Repro II

Question 1

dizygotic twin

Answer 1

from 2 eggs - fertilized 2 different sperm - 2 zygote

2 separate amniontic sac and 2 separate placenta

always dichorion diamnion

Question 2

monozygotic twin

Answer 2

from 1 fertilized egg - splits to 2 zygote

degree of separation - depend on when split ocurs

0-4 days - dichorionic diamnionic
4-8 days - MC - monochorion diamnion
8-12 days - monochorion monoamnion
more than 13 days - monochorion/monoamnion - conjoined

Question 3

MC twins

Answer 3

monochorion
diamniontic

split - 4-8 days

Question 4

cytotrophoblast

Answer 4

inner layer chorion villi

make cells

Question 5

syncytiotrophoblast

Answer 5

outer layer chorionic villi

secrete hCG

stimulate corpus luteum to secrete progesterone during first trimester

lack MHC 1 - chance of attack by maternal immunity

Question 6

decidua basalis

Answer 6

from endometrium - maternal blood in lacunae

Question 7

placena components

Answer 7

fetal - cytotrophoblast, syncytiotrophoblast

maternal - decidua basalis

Question 8

umbilical cord

Answer 8

2 umbilical aa - deox blood from mother
1 umbilical v - O2 blood to fetus

single artery - congenital and chromosome abnormali

derived - from allantois

Question 9

urachus

Answer 9

3rd week - yolk sac form from allantois

extend into urogenital sinus

becomes urachus - duct between fetal bladder and yolk sac

Question 10

patent urachus

Answer 10

urine from umbilicus

Question 11

urachal cyst

Answer 11

fluid filled cavity

infection and adenocarcinoma

Question 12

vesicourachal diverticulum

Answer 12

outpouch of bladder

Question 13

vitelline duct

Answer 13

7th week - obliteration of vitelline duct

-connect yolk sac to midgut

Question 14

vitelline fistula

Answer 14

vitelline duct fail close - meconium discharge umbilicus

Question 15

meckel diverticulum

Answer 15

partial close vitelline duct

may have gastric/pancreatic tissue

Question 16

1st aortic arch

Answer 16

max artery - branch external carotid

Question 17

2nd aortic arch

Answer 17

stapedial and hyoid artery

Question 18

3rd aortic arch

Answer 18

common carotid a

proximal internal carotid a

Question 19

4th aortic arch

Answer 19

left - aortic arch

right - prox right subclavian a

Question 20

6th aortic arch

Answer 20

prox pulmonary arteries

left only - ductus arteriosus

Question 21

left recurrent laryngeal n

Answer 21

caught by ductus arteriosus (6th arch)

ductus arteriosus - becomes ligamentum arteriosus

Question 22

right recurrent laryngeal n

Answer 22

loops around subclavian artery

Question 23

branchial apparatus

Answer 23

aka pharyngeal apparatus

cleft - outside - ectoderm
arch - outside - mesoderm and neural crest
pouch - inside - endoderm

Question 24

1st branchial cleft

Answer 24

external auditory meatus

Question 25

2-4 branchial cleft

Answer 25

temporary cervical sinus - obliterated by 2nd arch mesenchyme proliferation

Question 26

persistant cervical sinus

Answer 26

branchial cleft cyst

-lateral neck

Question 27

1st branchial arch

Answer 27

mandible
malleus, incus
sphenomandibular ligament

muscle of mastication
ant belly digastric
tensor tympani
tensor veli palatini

nerve - 5b and 5c

Question 28

treacher collins syndrome

Answer 28

1st arch neural crest fail migrate
-mandibular hypoplasia
facial abnormalities

Question 29

2nd branchial arch

Answer 29

reichert cartilage

• stapes
• styloid
• lesser horn hyoid
• stylohyoid ligament

muscle facial expression

stapedius
stylohyoid
platysma
post belly digastric

nerve - 7

Question 30

congenital pharyngocutaneous fistula

Answer 30

persistence of cleft/pouch

fistula between tonsillary area and lateral neck

Question 31

3rd branchial arch

Answer 31

cartilage - greater horn hyoid

stylopharyngeus

nerve - 9 - glossopharygeal

Question 32

4-6 branchial arches

Answer 32

thyroid, cricoid, arytenoid, corniculate, cuneiform cartilages

4th - pharyngeal constrictors, cricothyroid, levator veli palatini
-nerve -10 - superior laryngeal branch

6th - all intrinsic muscle of larynx (not cricothyroid)
-nerve - 10 - recurrent laryngeal branch

Question 33

branchial arch 3 and 4

Answer 33

posterior 1/3 tongue

Question 34

branchial arches

Answer 34

1 chew - 5b anc 5c
2 smile - 7
3 swallow stylishly (stylopharyngeus) - 9
4 swallow - 10 - superior laryngeal
6 speak - 10 - recurrent laryngeal