Embryology

Question 1

elevated AFP and acetylcholinesterase in amniotic fluid indicates? which can also be found in maternal serum?

Answer 1

neural tube defects-failed fusion of neurospores (at anterior or posterior ends) leads to communication between spinal canal and amniotic cavity. AFP

Question 2

failure of fusion at caudal (posterior) end of neural tube? rostral (anterior) end?

Answer 2

spinal bifida occulta, meningocele, meningomyelocele

encephalocele (herniation of brain tissue through cranial defect) and anencephaly (total absence of brain and calvarium)

Question 3

name some clinical features of hypothyroidism in children

Answer 3

lethargy, feeding problems, constipation, macroglossia, umbilical hernia, large fantanels, dry skin, hypothermia, and prolonged jaundice.

Question 4

problems with differentiation of cells can lead to

Answer 4

leukemias

Question 5

how formation of mature thyroid occur?

Answer 5

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

Question 6

intracrainial calcified cystic mass filled with thick yellow-brownish fluid that is rich in cholesterol

Answer 6

craniopharyngiomas

Question 7

the lecithin-sphingomyelin is a marker of?

Answer 7

fetal lung maturity

Question 8

what hormone helps accelerate fetal lung maturation?

Answer 8

cortisol from fetal adrenal gland and cortisol from mother

Question 9

what is role of hCG during preganncy? oxytocin? progesterone?

Answer 9

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

Question 10

name one of the most common causes of elevated AFP levels. decreased level?

Answer 10

underestimation of gestational age (confirm with ultrasound)

Downs syndrome

Question 11

triple test mesaures. abnormal levels of each hormone indicate?

Answer 11

AFP, hCG, and estriol
AFP- underestimation of gestational age (increased); Downs (decreased)
estriol-placental insufficiency (decreased)
hCG- multiple gestation, hydatidiform mole, and choriocarcinoma (increased)

Question 12

urachus vs allantosis vs yolk stalk

Answer 12

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

Question 13

patent urachus
vesicourachal diverticulium
urachal sinus
urachal cyst

Answer 13

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

Question 14

persistent yolk stalk

Meckel diverticulum

Answer 14

aka vitelline fistula, connect small intestine to umbilicus. meconium discharge from umbilicus
-incomplete obliteration of vitelline duct at proximal end - outpouching of small intestine

Question 15

omphalocele vs gastroschisis

Answer 15

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

Question 16

congenital abnormality seen with valproate in pregnant women. why?

Answer 16

neural tube defects. it inhibits intestinal folic aicd absorption

Question 17

congenital abnormality associated with Turner’s syndrome and bicuspid valves

Answer 17

coarctation of aorta

Question 18

congenital abnormality associated with Downs syndrome

Answer 18

duodenal atresia-bilious vomiting without abdominal distention

Question 19

congenital abnormality associated with Potter’s syndrome

Answer 19

renal agenesis

Question 20

failure of paramesonephric ducts to fuse leads to? normal fusion creates what 4 structures in females? what happens to p. duct in males?

Answer 20

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

Question 21

mesonephric duct forms what in females? in males?

Answer 21

gartner’s ducts
efferent ductules-carry sperm from testies to epididymis SEED (seminal vesicles, epididymis, ejactulatory duct, ductus deferens)

Question 22

urethral folds fuse to form what in males? females?

Answer 22

urethra in both

improper fusion can lead to hypospadias in males

Question 23

pharyngeal arch it’s associated aortic arch, CN, and key aortic arch derivatives
1,2,3,4,5,5

Answer 23

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

Question 24

Hirschsprung’s vs bifid ventral pancreatic bud

Answer 24

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.

Question 25

bilious vomiting indicates that obstruction is where?

Answer 25

distal to entrance of common bile duct into 2nd part of duodenum, not pyloric stenosis or tracheoesophageal fistula

Question 26

foramen cecum

Answer 26

thyroid gland develops from the thyroid diverticulum which forms the midline near the foramen cecum.

