Embryology Flashcards
elevated AFP and acetylcholinesterase in amniotic fluid indicates? which can also be found in maternal serum?
neural tube defects-failed fusion of neurospores (at anterior or posterior ends) leads to communication between spinal canal and amniotic cavity. AFP
failure of fusion at caudal (posterior) end of neural tube? rostral (anterior) end?
spinal bifida occulta, meningocele, meningomyelocele
encephalocele (herniation of brain tissue through cranial defect) and anencephaly (total absence of brain and calvarium)
name some clinical features of hypothyroidism in children
lethargy, feeding problems, constipation, macroglossia, umbilical hernia, large fantanels, dry skin, hypothermia, and prolonged jaundice.
problems with differentiation of cells can lead to
leukemias
how formation of mature thyroid occur?
when thyroid follicles (from an evagination of the pharyngeal epithelium) and parafollicular C-cells (from the ultimobrachial bodies) fuse together
ultimobrachial body-embryological structure that gives rise to the calcitonin-producing cells—also called parafollicular cells or C cells—of the thyroid gland. In humans, this body is a derivative of the ventral recess of the fourth pharyngeal pouch
intracrainial calcified cystic mass filled with thick yellow-brownish fluid that is rich in cholesterol
craniopharyngiomas
the lecithin-sphingomyelin is a marker of?
fetal lung maturity
what hormone helps accelerate fetal lung maturation?
cortisol from fetal adrenal gland and cortisol from mother
what is role of hCG during preganncy? oxytocin? progesterone?
resembles LH, FSH, and TSH- functions to support the corpus lutem so that there is enough progesterone to maintain pregancy
- stimulates myometrial contraction- levels are stable throughout preg, receptor expression increases in myometrium before delivery
- preparing endometrium for implantatoin
name one of the most common causes of elevated AFP levels. decreased level?
underestimation of gestational age (confirm with ultrasound)
Downs syndrome
triple test mesaures. abnormal levels of each hormone indicate?
AFP, hCG, and estriol
AFP- underestimation of gestational age (increased); Downs (decreased)
estriol-placental insufficiency (decreased)
hCG- multiple gestation, hydatidiform mole, and choriocarcinoma (increased)
urachus vs allantosis vs yolk stalk
urachus is remnant of the allantois that connects the bladder to the yolk sack. the allantois connects the urogenital sinus to the yolk sac. upper part of urogenital sinus becomes the bladder.
-aka vitelline duct, aka omphalomesenteric duct-connects yolk sac to midgut lumen
patent urachus
vesicourachal diverticulium
urachal sinus
urachal cyst
connection between umbilicus and bladder- urine discharge from umbilicus
failure to close part of urachus close to bladder-outpouching of apex of bladder, asymptomatic
failure to close distal part of urachus close to umbilicus-periumbilical tenderness and purulent discharge b/c of reccurrent infections
failure of central portion of urachus to obiterate- fluid filled structure b/t obilterated ends of urachus, asymptomatic
persistent yolk stalk
Meckel diverticulum
aka vitelline fistula, connect small intestine to umbilicus. meconium discharge from umbilicus
-incomplete obliteration of vitelline duct at proximal end - outpouching of small intestine
omphalocele vs gastroschisis
incomplete closure of anterior abdominal wall-viscera protrude through umbilicus, covered by peritoneum
-inadequate enlargement of peritoneal cavity-viscera protrude next to umbilicus not covered by peritoneum
congenital abnormality seen with valproate in pregnant women. why?
neural tube defects. it inhibits intestinal folic aicd absorption
congenital abnormality associated with Turner’s syndrome and bicuspid valves
coarctation of aorta
congenital abnormality associated with Downs syndrome
duodenal atresia-bilious vomiting without abdominal distention
congenital abnormality associated with Potter’s syndrome
renal agenesis
failure of paramesonephric ducts to fuse leads to? normal fusion creates what 4 structures in females? what happens to p. duct in males?
fusion leads to uterine tubes, uterus, cevix, and superior 1/3 of vagina formation. failure results in bicornuate uterus (partial fusion) or uterus didelphys (no fusion 2 of everything).
