear
168
What is the role of Hand-1 and Hand-2 in establishing asymmetry in the looping of the heart?
First, there is a shift in the expression of Hand-1 from both sides to the left side of the caudal heart tube. Hand-2 is expressed predominantly in the primordium of the right ventricle.
169
When atrial and ventricular bulges appear on the outer suface of the loop and at inflow end, what structure is formed?
Chamber myocardium
170
What guides the formation of the chamber myocardium?
Tbx-5
171
What are the results of cardiac looping?
S-shaped heart; original caudal inflow (atrium) is now dorsal to outflow part of the heart;
Outflow part of the heart = bulbous cordis**; leads to aortic sac and arch system; internal septum begins to divide ventricle; later an internal septum will divide atrium
172
What is the broader part of the bulbus cordis called?
Conus arteriosis
173
What is the narrow distal part of the bulbus cordis called?
Trunus arteriosis
174
When does partitioning of the single atrium into a left and right chamber being?
During the 5th week
175
Interatrial septum primum
Downward growth from cephalic wall of single atrium to endo cardinal cushion. Separates the atrium into left and right chambers
176
Interatrial septum secundum
Forms to the right of the septum primum and grows from dorsal to the ventral part of the atrium
177
Interatrial foramen primum
Space b/w the leading edge of the septum primum and the endo cardinal cushion. Right to left atrial shunt
178
Interatrial foramen secundum
Forms at the cephalic end of the septum primum through apoptosis. continues the right to left atrial shunt after the foramen primum closes w/ the funtion of the septum primum w/ the endocardial cushion
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Foramen ovale
Space formed w/i the septum secundum. Right to left atrial shunt.
180
What is the fate of the first and second pairs of aortic arches?
They form but later degenerate
181
What do the 3rd pair of aortic arches form ?
Internal carotids (along w/ the dorsal aortae cranial to 3rd arches)
182
External carotids are the cranial extensions of what?
The paired ventral aortae cranial to the third arches
183
The common carotids are derived from what?
Ventral aortae b/w the 3rd and 4th aortic arches
184
The right subclavian artery is formed by . . .
The right 4th aortic arch
185
The left 4th aortic arch forms the .. .
Aortic arch
186
The 5th pair of aortic arches . . .
Degenerate
187
The 6th pair of aortic arches become .. . .
Associated w/ the pulmonary system - dorsal portion becomes the ductules arteriosis shunt in the fetus and later the ligamentum arteriosus
188
** function of the ductus venosus
Permits oxygenated placental blood to bypass the capillary network of the liver
189
The left umbilical vein becomes the ?
***hepatic portal vein
190
The Right vitelline vein becomes the . . .
Right hepatic vein
