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First Aid Embryology
5.28
165
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05/28/2012

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Term
What is sonic hedgehog gene responsible for?
Definition
patterning along the anterior posterior axis
Term
Where is Wnt-7 gene product produced?
Definition
apical ectodermal ridge (thickened ectoderm at distal end of each limb)
Term
Where is sonic hedgehog gene product produced?
Definition
base of limbs in zone of polarizing activity
Term
What is the Wnt-7 gene responsible for?
Definition
proper organization along the dorsoventral axis
Term
Where is the FGF gene produced produced?
Definition
apical ectodermal ridge
Term
What is the function of the FGF gene?
Definition
stimulates mitosis of underlying mesoderm, providing for lengthening of limbs
Term
What is the funciton of the homeobox genes?
Definition
involved in segmental organization of embryo in a craniocaudal direction
Term
What occurs if there is a homeobox gene mutation?
Definition
appendages in wrong locations
Term
By what time does hCG secretion begin?
Definition
within week 1 after implantation of blastocyst
Term
What happens during week two after fertilization?
Definition
differentiation into a bilaminar disk (epiblast and hypoblast); two cavities have formed (amniotic cavity and yolk sac); two components to placenta (cytotrophoblast, syncytiotrophoblast)
Term
What happens during week three of fetal development?
Definition
trilaminar disc; gastrulation; primitive streak, notochord, mesoderm and its organization, and neural plate begin to form
Term
When does the neural tube close?
Definition
week 4
Term
WHen does the heart begin to beat?
Definition
week 4
Term
When does the fetus start to move?
Definition
week 8
Term
When do fetal genitalia have male/female characteristics?
Definition
week 10
Term
What are the motor and sensory parts of the fetal spinal cord?
Definition
alar plate is dorsal (lateral) and sensory; basal plate is ventral (medial) and motor
Term
During what days does the fetus go from neural plate to neural tube?
Definition
day 18 to day 21
Term
When do the limb buds form?
Definition
week 4
Term
What is the primitive streak?
Definition
the epiblast (precursor to ectoderm) invaginates to form a primitive streak; cells from the primitive streak give rise to both intraembryonic mesoderm and part of the endoderm
Term
What is a craniopharyngioma?
Definition
benign rathke's pouch tumor with cholesterol crystals and calcifications
Term
Where embryologic tissue type does the lens of the eye come from?
Definition
surface ectoderm
Term
What embryologic tissue does the adenohypophysis come from?
Definition
surface ectoderm
Term
What tissue type do the sensory organs of the ear come from?
Definition
surface ectoderm
Term
What embryologic tissue type does olfactory epithelium come from?
Definition
surface ectoderm
Term
What tissues form from neuroectoderm?
Definition
brain (neurohypophysis, CNS neurons, oligodendrocytes, astrocytes, ependymal cells, pineal gland), retina, spinal cord
Term
Where do parafollicular C cells of the thyroid come from?
Definition
neural crest
Term
Where does the pia and arachnoid matter come from?
Definition
neural crest
Term
Where do ondontoblast come from?
Definition
neural crest
Term
Where do the bones of the skull come from?
Definition
neural crest
Term
What part of the heart is formed by neural crest?
Definition
aorticopulmonary septum
Term
Where do the lungs come from?
Definition
endoderm
Term
Where does the thymus come from?
Definition
endoderm
Term
What embryological tissue does the thyroid follicular cells come from?
Definition
endoderm
Term
What tissue type does the spleen come from?
Definition
mesoderm
Term
What tissue type does the eustachian tube come from?
Definition
mesoderm
Term
What tissue type does the skin dermis come from?
Definition
mesoderm
Term
What tissue type are the gonads derived from?
Definition
mesoderm
Term
What kinds of malformations result from mesoderm defects?
Definition
vertebral, anal atresia, cardiac, tracheoesophageal fistula, renal defects, limb defects
Term
What is the difference between aplasia and agenesis?
Definition
agenesis= absent organ due to absent primordial tissue; aplasia= absent organ despite present primordial tissue
Term
What are the teratogenic effects of alkylating agents?
Definition
absence of digits, multiple anomalies
Term
What are the effects of aminoglycosides on fetus?
Definition
cranial nerve VIII toxicity
Term
What are the effects of carbamazepine on a fetus?
Definition
NTDs, craniofacial defects, fingernail hypoplasia, developmental delay, IUGR
Term
What are the teratogenic effects of phenytoin?
Definition
fetal hydantoin syndrome: microcephaly, dysmorphic craniofacial features, hypoplastic nails and distal phalanges, cardiac defects, IUGR, mental retardation
Term
What are the teratogenic effects of valproate?
Definition
inhibition of maternal folate absorption--> NTDs
Term
What are the teratogenic effects of warfarin?