-p. ducts involute in males leaving vestige appendices of testes
mesonephric duct forms what in females? in males?
gartner’s ducts
efferent ductules-carry sperm from testies to epididymis SEED (seminal vesicles, epididymis, ejactulatory duct, ductus deferens)
urethral folds fuse to form what in males? females?
urethra in both
improper fusion can lead to hypospadias in males
pharyngeal arch it’s associated aortic arch, CN, and key aortic arch derivatives
1,2,3,4,5,5
1-1, trigeminal nerve V, maxillary artery (portion)
2-2, facial VII, stapedial artery (regresses)
3-3, glossopharyngeal IX, CCA, proximal ICA
4-4, superior laryngeal branch of vagus (X), true aortic arch, subclavian arteries
5-5, obliterated, obliterated
6-6, reccurrent laryngeal branch of vagus (X), pulmonary arteries, ductus arteriosus
Hirschsprung’s vs bifid ventral pancreatic bud
both present with bilious vomiting. Hirschsprung’s is associated with a mutation in RET gene and associated with Downs (abnormal karyotype) and usually has some kind of rectum presentation (constricted sphincter or bleeding) b/c stenosis id below ligament of trite (duodenal-jejunum junction).
whereas BVB is just a fancy name for annular pancreas-has a normal karyotype and no rectum presentation.
bilious vomiting indicates that obstruction is where?
distal to entrance of common bile duct into 2nd part of duodenum, not pyloric stenosis or tracheoesophageal fistula
foramen cecum
thyroid gland develops from the thyroid diverticulum which forms the midline near the foramen cecum.
congenital diaphragmatic hernia def and mc location, organ affected that leads to death.
herniation of abdominal contents into pleural cavity due to failure of pleuroperitoneal to develop properly. found on left posterolateral side and causes pulmonary hypoplasia.
relationship between aorta, and iliac arteries, and femoral arteries
aorta becomes common iliac artery, which becomes external and internal iliac arteries. external iliac arteries become femoral arteries which pass inferiorly to inguinal ligaments
right and left umbilical arise from? and give rise to?
internal iliac arteries and give rise to medial umbilical ligaments
at what stage are premenopausal women eggs at? what occurs during this stage?
prophase of meiosis I, DNA has generated double-stranded chromosomes that condense and migrate to the centromeres.
meningocele vs meningomyelocele
M-Normal AFP, just meninges not spinal cord herniate
MM-elevated AFP, both meninges and spinal cord herniate
teratogenic effect of mumps in 1st ttrimester
aqueductal stenosis-located in midbrain
systolic ejection murmur heard in left midsternal border and a wide, fixed split of S2. presents how?
atrial septal defect- usually occurs in septum secundum. exercise intolerance.
persistant foramen ovale vs atrial septal defect
- usually asymptomatic, very small and will go away spontaneously, septum missing tissue
- septum not fusing, causes exercise intolerance, presents late childhood
VSD vs ASD vs PDA vs aortic valve stenosis murrur
VSD- harsh and holosystolic at left lower sternal border
ASD-systolic ejection murmur
PDA-machine-like continuous across diastole and systole
aortic-systolic ejection murmur with ejection click
spleen develops from which embryonic layer?
mesoderm-mass of mesenchyal cells located between layers of dorsal mesogastrium, it is not a foregut structure and no derived from endodermal epithelium
celiac artery supplies blood to? arises at what level?
all foregut organs and spleen, arises at T12
gastrochisis def, elevated levels of? layers not covering viscera?
ventral body defect (incomplete fusion of lateral body folds) that presents with herniation of abdominal viscera (not covered by amnion or peritoneum) elevated levels of AFP.
name some causes of enlarged tongue
Congenital hypothyroidism (Cretinism): also look for mental retardation, dwarfism, pott belly, ….etc
Down syndrome: importantly to note that it’s the small oral cavity that results in the protruding tongue not a real big tongue.
Amyloidosis: It’s wise to remember that’s the tongue is a good site for biopsy when diagnosing amyloidosis.
Acromegaly: As all other organs get enlarged by the excessive growth hormone.
