E - Development of The Urinary System

Question 1

Main functions (4) of the urinary system include:

Answer 1

Removal of metabolic waste products such as urea; maintain electrolyte, water and pH balance; regulation of blood pressure, blood volume and erythropoietin; vitamin D synthesis

Question 2

Development of the urniary system is tightly linked to…

Answer 2

Development of the reproductive system in early stages, until the urinary system eventually develops ahead

Question 3

The urinary system consists of…

Answer 3

The kidneys, ureters, bladder and urethra

Question 4

What tissue gives rise to the structures of the urinary system?

Answer 4

The urogenital ridge of the intermediate mesoderm

Question 5

The kidneys develop from…

Answer 5

The overlapping sequential systems - pronephros, mesonephros and metanephros.

Question 6

Pronephro development begins in…

Answer 6

The fourth week of gestation in the cervical region

Question 7

First stage of pronephro development

Answer 7

6-10 pairs of segmented tubules deriving from the intermediate mesoderm called nephrotomes are formed.

Question 8

Second stage of pronephros development

Answer 8

Nephrotomes join with a pronephric duct - a duct which extends from the cervical region to the cloaca - this system regressed by the end of week 4

Question 9

Cloaca

Answer 9

Distal end of the embryo

Question 10

The mesonephros develops

Answer 10

Caudally/inferiority to the pronephros

Question 11

First stage of mesonephros development

Answer 11

Presence of the pronephric duct stimulates the thoracolumbar region of the intermediate mesoderm to form mesonephric tubules

Question 12

Second stage of mesonephros development

Answer 12

Mesonephric tubules receive a tuft of capillaries from the dorsal aorta - empty into the mesonephric duct (continuation of the pronephric duct) which acts as the primitive blood filtration system for the growing embryo - most of these tubules regress by the second month

Question 13

The mesonephric duct…

Answer 13

Sprouts the ureteric bud caudally which induces development of the definitive kidney

Question 14

Metanephros development forms… and occurs…

Answer 14

The definitive kidney - occurs between the 5th and 12th weeks

Question 15

First stage of metanephros development

Answer 15

The ureteric bud from the mesonephric duct makes contact with the caudal region of intermediate mesoderm = forms the metanephric blastema which is the metanephric system

Question 16

Metanephric system has two components

Answer 16

Collecting system and excretory system

Question 17

The metanephric collecting system is derived from…

Answer 17

The ureteric bud

Question 18

The metanephric collecting component gives rise to..

Answer 18

The ureter, renal pelvis, major/minor calyces and collecting tubules. Terminates at the distal convoluted tubule.

Question 19

If the ureteric bud splits too early…

Answer 19

Can give rise to two ureters or two renal pelvices connected to one ureter

Question 20

The metanephric excretory component is derived from…

Answer 20

Metanephric blastema

Question 21

First stage of metanephric excretory component

Answer 21

Each collecting tubule from the collecting component is capped with a metanephric tissue cap - gives rise to excretory tubules

Question 22

Excretory tubules in the metanephric excretory component give rise to

Answer 22

The nephrons

Question 23

The proximal end of the metanephric excretory tubule forms

Answer 23

The bowman’s capsule around a glomerulus

Question 24

The distal end of the metanephric excretory tubule forms

Answer 24

The proximal convoluted tubule, loop of henle and distal convoluted tubule

Question 25

The definitive kidney develops…

Answer 25

In the pelvic region but eventually ascends into the abdomen

Question 26

In the pelvis, the kidney…

Answer 26

Receives its blood supply from a pelvic branch of the abdominal aorta

Question 27

As the kidney ascends during development…

Answer 27

It receives new arteries from the abdominal aorta

Question 28

The pelvic renal arteries…

Answer 28

Usually regress, but can continue as accessory renal arteries

Question 29

Horseshoe kidney/cake kidney/fused kidney

Answer 29

Where the two developing kidneys fuse into one horseshoe-shaped kidney

Question 30

Development of horseshoe kidney

Answer 30

Occurs when kidneys become to close in abdominal ascent - become fused and stuck underneath the inferior mesenteric artery

Question 31

Horseshoe kidneys are…

Answer 31

Still drained by two ureters and asymptomatic but prone to obstruction

Question 32

What are the bladder and urethra derived from?

Answer 32

The cloaca

Question 33

What happens to the cloaca in weeks 4-7 of urinary development

Answer 33

Divided into two parts by the uro-rectal sinus

Question 34

The anterior section of the uro-rectal septum

Answer 34

The urogenital sinus

Question 35

Upper section of urogenital sinus

Answer 35

Forms the bladder

Question 36

Pelvic section of uro-genital sinus

Answer 36

Forms The entire urethra and some of reproductive tract jn females. Forms membranous and prostatic urethra in males

Question 37

Phallic section of uro-genital sinus

Answer 37

Forms part of the female reproductive tract. Forms the spongy urethra in males

Question 38

Posterior section of uro-rectal septum

Answer 38

Anal canal

Question 39

What is the urinary bladder initially drained by during gestation?

Answer 39

The allantois

Question 40

What happens to the allantois?

Answer 40

Gets obliterated into the urachus (a fibrous chord). The remnant of the urachus can be seen as the median umbilical ligament within adults. (Connects apex of bladder to umbilicus)

Question 41

What happens to bladder as it develops from urogenital sinus

Answer 41

It absorbs the caudal parts of the mesonephric ducts (Woffian ducts) - forms the trigone of the bladder.

Question 42

Ureter/bladder connection

Answer 42

Ureters sprout from the mesonephric ducts and connect to the base of the trigone bladder

Question 43

What happens in both males and females as kidneys ascend in abdomen?

Answer 43

The ureteric openings move cranially

Question 44

What happens to mesonephric ducts in males and females?

Answer 44

(Males) Move caudally and closer together, enter prostatic urethra to become ejaculatory ducts. (Females) degenerate due to a lack of testicular androgens.

Question 45

What is the urethra formed by in males?

Answer 45

Prostatic and membranous urethra is formed by the pelvic uro-genital sinus. The spongy urethra is formed by the phallic uro-genital sinus

Question 46

What is the urethra formed by in females?

Answer 46

The pelvic part of the urogenital sinus