Embryology

Question 1

from what layer does the urogenital system develop speicifcally?

Answer 1

mesoderm layer - intermediate mesoderm

Question 2

In the lateral folding of embryo picture shown, label all the parts with arrows in order of top to bottom

Answer 2

• Neural tube
• Paraxial mesoderm –> somites
• Intermediate plate mesoderm –> UG system
• Endoderm
• Ectoderm
• Lateral plate mesoderm: somatic
• Lateral plate mesoderm: splanchnic
• Intra-embryonic coelom

Question 3

where does the intermediate mesoderm lie?

Answer 3

on the posterior abdominal wall

Question 4

• whereabouts is the amniotic cavity
• whereabouts is the yolk sac - what lines it?
• what does ectoderm form?

Answer 4

• amniotic cavity - layer outisde ectoderm
• yolk sac is lined by endoderm (sits inside endoderm)
• ectoderm forms skin coverings of whole of embryo, neural tube & notochord

Question 5

in this midsagittal section of the head and tail fold, what do the light blue and black lines represent?

Answer 5

• light blue= boundary of amniotic cavity
• black= chorion

Question 6

in this last picture in this diagram, the head and tail fold join to form the ………. that later goes on to form the ………..

Answer 6

body stalk that later goes on to form umbilical cord

Question 7

what is the Allantois and what is it connected to?

Answer 7

it is an outpouching of the endoderm at the hindgut that extends into the body stalk, and is connected to the cloaca

Question 8

What is the cloaca?

Answer 8

is a single posterior opening for a bird’s digestive, urinary and reproductive tracts & is used to expel faeces and lay eggs

Question 9

What happens to the cloaca in humans?

Answer 9

• divides into 2 different tubes:
• Urogenital sinus anteriorly
• Rectum posteriorly

Question 10

wht divides the UG sinus and rectum?

Answer 10

the urorectal septum

Question 11

what does the UG sinus go on to form?

Answer 11

urinary bladder and urethra

Question 12

after the development of the urinary bladder and urethra, from cloaca and allantois, what happens?

Answer 12

Intermediate mesoderm develops into the rudimentary pronephros in neck (week 4), Mesonephros in trunk region (week 5 to 9) with a duct and tubules

Question 13

where does the mesonephric duct drain into?

Answer 13

UG sinus

Question 14

• what is the 3rd set of kidneys called
• what region does it develop from
• what does it consist of?

Answer 14

• metanephros
• develops from pelvic region
• consists of ureteric bud & metanephric mesoderm

Question 15

where does ureteric bud grow out of?

Answer 15

caudal end of mesonephric duct

Question 16

what does ureteric bud develop into?

Answer 16

kidneys and ureters - branches to form ureters, renal pelvis, calyces and collecting tubules

Question 17

what does the mesonephric duct go on to form?

Answer 17

vas deferens

Question 18

in females, what does mesonephros become?

Answer 18

ovary

Question 19

how does the nephron develop overall?

Answer 19

the ureteric bud and metanephric mesoderm reciprocally induce one another

Question 20

what happens to the kidneys once they have developed, but are in pelvic area?

Answer 20

• they rise due to differential growth of abdominopelvic structures
• aquire new blood vessels & hilum rotates to face medially
• Stops when come in contact with adrenal glands