Hurler syndrome: Also notably the course facial features.
Beckwith Wiedamann Syndrome: Also hemihypertrophy, macrosomia and insulinoma.
Of note, three of these conditions are also associated with peri-umbilical hernia (Down, Cretinism, and BWS)!
tracheoesophageal fistula- def, associations (2), presentation (4)
abnormal communication between trachea and esophagus, caused by malformation of tracheoesophageal septum
associatedwith esophageal atresia and polyhydramnios
results in immediate vomiting after feeding, copious frothy secretions and gagging
Meckel diverticulum occurs when, where, complicaiton, diagnose
remnant of vitelline duct persist, forming a blind pouch
located in distal ilieum 30 inches of the ileocecal valve
can become inflammed if it contains ectopic pancreatic tissue or gastric mucosa which may produce ulceration and classic clincal presentation of massive painless rectal bleeding
diagnose with radioscope (technetium (99m Tc)) scan
describe mekel’s rules of 2s
2 inches long, withing 2 feet of ileocecal valve, 2% of pop, presents within 1st 2yrs of life, contains 2 type of epithelium gastric and pancreatic
DiGeorge Syndrome- def, abnormality, presentation
abnormal neural crest cell migration
pharyngeal pouches 3 and 4 fail to differentiate into parathyroid,glands, thymus, cardiac, and facial structures
presents with immunological problems, hypocalcemia, cardiovascular defects, abnormal ears, and micrognathia
intestinal atresia vs duodenal atresia
both have bilious vomiting
intestinal- multiple air filled sacs- caused by intrauterine vascular accident with ischemic necrosis of bowel
duodenal- double bubble (proximal stomach distention), caused by recanalization failure, early clue is polyhydraminos
duodenal atresia- pathology, clinical features, associations, similar presentation to?
caused by failure of recanalization, early bilious vomiting, double-bubble picture, associated with Downs, similar presentation to annular pancreas
neural crest cells give rise to
PNS (drg, CNs, celiac ganglion, Schwann cells, ANS) melanocytes, chromaffn cells of adrenal medulla, parafollicular (C) cells of thyroid, pia and arachanoid, bones of skull, odontoblasts, aorticopulmonary septum
HIrschsprung disease-def, and embryonic layer
results from failure of neural crest cells to form myenteric plexus in the sigmoid colon and rectum
Androgen insensitivity syndrome-genotype, phenotype, 1 sexual and 2 sexual characteristics
male genotype 46XX (develops testes), with female phenotype (external genitala with rudimentary vag and no uterus or fallopian tubes)
testes are usually in abdominal or inguinal canal and should be removed to prevent malignant tumor formation
persistant truncus arterious-def, also presents with what septal defect
failure of conotruncal ridges to form AP septum, since ridges also participate in formation of membranous interventricular septum, at VSD will also be evident cardiac anomaly (C) in (22q11 deletion syndromes-CATCH-22)
surface ectoderm gives rise to
adenohypophysis (from Rathke pouch), lens of eye, epithelial linings of oral cavity, sensory organs of ear, and olfactory epithelium, epidermis, anal canal below pectinate line, parotid, sweat, and mammary glands
neuroectoderm gives rise to
brain (neurohypophysis, CNS neurons, oligodendrocytes, astrocytes, ependymal cells, pineal gland), retina, optic nerve and spinal cord
mesoderm gives rise to
3heart- cardiovascular structures, lymphatics, blood
3 layers-serous lining of body cavity (i.e. peritoneum), wall of gut tube, dermis
3 bone-muscles, bone, connective tissue
3 organs-spleen, kidney, adrenal cortex
3 genitals-testes, ovaries, vagina
notochord gives rise to
nuclei pulposus of the intervertebral disks
endoderm gives rise to
gut tube epithelium (anal canal above pectinate line), most of urethra (from urogenital sinus) luminal epithelial derivatives (lungs, liver, gallbladder, pancreas, eustachian tube, thymus, parathyroid, thyroid follicular cells)
teratomas occur where in infants, embryonic layer?
mc location in sacrococcygeal region
derived from all three germ layers (primitive streak-b4 the germ layers form)
