embryology

Question 1

where do germ cells form? (germ cells give rise to the gametes of an organism that reproduces sexually)

Answer 1

Germ cells form within the yolk sac in the fetus and travel to the fetal midsection, where the reproductive organs form.

Question 2

lower 2/3 of vagina are formed from…

Answer 2

sinovaginal bulbs (vaginal plate, from urogenital sinus, which also forms the urinary bladder - endoderm)

Question 3

is the vagina ectoderm, mesoderm or endoderm

Answer 3

upper 1-2/3 from intermediate mesoderm
lower 1-2/3 from endoderm

Question 4

what is Ebstein’s anomaly

Answer 4

septal and posterior leaflets of the tricuspid valve are displaced downwards towards the apex of the right ventricle of the heart. (systolic murmur)

Question 5

congenital absence of vas deferens - percentage risk that this male has cystic fibrosis

Answer 5

80%

Question 6

neurulation happens on week three. When does the neural TUBE form from the neural groove?

Answer 6

day 25

Question 7

when does the anterior neuropore close?
when does the posterior neuropore close?

Answer 7

day 24 - 29
day 27 - 30
sources differ, but the point is that the posterior closes after the anterior

Question 8

when does fetal kidney start to produce urine

Answer 8

urine production begins by weeks 13-15

Question 9

Embryonic origin of trigone of bladder?

Answer 9

Mesonephric duct!!
In the classic view of bladder development the trigone originates from the mesoderm derived wolffian ducts while the remainder of the bladder originates from the endoderm derived urogenital sinus.

Question 10

where does the hepatic diverticulum bud from?

Answer 10

terminal end of the foregut (duodenum)

Question 11

what is the septum transversum?

Answer 11

a thick mass of cranial mesenchyme, formed in the embryo, that gives rise to parts of the thoracic diaphragm and the ventral mesentery of the foregut, and provides mesenchyme to become the capsule of the liver

Question 12

when does hepatic diverticulum (/liver bud) (endoderm) form

Answer 12

3rd week

Question 13

what does the hepatic diverticulum grow into?

Answer 13

septum transversum (mesoderm)

Question 14

from how many buds does the pancreas develop from?

Answer 14

2 - the ventral and dorsal pancreatic buds
they will be joined together (posteriorly) by the rotation of the stomach and the migration of the liver

Question 15

how prevalent are cardiac malformations in neonates?

Answer 15

1%

Question 16

when does the fetal ‘heart’ start beating?

Answer 16

22 days

Question 17

the most inferior horns of the primitive heart, which receives blood and puts it into the primitive atrium is called…

Answer 17

sinus venosus

Question 18

in the primitive heart, blood from the ventricle moves into the… and then into the…

Answer 18

bulbus cordis
paired aortic arches

Question 19

from which structure do the right ventricle and outflow portions of the RV and LV develop

Answer 19

bulbus cordis

Question 20

from which structure do the right atrium, SVC, IVC and coronary sinus develop

Answer 20

sinus venosus

Question 21

what does the primordial ventricle become?

Answer 21

LV

Question 22

what does the primordial atrium become?

Answer 22

LA + R+L auricles

Question 23

from which structure do the aorta and pulmonary artery develop?

Answer 23

aortic sac

Question 24

from which structure(s) does the foramen ovale develop?

Answer 24

ostium secundum and septum secundum

Question 25

patent foramen ovale is frequently asymptomatic until...

Answer 25

DVT --> stroke via foramen ovale or increased right-sided pressure e.g. scuba diving increasing preload, causing a shunt from L-->R

Question 26

what does the allantois become and when?

Answer 26

urachus 5th-7th week

Question 27

what forms the allantois and when?

Answer 27

yolk sac, week 3

Question 28

from week 4 - week 12, what performs filtration?

Answer 28

mesonephros (before the metanephros takes over with the actual kidney)

Question 29

which bits of the kidney form from the ureteric bud, and which from the metanephric blastema

Answer 29

ureteric bud forms collecting system from collecting duct to calyces, renal pelvis, ureter the metanephric blastema forms the excretory portion from the glomerulus to the DCT

Question 30

embryological origin of the bladder

Answer 30

trigone = metanephric ducts (mesoderm) rest of bladder = (endodermal) cloaca / urogenital sinus the part of the hindgut which is distal to the allantois is called the cloaca a urorectal septum grows down into the cloaca, forming a urogenital sinus (anterior to septum) continuous with the allantois, and a primitive rectum (posterior to septum).

Question 31

what is the ductus venosus between?

Answer 31

umbilical vein and IVC thereby allowing oxygenated blood from the placenta to BYPASS the liver

Question 32

what type of cells form from the mesenchymal cells?

Answer 32

Leydig cells (males) ovarian support stroma

Question 33

what type of cells form from the mesothelial cells?

Answer 33

Seminiferous tubulues (male) follicular cells

Question 35

at what stage of development do the Mullerian ducts form the internal female genitalia?

Answer 35

week 8 - 12

Question 36

which cells of the blastocyst secrete HCG?

Answer 36

syncytiotrophoblast

Question 37

what does the corpus luteum secrete?

Answer 37

progesterone

Question 38

when does bilaminar disc form?

Answer 38

day 8 which is the beginning of week 2 (BI-laminar - week 2) remember that week 2 is NOT day 14!! It's a 7 day period from day 8

Question 39

what cells form the primitive yolk sac

Answer 39

hypoblast

Question 40

how many cells in the blastocyst

Answer 40

100 - 200

Question 41

functions of the yolk sac

Answer 41

gas exchange blood cells nutrient delivery provides cells to the gut and germ cells etc.

Question 42

inside the cytotrophoblast, there is formation of extra-embryonic ****derm that forms which structures?

Answer 42

**** extra-embryonic mesoderm primitive stalk and chorionic cavity

Question 43

GFR peak at what gestational age

Answer 43

36 weeks?

Question 44

When does the foetus start to make HbA? what percentage of Hb is HbA at birth?

Answer 44

evidence the foetus can make HbA from 9-12 weeks however HbF is the predominate Hb HbA is around 10% of Hb at birth but predominate at 6 months postnatally

Question 45

When does the yolk sac start haematopoesis? When does the liver start haematopoesis?

Answer 45

day 17 (week 3) - yolk sac haematopoesis day 23 (week 4) - the first wave of haematopoietic cells colonize the liver.

Question 46

functional adult kidney develops from...

Answer 46

METAnephros

Question 47

epithelial lining of respiratory tubes is from which layer

Answer 47

endoderm (The smooth muscle, cartilage etc. is mesoderm)

Question 48

from what structure does the respiratory diverticulum bud? and what week?

Answer 48

foregut week 4

Question 49

what is the layer of mesoderm surrounding the respiratory diverticulum?

Answer 49

splanchnic mesochyme (splanchnic given that the respiratory diverticulum (endoderm) comes off the foregut) this makes the smooth muscle, connective tissue etc. of the respiratory tubes

Question 50

embryological origin of the visceral vs the parietal pleura (both are mesoderm, but what type?)

Answer 50

visceral pleura is splanchnic mesoderm parietal pleura is somatic mesoderm (next to chest wall)

Question 51

type 1 pneumocyte cell type and function

Answer 51

squamous cells very thin, for gas exchange N.B. the adjacent type 1 cells are connected by tight or occluding junctions that prevent leakage of fluid into the alveolar space.

Question 52

division day for: DCDA, MCDA, MCMA, conjoined twins

Answer 52

DCDA