Week 2.1 - Development of the urinary system (workbook, embryology)

Question 1

where does the kidney and ureter develop from?

Answer 1

both from intermediate mesoderm at the urogenital ridge

Question 2

what is the sequence of events?

Answer 2

pronephros
mesonephros
metanephros

Question 3

what is the function of the mesonephric duct?

Answer 3

very important role in the development of the duct system of the male reproductive tract

Question 4

what does the mesonephric duct sprout?

Answer 4

the ureteric bud - the primoridum of the collecting system of the definitive kidney

Question 5

when does the mesonephros appear and regress?

Answer 5

appear week 4, regress week 8

Question 6

where does the excretory system develop from?

Answer 6

metanephric tissue cap

Question 7

what is the narrowed lower segment of urogenital sinus’ derivative in male urethra?

Answer 7

pre-prostatic urethra, prostatic & urethra membranous urethra

Question 8

what does the phallic portion (enclosed by urethral folds) become in male urethra?

Answer 8

spongy urethra

Question 9

where does the kidney shift in position during its development?

Answer 9

from the pelvis to the abdomen

Question 10

why do the kidneys shift from the pelvis to the abdomen?

Answer 10

because of migration and expansion of the caudal (tail) region of the foetus

Question 11

what does migration of the caudal region of the foetus include?

Answer 11

1. craino-caudal shift from L4-L1/T12
2. lateral displacement (meeting up with the adrenal glands in the process)
3. a 90 degrees rotation so the renal pelvis faces the midline

Question 12

what is the bladder a derivative of?

Answer 12

the hindgut

Question 13

what does it mean when the bladder is a derivative of the hindgut?

Answer 13

it is derived from the caudal portion of the primitive gut tube formed during embryonic folding in the fourth week of development

Question 14

what does the caudal portion contain?

Answer 14

a dilated blind pouch called the cloaca

Question 15

what is the cloaca separated from the outside by?

Answer 15

cloacal membrane - one of the 2 mesoderm (less regions present after gastrulation)

Question 16

what is also involved in the development of the bladder?

Answer 16

the allantois

Question 17

what is the allantois?

Answer 17

a superoventral diverticulum of the hundgut and extends into the umbilical cord

Question 18

what does the lumen of the allantois become?

Answer 18

obliterated to become the urachus, which is the median umbilical ligament in adults

Question 19

what happens to the cloaca?

Answer 19

becomes divided by the urorectal septum into the urogenital sinus and anorectal canal

Question 20

what does the urogenital sinus and anorectal canal?

Answer 20

US: future bladder and urethra
AC: future rectum and anal canal

Question 21

what is the urethra formed by?

Answer 21

narrowing of the lower urogenital sinus

Question 22

how does the distal portion differ in development?

Answer 22

differs between male and female

Question 23

when does the distal portion of the urethra develop?

Answer 23

as the external genitalia change from an indifferent starting point to the morphology dictated by the genotype of the embryo

Question 24

in males, how is the distal urethra like?

Answer 24

elongated (become the spongy urethra)

Question 25

how does the penis develop?

Answer 25

fusion of the urethral folds under the influence of male sex hormones

Question 26

in females, what does the urethra open into?

Answer 26

the vestibule

Question 27

why does the urethra open into the vestibule in females?

Answer 27

because the urethral folds do not fuse

Question 28

how is the male urethra split?

Answer 28

into 4 parts:
pre-prostatic urethra
prostatic
membranous
spongy