Question 27

congenital diaphragmatic hernia def and mc location, organ affected that leads to death.

Answer 27

herniation of abdominal contents into pleural cavity due to failure of pleuroperitoneal to develop properly. found on left posterolateral side and causes pulmonary hypoplasia.

Question 28

relationship between aorta, and iliac arteries, and femoral arteries

Answer 28

aorta becomes common iliac artery, which becomes external and internal iliac arteries. external iliac arteries become femoral arteries which pass inferiorly to inguinal ligaments

Question 29

right and left umbilical arise from? and give rise to?

Answer 29

internal iliac arteries and give rise to medial umbilical ligaments

Question 30

at what stage are premenopausal women eggs at? what occurs during this stage?

Answer 30

prophase of meiosis I, DNA has generated double-stranded chromosomes that condense and migrate to the centromeres.

Question 31

meningocele vs meningomyelocele

Answer 31

M-Normal AFP, just meninges not spinal cord herniate | MM-elevated AFP, both meninges and spinal cord herniate

Question 32

teratogenic effect of mumps in 1st ttrimester

Answer 32

aqueductal stenosis-located in midbrain

Question 33

systolic ejection murmur heard in left midsternal border and a wide, fixed split of S2. presents how?

Answer 33

atrial septal defect- usually occurs in septum secundum. exercise intolerance.

Question 34

persistant foramen ovale vs atrial septal defect

Answer 34

- usually asymptomatic, very small and will go away spontaneously, septum missing tissue - septum not fusing, causes exercise intolerance, presents late childhood

Question 35

VSD vs ASD vs PDA vs aortic valve stenosis murrur

Answer 35

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

Question 36

spleen develops from which embryonic layer?

Answer 36

mesoderm-mass of mesenchyal cells located between layers of dorsal mesogastrium, it is not a foregut structure and no derived from endodermal epithelium

Question 37

celiac artery supplies blood to? arises at what level?

Answer 37

all foregut organs and spleen, arises at T12

Question 38

gastrochisis def, elevated levels of? layers not covering viscera?

Answer 38

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.

Question 39

name some causes of enlarged tongue

Answer 39

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)!

Question 40

tracheoesophageal fistula- def, associations (2), presentation (4)

Answer 40

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

Question 41

Meckel diverticulum occurs when, where, complicaiton, diagnose

Answer 41

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

Question 42

describe mekel's rules of 2s

Answer 42

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

Question 43

DiGeorge Syndrome- def, abnormality, presentation

Answer 43

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

Question 44

intestinal atresia vs duodenal atresia

Answer 44

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

Question 45

duodenal atresia- pathology, clinical features, associations, similar presentation to?

Answer 45

caused by failure of recanalization, early bilious vomiting, double-bubble picture, associated with Downs, similar presentation to annular pancreas

Question 46

neural crest cells give rise to

Answer 46

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

Question 47

HIrschsprung disease-def, and embryonic layer

Answer 47

results from failure of neural crest cells to form myenteric plexus in the sigmoid colon and rectum

Question 48

Androgen insensitivity syndrome-genotype, phenotype, 1 sexual and 2 sexual characteristics

Answer 48

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

Question 49

persistant truncus arterious-def, also presents with what septal defect

Answer 49

``` 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) ```

Question 50

surface ectoderm gives rise to

Answer 50

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

Question 51

neuroectoderm gives rise to

Answer 51

brain (neurohypophysis, CNS neurons, oligodendrocytes, astrocytes, ependymal cells, pineal gland), retina, optic nerve and spinal cord

Question 52

mesoderm gives rise to

Answer 52

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

Question 53

notochord gives rise to

Answer 53

nuclei pulposus of the intervertebral disks

Question 54

endoderm gives rise to

Answer 54

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)

Question 55

teratomas occur where in infants, embryonic layer?

Answer 55

mc location in sacrococcygeal region | derived from all three germ layers (primitive streak-b4 the germ layers form)