Final Exam 4 Flashcards
Which area derives from paraxial mesoderm (parachordal cartilages and occipital somites 1-4) and develops by endochondral ossification?
posterior chondrocranium
Expression of which gene characterizes the zone of polarizing activity (ZPA)
sonic hedgehog (Shh)
Limb muscles derive from which source?
paraxial (somatic) mesoderm
Limb somatic sensory neurons derive from which source?
neural crest cells
Expression of which gene is associated with initiation of limb growth?
FGF10
Limb bones and cartilages derive from which source?
lateral somatic mesoderm
Somatic motor neurons that regulate limb skeletal muscle derive from which source?
neural tube epithelium
What is the most sensitive period during development for limb malformations?
weeks 4-5
Maternal thalidomide ingestion early in the 4th week of pregnancy would most likely be associated with which limb anomaly?
amelia
The pharyngeal pouches derive from which source?
endoderm
The posterior one/third of the tongue principally derives from which structure?
posterior hypopharyngeal eminence
A cervical sinus fistula would most likely be associated with which structure?
tonsillar sinus
Taste sensation for the anterior two/thirds of the tongue is mediated by which cranial nerve?
CN VII
The intermaxillary segment that forms the primary palate derives from which structures?
medial nasal prominences
The line of fusion between the lateral nasal prominences and the maxillary prominences marks the formation of which adult structure?
lacrimal sac
Identify the structures or areas
primary palate
palatal shelves
Disruption of which structures would account for bilateral posterior cleft palate?
failed palatine shelf fushion
The auricle of the ear derives from the auricular hillocks located where?
1st and 2nd arches
Which layers contribute to the tympanic membrane (eardrum)?
ectoderm, mesoderm, and endoderm
The middle ear ossicles malleus and incus derive from which source?
1st arch
The semicircular canals derive from which structure?
utricular portion of otic vesicle
Most axons in the vestibulococlear nerve (CN VIII) represent which type of neuron?
bipolar neurons
Identify the germ layer of origin for the lung bud.
endoderm
Although the capability for actual gas exchange is limited, the stage of lung development marked by early alveolar development and initiation of surfactant production would be the?
terminal sac
What is the origin of the lung Type II cells?
endoderm
The pancreas develops from which embryonic layer?
endoderm
Which structure does not develop from the original hepatic diverticulum?
dorsal pancreas
Which structure derives from or in association with the dorsal mesogastrum?
greater omentum
Where does the spleen develop?
dorsal mesogastrum
Formation of the midgut primary intestinal loop depends on which major vitelline artery derivative?
superior mesenteric
Which adult organ derives from both the foregut and midgut?
duodenum
Which structure derives from the caudal limb of the primary intestal loop?
cecum and appendix
Failed retraction of the gut following physiological herniation results in?
omphalocele
Which characteristic do the lungs, pancreas, appendix and proximal rectum all share in common?
epithelium derives from endoderm
The definitive anal canal is composed of which tissues?
endoderm + ectoderm
A near-term infant had a light gray shiny mass protruding from the umbilicus. This mass appears to be covered by a thin transparent membrane. Closer inspection showed the mass to consist primarily of intestinal loops. What is the diagnosis?
omphalocele
Which structure develops from the ureteric bud?
collecting tubules
Which structure will connect directly to the urogenital sinus at some point during embryonic development?
all of the above
allantois, mesonephric duct & metanephric duct
What is the origin of the mesonephric ducts?
intermediate mesoderm
What is the origin of the metanephric blastemal?
intermediate mesoderm
Differentiation of the male gonads and ducts is dependent on a cascade of hormones and growth factors driven by the Y chromosome. Which sequence best describes this cascade in normal males?