Definition
bone deformities, fetal hemorrhage, abortion, opthalmologic abnormalities
Term
What are the effects of cocaine on the fetus?
Definition
abnormal fetal development and fetal addiction; placental abruption
Term
What are the effects of smoking on the fetus?
Definition
preterm labor, placental problems, IUGR, ADHD
Term
What are the effects of maternal diabetes on the developing fetus?
Definition
caudal regression (anal atresia to sirenomelia), congenital heart defects, neural tube defects
Term
What are the effects of excess vitamin A on the fetus?
Definition
high ghigh risk for spontaneous abortions and birth defects (cleft palate and cardiac abnormalities)
Term
What are the effects of xrays on a fetus?
Definition
microcephaly, mental retardation
Term
What is teh mechanism by which alcohol is teratogenic?
Definition
inhibition of cell migration
Term
What are the specific anomalies associated with FAS?
Definition
developmental retardation, microcephaly, holoprosencephaly, facial abnormalities, limb dislocation, and heart and lung fistulas
Term
Describe the number of chorions/amnions for dizygotic twins.
Definition
dichorionic diamniotic
Term
Describe the number of chorions/amnions for monozygotic twins?
Definition
if splits during days 0-4= dichorionic diamniotic with either fused or separate placenta (25%); 4-8 days= monochorionic diamnionic (75%); 8-12 days= monochorionic monoamniotic (<1%); >13 days= monochorionic monoamniotic conjoined twins
Term
What is the purpose of beta hCG?
Definition
stimulate corpus luteum to secrete progesterone during first trimester
Term
What is the maternal component of the placenta?
Definition
decidua basalis (derived from endometrium; maternal blood in lacunae)
Term
What is the significance of a single umbilical artery?
Definition
congenital and chromosomal anomalies
Term
Where do the umbilical arteries connect to?
Definition
fetal internal iliac arteries to placenta
Term
Where does teh umbilical vein connect?
Definition
IVC to placenta
Term
What are the umbilical arteries and veins derived from?
Definition
allantois
Term
Where does the allantois come from and what does it form?
Definition
comes from the yolk sac in the third week and extends into the urogenital sinus; becomes the urachus, a duct between teh bladder and yolk sac
Term
What happens if the urachus does not obliterate?
Definition
patent urachus or vesicourachal diverticulum (outpouching of bladder)
Term
What is the viteline duct?
Definition
aka omphalomesenteric duct; connects the yolk sac to midgut lumen (obliterates in the 7th week)
Term
What is a vitelline fistula?
Definition
failure of duct to close leading to meconium discharge from the umbilicus
Term
What does the bulbus cordis give rise to?
Definition
right ventricle and smooth parts (outflow tract) of left and right ventricle
Term
What does the primitive ventricle form?
Definition
trabeculated left and right ventricle
Term
What structure does teh primitive atria form?
Definition
trabeculated left and right atrium
Term
What does the sinus venosus give rise to?
Definition
left horn= coronary sinus; right horn= smooth part of the right atrium
Term
What fetal structures give rise to the SVC?
Definition
right common cardinal vein and right anterior cardinal vein
Term
Describe the formation of the aorticopulmonary septum.
Definition
neural crest migration -> truncal bulbar ridges that spiral and fuse
Term
What heart defects are due to defective formation of the aorticopulmonary septum?
Definition
transposition of the great vessels, tetralogy of fallot, persistant TA
Term
Describe the formation of the interventricular septum?
Definition
muscular ventricular septum forms; opening is called interventricular foramen; AP septum meets and fuses with muscular ventricular sptum to form membranous interventricular septum, closing interventricular foramen
Term
What do the endocardial cushions do during heart development?
Definition
growth of endocardial cushions separates atria from ventricles and contributes to both atrial separationand membranous portion of the interventricular septum
Term
What forms the valve of the the foramen ovale/
Definition
remnant of septum primum
Term
What causes a patent foramen ovale?
Definition
excessive resorption of septum primum and/or secundum
Term
Where does fetal erythropoesis occur?
Definition
3-8 weeks= yolk sac; 6-30 weeks= liver; 9-28 wks= spleen; bone marrow= 28 weeks onward
Term
What are the globin chains that make up fetal hb?
Definition
2 alpha; 2 gamma
Term
Where does the ductus arteriosus connect?
Definition
aorta (distal to left subclavian) to branch of right and left pulmonary artery
Term
Closed foramen ovale is called...
Definition
fossa ovalis
Term
What causes closure of teh ductus arteriosus?
Definition
increase in O2 leads to decrease in prostaglandins, causing closure of ductus arteriosus
Term
Adult derivative of the umbilical vein?
Definition
ligamentum teres hepatis contained in the falciform ligament
Term
What are the derivatives of the umbilical arteries?
