Development of the Urinary System

Question 1

Also referred to as nephrogenic plate

Answer 1

intermediate mesoderm

Question 2

Early proliferation of this portion of the mesoderm causes a longitudinal swelling– termed the ____

Answer 2

urogenital plate

Question 3

urogenital plate consists of

Answer 3

nephrogenic cord

gonadal ridge

Question 4

Laterally-positioned ____ (which forms kidneys & ureter)

Answer 4

nephrogenic cord

Question 5

Medially-positioned ____ (for ovary/testis & female/male genital tract formation).

Answer 5

gonadal ridge

Question 6

THREE GENERATIONS OF KIDNEY PRIMORDIA

Answer 6

• Pronephros
• Mesonephros
• Metanephros

Question 7

• Consists of seven or eight pairs of pronephric tubules that appear briefly at the level of somites seven to 14.
• In the sheep, pronephric tubules become quite well developed and connect to the pronephric duct.
• The tubules soon degenerate, but the pronephric duct persists as the mesonephric duct.

Answer 7

Pronephros

Question 8

• In domestic animals, 70–80 pairs of mesonephric tubules appear approximately between the levels of somites nine through 26.
• The functional kidney for fish and amphibians.
• Largest in species with a six-layered placental barrier such as the pig and sheep, and smallest in carnivores with a four-layered barrier

Answer 8

Mesonephros

Question 9

• The mesonephric tubules lengthen rapidly, form an S-shaped loop, and acquire a tuft of capillaries that later form the ____ at their medial extremity..
• Around each glomerulus, the tubulus forms a ____
• Together these structures constitute a ____

Answer 9

glomerulus

Bowman’s capsule

renal corpuscle

Question 10

The third generation of urinary organs that matures to form the permanent kidney of reptiles, birds, & mammals.

Answer 10

Metanephros

Question 11

metanephros Originates from two sources:

Answer 11

• Ureteric bud
• Metanephric blastema

Question 12

• Grows out of the mesonephric duct in the region of the cloaca
• Eventually develops into the ureter, renal pelvis, and numerous collecting ducts

Answer 12

URETERIC BUD

Question 13

• Metanephrogenic mass
• The caudal region of the nephrogenic cord.

Answer 13

METANEPHRIC BLASTEMA

Question 14

*Nephron Formation

Mesodermal cells proliferate to form ____.

The cords canalize and elongate, becoming S-shaped ____ and eventually nephrons

One end of each metanephric tubule establishes communication with a collecting tubule; the other end of the
tubule expands to surround a capillary ____.

Between the two ends, each metanephric tubule differentiates into the regions characteristic of a nephron (_____)

Answer 14

cell cords

metanephric tubules

glomerulus

proximal segment, thin loop, & distal segment

Question 15

*Species differences

• The kidney develops 12– 25 separate lobes, each retaining its distinct pyramid forming papillae, therefore often referred to as a multipyramidal kidney.
• With distinct gross lobulationas
• No renal pelvis

Answer 15

Cattle

Question 16

• The cortex is not lobated but the medulla is subdivided into renal pyramids forming papillae and so multipyramidal.
• No distinct gross lobulations

Answer 16

Pig, Man

Question 17

The cortex undergoes a complete fusion resulting in a nonlobated, smooth surface of the kidney.

• No calyces are formed
• Fusion of the apical regions of the medullary pyramids results in the formation of a ridge-like common papilla, the renal crest.

Answer 17

HORSE, SMALL RUMINANTS, AND CARNIVORES

Question 18

Develops from expansion of the cranial end of the urogenital sinus, including the adjacent portion of the urachus.

Answer 18

Urinary bladder

Question 19

The primitive urogenital sinus divides into the ____, the primordium of the bladder, and a ____.

Answer 19

cranial vesico‐urethral canal

caudal urogenital sinus proper

Question 20

The ____ in the dorsal wall of the bladder is lined by epithelium of mesodermal origin whereas the rest of the bladder epithelium is derived from the endoderm

Answer 20

trigone

Question 21

urethra Develops from the _____.

Answer 21

urogenital sinus

Question 22

*Gender specific

• In females, the mid region of the urogenital sinus becomes ____.
• The caudal region of the urogenital sinus become _____.
• The _____ arises as an outgrowth of the vestibule.

Answer 22

urethra

vestibule

vagina

Question 23

*Gender specific

In males, the _____ develops from the mid region of the urogenital sinus and the ____ develops from elongation of the caudal end of the urogenital sinus.

Answer 23

pelvic urethra

penile urethra

Question 24

Derived from neural crest (ectoderm).

Answer 24

ADRENAL MEDULLA

Question 25

Arises from cells of mesonephric nephrons
that dissociate from the nephron when the
mesonephros degenerates.

Answer 25

ADRENAL CORTEX

Question 26

• Condition in which one or both kidneys fail to develop
• Unilateral or bilateral

Answer 26

RENAL AGENESIS

Question 27

• An intermediate condition between a normal kidney and renal agenesis
• Hereditary condition in Cocker Spaniels, Norwegian Elkhounds, Samoyeds, Keeshonds, Bedlington Terriers

Answer 27

RENAL HYPOPLASIA

Question 28

Duplication of the renal pelvis to the production of a complete supernumerary organ.

Answer 28

RENAL DUPLICATIONS

Question 29

The metanephros gives rise to a kidney which remains in the sacral region.

Answer 29

ECTOPIC KIDNEY

Question 30

Abnormal renal structure formed by the fusion of the caudal poles of bilateral pelvic kidneys

Answer 30

HORSESHOE KIDNEY

Question 31

• Arises from the accumulation of urine within nephrons which fail to connect to their collecting duct system
• Autosomal dominant pattern in Persian cats

Answer 31

CONGENITAL CYSTIC KIDNEY

Question 32

• Entry of the ureters into the vagina or urethra instead of the bladder
• High risk exists in Siberian Huskies, West Highland Terriers and small Poodles

Answer 32

ECTOPIC URETER

Question 33

Results from a failure of the allantoic stalk to close at birth.

Answer 33

PATENT URACHUS (URACHAL FISTULA)