TDF- Sertoli cells- MIS- paramesonephric tubule regression
What is the origin of the vas deferens?
mesonephric ducts
What is the origin of the prostrate gland?
urogenital sinus
What is the origin of the oviducts?
paramesonephric ducts
What is the origin of the distal vagina?
urogenital sinus
What is the origin of the body of the uterus?
paramesonephric ducts
Which structure represents the female counterpart of the male scrotum?
labia majora
What is the origin of the urogenital sinus?
endoderm
An early castrated male embryo supplemented with testosterone will have which duct arrangement?
mesonephric and paramesonephric ducts will be present
Bonus-
A child develops a large midline cyst just above the larynx. What is the likely origin of this cyst?
thyroglossal duct remnant
What are the basic roles of HOX genes, T-box genes and fibroblast growth factors (FGF) 10 and 8?
HOX - regulates body formation during development.
T-box - limb and heart development
FGF 10 - limb growth and wound healing
FGF 8 - forebrain
Explain why the AER (apical ectodermal ridge) is essential to limb development and, how the AER differs from the ZPA (zone of proliferating activity)
it forms ectodermal cells that act as major signaling centers to ensure proper development of a limb;
ZPA is essential for maintaining AER
What is embryonic limb rotation and why is it important?
it produces normal rotated limbs
What is the most sensitive period for limb malformations and why?
4-5 weeks because organogenesis occurs
What is thalidomide, what are its effects and when do they occur?
its a sedative, causes limb abnormality (amelia), happens in 4th week
What is a cervical sinus fistula and how does it develop?
deep depression on side of neck formed by 2nd-4th pharyngeal grooves merging
Outline the process of thyroid gland development and explain how you would distinguish between a cervical cyst and a thyroglossal cyst?
forms as proliferation of endodermal epithelial cells
- cervical cyst is in thyroid
- thyroglossal cyst is in midline mass
Describe the embryonic origins of the adult tongue and its cranial nerve innervation
occipital somites (hypoglossal XII), lateral tongue buds (trigeminal), copula (facial VII), anterior hypopharyngeal eminence (glossopharyngeal IX and vagus X)
What is the basis for salivary gland development?
on stomodeum ectoderm the parotid, on endoderm the submandibular and sublingual glands
Describe the process of nasal cavity formation.
oronasal breaks apart and causes opening of primitive choana which connects nasal and oral cavity
Which structures contribute to primary palate formation and what are their adult derivatives?
1st pharyngeal arch and frontonasal prominence-
nasal and oral cavity
Which structures contribute to secondary palate formation
anterior hard palate and posterior soft palate
Outline the embryonic origins and development of the external auditory canal and auricle of the ear
external auditory canal-1st groove
auricle of the ear-auricular hillocks
What are the embryonic origins of the tympanic membrane and middle ear cavity and ossicles?
tympanic membrane-1st membrane
middle ear cavity-1st pouch
ossicles-arch1: malleus and incus arch2: stapes
What kind of neurons make up most of the axons found in the vestibulocochlear nerve?
bipolar
Identify the germ layer of origin for the lung bud, visceral pleura, and parietal pleura
visceral pleura-splanchnic mesoderm
parietal pleura-somatic mesoderm
What is a tracheoesophageal fistula and why do they occur?
an abnormal connection between esophagus and trachea
List the three primary gut tube regions and outline the major arterial supply and venous drainage routes for each region
also adult derivatives
foregut -artery: celiac adult: pharynx, esophagus, liver, gallbladder midgut -artery: superior mesenteric adult: jejunum, ileum, cecum hindgut -artery: inferior mesenteric adult: transverse colon, descending colon, sigmoid colon, rectum Venous drainage: Portal venous system
Describe the location of the omental bursa, greater omentum, lesser omentum, epiploic foramen of Winslow and falciform ligament
falciform ligament-on liver
epiploic foramen of Winslow- above stomach below liver
lesser omentum-above stomach
greater omentum-hangs down from stomach
omental bursa-formed by lesser and greater omentum
Identify the germ layer origin for each of the following: seminal vesicles, prostate, bulbourethral glands, paramesonephric ducts, paraurethral glands, greater vestibular glands and vagina
seminal vesicles-mesoderm
prostate-endoderm
paramesonephric ducts-mesoderm
Outline the major derivatives of the genital tubercle and urethral and labioscrotal folds in males vs females
genital tubercle becomes penis or clitoris
urethral fold becomes labia majora
labioscrotal folds become scrotum
