Embryo

Question 1

SHH genes codes for/defect caused

Answer 1

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

Question 2

Wnt 7 genes codes for

Answer 2

Dorsal-ventral organization

@ end of develpoing limb

Question 3

FGF genes codes for/defect caused

Answer 3

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

Question 4

HOX genes codes for/defect caused

Answer 4

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

Question 5

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

Answer 5

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)

Question 6

Agenesis vs aplasia vs hypoplasia

Answer 6

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

Question 7

Deformation vs malformation

Answer 7

Deform - extrinsic insult, often temporary and recoverable

Mal form - intrinsic disrupt probs wk 3-8

Question 8

Disruption

Sequence

Answer 8

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

Question 9

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

Answer 9

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

Question 10

What do low levels of hCG mean (diseases)

Answer 10

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

Question 11

1st aortic arch turns into

Answer 11

Part maxillary art (branch ext carotid)

Question 12

2nd aortic arch turns into

Answer 12

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

Question 13

3rd aortic arch turns into

Answer 13

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

Question 14

4th aortic arch turns into

Answer 14

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

Question 15

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

Answer 15

Ductus arteriosis

Question 16

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?

Answer 16

Extoderm
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

Question 17

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

Answer 17

Endoderm
“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)

Question 18

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

Answer 18

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

Question 19

Pierre Robin sequence

Answer 19

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

Question 20

Treacher Collins syndrome

Answer 20

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

Question 21

Describe how male genitals evolve

Answer 21

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

Question 22

What is the male remnant of the mullerian ducts?

Answer 22

Appendix testes

Question 23

What is the female remnant of the wolffian ducts

Answer 23

Gartner duct

Question 24

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

Answer 24

Leydig still work - both M int + ext

F int b/c mullerian ducts form

Question 25

M + F versions of genital tubercle

Answer 25

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

Question 26

M + F versions of urogenital sinus

Answer 26

Bartholin glands // bulbourethral glands | Urethral glands // prostate

Question 27

M + F versions of urogenital folds

Answer 27

Labia minora // shaft penis

Question 28

M + F versions of labioscrotal swelling

Answer 28

Labia majora // scrotum

Question 29

What structure fails to fuse creating uterine cavity abnormalities?

Answer 29

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

Question 30

What does the gubernaculum form in M vs W

Answer 30

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