Definition
medial umbilical ligaments
Term
What is a derivative of the ductus arteriosus?
Definition
ligamentum arteriosum
Term
What is the adult derivative of the ductus venosus?
Definition
ligamentum venosum
Term
What is teh adult derivative of the allantois?
Definition
urachus-median umbilical ligament
Term
What does the telencephalon become?
Definition
wall= cerebral hemispheres; cavities= lateral ventricles
Term
What does the diencephalon become?
Definition
walls= thalamus; cavities= third ventricle
Term
What does the mesencphalon become?
Definition
walls= midbrain; cavities= aqueduct
Term
What does the metencephalon become?
Definition
walls= pons and cerebellum; cavities= upper part of fourth ventricle
Term
What does the myelencephalon become?
Definition
medulla and lower part of fourth ventricle
Term
What are the associated findings of anencephaly?
Definition
elevated AFP and polyhydramnios
Term
What is a chiari II malformation?
Definition
cerebella tonsillar herniation through foramen magnum with aqueductal stenosis and hydrocephaly; often presents with syringomyelia, thoraco-lumbar meningocele
Term
What is dandy walker syndrome?
Definition
large posterior fossa; absent cerebellar vermis with cystic enlargement of 4th ventricle; can lead to hydrocephalus and spina bifida
Term
What are teh symptoms of syringomyelia?
Definition
crossing fibersof spinothalamic tract are typically damaged first leading to "cape-like" biltareal loss of pain and temperature sensation in upper extremities with preservation of touch sensation
Term
Where is syringomyelia most commonly located?
Definition
C8 to T11
Term
Derivative of the first aortic arch?
Definition
part of the maxillary artery (branch of external carotid)
Term
What is the derivative of the second aortic arch?
Definition
stapedial artery and hyoid artery
Term
What are the derivatives of the third aortic arch?
Definition
common carotid artery and proximal part of internal carotid artery
Term
What is the derivative of the fourth aortic arch?
Definition
on left aortic arch; on right proximal part of right subclavian artery
Term
What are the derivatives of the sixth aortic arch?
Definition
proximal part of pulmonary arteries and (on left only) ductus arteriosus
Term
What vessels are close to the recurrent laryngeal nerves?
Definition
righ recurrent laryngeal loops around the branch point of the brachiocephalic artery into right common carotid and right subclavian; left recurrent laryngeal loops around ductus arteriosus
Term
What's another name from branchial clefts?
Definition
branchial grooves
Term
Which branchial aparatuses are derived from each type of embryonic tissue?
Definition
clefts/grooves= ectoderm; arches= mesoderm (muscles arteries) and neural crest (bones and cartilage); pouches= endoderm
Term
What are the branchial cleft derivatives?
Definition
first cleft develops into external auditory meatus; second through 4th forms the temporary cervical sinuses which are obliterated by proliferation of 2nd arch mesenchyme
Term
What are the derivatives of the first branchial arch?
Definition
meckel's cartilage; mandible, malleus, incus, sphenomandibular ligament
Term
What muscles are derived from teh first branchial arch?
Definition
muscles of mastication, myelohyoid, anterior belly of digastric tensor tympani, tensor veli palatini
Term
What are the nerves derived from teh first branchial arch?
Definition
CN V2 and V3
Term
What is Treacher Collins syndrome?
Definition
first arch neural crest fail to migrate leading to mandibular hypoplasia and facial abnormalities
Term
What are the cartilage derivatives of the second branchial arch?
Definition
richert's cartilage: stapes, styloid process, lesser horn of hyoid, stylohyoid ligament
Term
What are the muscular derivatives of the second branchial arch?
Definition
muscles of facial expression, stapedius, stylohyoid, posterior belly of digastric
Term
What nerves are derived from teh second branchial arch?
Definition
CN VII
Term
What are the cartilage derivatives of the third branchial arch?
Definition
cartilage; greater horn of the hyoid
Term
What are the muscular derivatives of the third branchial arch?
Definition
stylopharyngeus
Term
What are the nerves associated with the third branchial arch?
Definition
CN IX
Term
What is a congenital pharyngocutanous fistula?
Definition
persistance of third cleft and pouch causing a fistula between the tonsillar area and a cleft in the lateral neck
Term
What are the cartilage derivates of the 4-6 branchial arches?
Definition
thyroid, cricoid, arytenoids, corniculate, cuneiform
Term
What are the muscles of the 4-6 branchial arches?
Definition
fourth= most pharyngeal constrictors: cricothyroid, levator veli palatini
sixth= all intrinsic muscles of larynx except cricothyroid
Term
Which nerves ar derived from the fourth and sixth branchial arches?
Definition
fourth= CN X (superior laryngeal branch)
sixth= CN X (recurrent laryngeal branch)
Term
Which branchial arches form the tongue?
