Embryology

Question 1

what layer of the embryo forms the kidneys?

Answer 1

the mesoderm

Question 2

which part of the mesoderm are the kidneys derived from?

Answer 2

intermediate mesoderm

Question 3

what are nephrotomes?

Answer 3

segments of the intermediate mesoderm

aka nephric structures

Question 4

in which direction does development of the nephric structures occur?

Answer 4

craniocaudal

Question 5

name the three nephric structures formed in the order they appear

Answer 5

pronephros
mesonephros
metanephros

Question 6

what is another name for the pronephros?

Answer 6

the pronephric system

Question 7

where does the pronephros form?

Answer 7

the cervical region of the embryo

Question 8

when does the pronephros undergo segmentation?

Answer 8

the beginning of week four

Question 9

when does the pronephros regress?

Answer 9

completely gone by the end of week 4

Question 10

what is another name for the mesonephros?

Answer 10

the mesonephric system

Question 11

where does the mesonephros form?

Answer 11

the thoracic and lumbar regions

Question 12

what does the mesonephros form?

Answer 12

mesonephric tubules

these act as temporary excretory units

Question 13

what are the mesonephric tubules in contact with?

Answer 13

vasculature at one end

mesonephric duct at the other

Question 14

what is the mesonephric duct?

Answer 14

a longitudinal duct running alongside the intermediate mesoderm, connecting to the developing bladder

Question 15

what is another name for the metanephros?

Answer 15

the metanephric system

Question 16

where does the metanephros develop?

Answer 16

the sacral region of the embryo

Question 17

how many mesonephric tubules are formed?

Answer 17

40

appear in a craniocaudal fashion

Question 18

what happens to the mesonephric tubules at week 5?

Answer 18

the cranial ones regress, leaving some lumbar ones

Question 19

when do the mesonephric tubules function?

Answer 19

weeks 6-10

then they regress

Question 20

when does the metanephros appear?

Answer 20

week 5

Question 21

what does the metanephros form?

Answer 21

the kidney proper

Question 22

when does the metanephros begin to function?

Answer 22

between weeks 9-11

Question 23

what two distinct structures form from the metanephros?

Answer 23

ureteric bud

metanephric blastema

Question 24

what is the metanephric blastema?

Answer 24

a mass of intermediate mesoderm

Question 25

what is the ureteric bud?

Answer 25

a outgrowth from the mesonephric duct

Question 26

what do the metanephric blastema and the ureteric bud form?

Answer 26

the kidney proper

Question 27

when does the ureteric bud develop?

Answer 27

around day 28

Question 28

when do the ureteric bud and the metanephric blastema fuse?

Answer 28

day 32

Question 29

how do the ureteric bud and metanephric blastema develop after fusio?

Answer 29

through reciprocal induction both send signals to help the other develop

Question 30

what happens if the ureteric bud and metanephric blastema fail to communicate?

Answer 30

agenesis

Question 31

what are the two possible mechanisms leading to agenesis in development?

Answer 31

the ureteric bud is not long enough the ureteric bud fails to develop

Question 32

what does the ureteric bud form?

Answer 32

the collecting system of the kidneys

Question 33

how does the ureteric bud form the collecting system?

Answer 33

two cycles of branching and intussusception, followed by a final branching cycle

Question 34

describe the appearance of the embryonic kidney

Answer 34

very lobulated and lumpy

Question 35

what does the metanephric blastema form?

Answer 35

the nephrons

Question 36

what are the four parts of a nephron?

Answer 36

bowman's capsule proximal convoluted tubule loop of henle distal convoluted tubule

Question 37

what part of the nephron interacts with the vasculature?

Answer 37

bowman's capsule

Question 38

what is the loop of henle divided into?

Answer 38

ascending and descending limbs

Question 39

when do the kidneys ascend from the pelvis?

Answer 39

weeks 6-9

Question 40

what is the initial blood supply to the kidneys in the pelvis?

Answer 40

common iliac arteries

Question 41

what is it called when one kidney fails to ascend?

Answer 41

pelvic kidney

Question 42

what is it called when the inferior poles of the kidney fuse?

Answer 42

horseshoe kidney

Question 43

what issue do horseshoe kidneys run into?

Answer 43

cannot ascend, they get trapped under the IMA

Question 44

what is the cloaca?

Answer 44

an expansion of hindgut endoderm

Question 45

what are the two divisions of the cloaca?

Answer 45

rectum | primitive urogenital sinus

Question 46

what divides the cloaca?

Answer 46

urorectal septum

Question 47

what does the primitive urogenital sinus give rise to?

Answer 47

bladder pelvic urethra definitive urogenital sinus

Question 48

how is the bladder in contact with the umbilical cord?

Answer 48

via the allantois

Question 49

what is the remnant of the allantois called?

Answer 49

the urachus