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Flashcards in Embryo Deck (30):

SHH genes codes for/defect caused

A=P patterning
@ base aka near beginning of developing limbs
Defect: holoprosencephaly


Wnt 7 genes codes for

Dorsal-ventral organization
@ end of develpoing limb


FGF genes codes for/defect caused

Stim mitosis of mesoderm underneath - lengthen limbs
At end of developing limb
FGF3 mutation = achondroplasia


HOX genes codes for/defect caused

Canio-caudal organization
Mutated - appendage in wrong location + syn/poly dactyly
Excess vit A increases this risk


When does B hCG start getting excreted? When do hearts/lung start to beat? What is the period when the fetus is most susceptible to damage by teratogens

Wk 1 - B hCG, when embryo implants at blastocyst
Wk 3-8 organs forming so most at risk for teratogens
Wk 4 fetal heart and lung development starts (4 chambers of the heart, wk 4)


Agenesis vs aplasia vs hypoplasia

Agen = no organ b/c precursor wasn't there
Aplasia = precursor but no end tissue
Hypo = precursor present but incomplete organ


Deformation vs malformation

Deform - extrinsic insult, often temporary and recoverable
Mal form - intrinsic disrupt probs wk 3-8



Disrupt = 2ary breakdown to normal tissue (amniotic band causing fingers not to form)
Sequence - 1 problem, many defects (kidneys -> potter)


What do high levels of hCG mean: both in a preg + diseases that have this

Multiple gestations
Downs: ↑hCG + inhibin, ↓AFP + estriol
Hydatidiform moles


What do low levels of hCG mean (diseases)

Ectopic/failing preg
Edwards - ↓hCG, PAPP-A, AFP, estriol, inhibin A
Trisomy 18 due to meiotic nondysjxn - low set ears, clenched hands w/ overlap fingers, small jaw, rocker bottom feet, large occiput)
Patau = low on everything
Trisomy 13, cleft lip.palate, holoprosencephaly, polydactyly, cutis aplasoa


1st aortic arch turns into

Part maxillary art (branch ext carotid)


2nd aortic arch turns into

Stapedial artery (to stapedius muscle that is controlled by CN7 for noise dampening)


3rd aortic arch turns into

Common carotid
Part int carotid art
"C is the 3rd letter in alphabet"


4th aortic arch turns into

L: aortic arch
R: part R subclavian
"4th arch gives rise to art that feed the 4 limbs)


6th aortic arch turns into (yes 5th degrades)

Ductus arteriosis


What is the tissue derivative of the brachial clefts? What does the first cleft develop into? What is the significance of a brachial cleft cyst?

1st cleft -> ext auditory meatus (aka ear canal)
Brachial cleft cyst = *lateral* neck that does NOT move with swallowing
Vs thyroglossal duct cyst = *medial* and moves when swallow


What is the tissue derivative of the branchial pouches? What do pouches 1-4 turn into?

"Ear, tonsils, bottom - to - top"
1: ear structures
2: tonsils - epi lining
3: bottom = dorsal wings = inf PT; to = thymus
4: top = sup PT
**These are the structures damaged w/ DiGeorge - thymus + PT (3rd + 4th)


What tissue is the derivative of the branchial arches? Describe what arches 1-4 turn into

Mesoderm = muscles + arteries
Neural crest = bones + cart
"When at McDonald's w/ golden ARCHES, kids first CHEW, then SMILE, then SWALLOW STYLishly, or SIMPLY SWALLOW and then SPEAK"
1: muscles of mastication + innervation of V2 and V3, bones with M - maxilla, zygoMatic arch....
2: CN7 = smile/facial expression + associated muscle, stapes, styloid process, stapedius, platySma...
3: stylopharyngeus innervated by CN 9
4: CN 10 = swallow and speak, most throat/voice bones


Pierre Robin sequence

Problems w/ branchial arches 1 + 2
Micrognathia ** small jaw
Cleft palate
Airway conduction


Treacher Collins syndrome

Neural crest dysfxn
Mandibular hypoplasia
Facial abnormalities (very weird looking)


Describe how male genitals evolve

1. SRY @ Y chromosome -> TDF = testes det factor
2. Sertoli cells -> Mull inhib factor -> suppress paramesonephric/Mullerian ducts
Sertoil cells will later produce inhibit B when stim by FSH
3. Leydig cells -> androgens = promote mesonephric/Wolffian development
This makes sense since T from Leydig cells will create the internal male structures and DHT (from T) will create the external


What is the male remnant of the mullerian ducts?

Appendix testes


What is the female remnant of the wolffian ducts

Gartner duct


What happens if XY doesn't have sertoli cells and thus no mullerian inhibiting factor?

Leydig still work - both M int + ext
F int b/c mullerian ducts form


M + F versions of genital tubercle

Clitoris // glans
Vestibular bulbs // corpus cavernosum + spongiosum


M + F versions of urogenital sinus

Bartholin glands // bulbourethral glands
Urethral glands // prostate


M + F versions of urogenital folds

Labia minora // shaft penis


M + F versions of labioscrotal swelling

Labia majora // scrotum


What structure fails to fuse creating uterine cavity abnormalities?

Paramesonephric (mullerian) ducts
Normal -> septate -> bicornuate (incomplete) -> didelphys (complete failure)


What does the gubernaculum form in M vs W

M - gubernaculum anchors tests in scrotum
1. Ovarian ligament (attaches ovaries to uterus)
2. Round ligament of uterus (anchors uterus to labia majora)