Definition
branchial arch 1 makes the anterior 2/3rds of the tongue; branchial arches 4-6form the posterior 1/3 of the tongue
Term
Which branchial arch has no derivatives?
Definition
5
Term
What are teh derivatives of the first branchial pouch?
Definition
middle ear cavity, eustachian tube, mastoid air cells
Term
What are the derivatives of the second branchial pouch?
Definition
epithelial lining of palatine tonsil
Term
What are teh derivatives of the third branchial pouch?
Definition
dorsal wings= inferior parathyroids; ventral wings= thymus
Term
What are the derivatives of the fourth branchial pouch?
Definition
dosral wings develop into superior parathyroids
Term
The parafollicular cells of the thyroid are derived from what pouches?
Definition
neural crest cells associated with the fourth and fifth pharyngeal pouches
Term
What supplies taste sensation to the tongue?
Definition
VII to teh anterior 2/3rds; IX for posterior 1/3; X for extreme posterior
Term
What nerves provide touch sensation to the tongue?
Definition
V3 for anterior 2/3rds; posterior 1/3 is IX; extreme posterior is X
Term
What nucleus in the brain mediates taste from the tongue?
Definition
solitary nucleus
Term
Which myotomes are the muscles of the tongue derived from?
Definition
occipital
Term
The thyroglossal duct may persisa as...
Definition
pyramidal lobe of thyroid
Term
What ishe foramen cecum?
Definition
normal remnant of the thyroglossal duct
Term
Where is the most common site of ectopic thyroid tissue?
Definition
tongue
Term
What are the symptoms of a thyroglossal duct cyst?
Definition
midline neck; moves with swallowing
Term
Cleft lip is due to a failure of fusion of what structures?
Definition
maxillary and medial nasal processes (formation of primary palate)
Term
A cleft palate results from failure of fusion of what structures?
Definition
lateral palatine processes, nasal septum, and/or median palatine process (formation of secondary palate)
Term
What abdominal wall defect is associated with protrussion of the liver?
Definition
omphalocele (rarely associated with gastroschisis)
Term
Failure of rostral wall closure=
Definition
sternal defects
Term
Failure of lateral fold closure-
Definition
omphalocele, gastroschisis
Term
Failure of caudal fold closure=
Definition
bladder exstrophy
Term
What is apple peel atresia?
Definition
jejunal, ileal, colonic atresia that is due to vascular accident
Term
What part of the gut herniates through the umbilical ring?
Definition
mid gut
Term
When does the midgut herniate? return?
Definition
6th week; 10th week
Term
The midgut rotates around the ____ while it herniates during development.
Definition
SMA
Term
What is tyep A trachioesophageal fistula?
Definition
stricture in esophagus
Term
what is type B tracheoesophageal fistula?
Definition
proximal esophagus is attached to trachea and distal esophagus is a blind tube
Term
What is type C tracheoesophageal fistula?
Definition
proximal esophagus ends in a blind pouch and distal esophagus connects to trachea
Term
When does pyloric stenosis present?
Definition
2 weeks
Term
What is the incidence of congenital pyloric stenosis?
Definition
1/600 (first born males)
Term
What embryologic structure is the pancreas derived form?
Definition
foregut
Term
What does the ventral pancreatic bud form?
Definition
uncinate process
Term
What does the dorsal pancreatic bud form?
Definition
body, tail, isthmus, and accessory pancreatic duct
Term
What forms the main pancreatic duct?
Definition
dorsal and ventral pancreatic buds contribute to the main pancreatic duct
Term
What forms the head of the pancreas?
Definition
both the ventral and dorsal pancreatic bud
Term
What is an annular pancreas?
Definition
ventral bud abnormally encircles second part of duodenum; forms a ring of pancreatic tissue that may cause duodenal narrowing
Term
What is pancreas divisum?
Definition
ventral and dorsal parts fail to fuse at 8 weeks
Term
Where does teh spleen arise from?
Definition
dorsal mesntery and hence is of mesodermal origin but supplied by celiac artery
Term
When does the pronephros degenerate?
Definition
week 4
Term
During what time does the mesonephros function as an interim kdiney?
Definition
1st trimeseter
Term
When does the metanephros first appear?
Definition
5th week of gestation
Term
When is nephrogenesis complete?
Definition
by 32-36 WGA
Term
When is the ureteric bud structures fully canalized?
Definition
10th week
Term
What induces differentiation of metanephric mesenchyme?
Definition
ureteric bud
Term
where does the ureteric bud derivatives end and mesonephric derivatives begin?
Definition
ureteric bud forms up through collecting duct; mesonephros forms down through distal tubules
Term
What is the most common site of urinary obstruction in fetuses?
Definition
ureteropelvic junction (last to canalize)
Term
What causes potter's syndrome?
Definition
malformation sof the ureteric bud
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