Urinary System development

Question 1

What is the function of the pronephros in mammals?

Answer 1

-non-functional and the pronephros tubules are solid cords, but it is required in order for the rest of the excretorye system to develop

Question 2

In what organisms is the pronephros functional?

Answer 2

-fish and amphibians

Question 3

Describe the development structure of the pronephros.

Answer 3

• each pronephros consists of 7 nephrons
• each nephron develops from a single somite, from a region of the somite called the nephrotome
• these amniote pronephric tubules are solid
• laterally they are connected to a longitudinal duct called the pronephric duct

Question 4

What is the pronephric duct?

Answer 4

• duct extends from the pronephric tubules through the mesonephric ridge caudally to the cloaca
• two pronephric ducts, one on each side
• the pronephric duct will be renamed the mesonephric duct

Question 5

What induces the pronephric ducts?

Answer 5

RA -> Hox 4-11 genes -> Pax-2 and Pax-8 -Lim-1-> aggregation of mesenchymal cells in intermediate mesoderm into pronephric ducts

Question 6

In lower vertebrate embryos the proximal ends of the pronephric tubules open into the __________ cavity.

Answer 6

Coelomic

Question 7

What is the highly vascularized ridge that runs along the mesonephric ridge called?

Answer 7

-glomus

Question 8

What does the globus do?

Answer 8

• small molecules from the blood are filtered from the capillaries into the glomus into the Coelomic cavity
• from the coelom these materials move into the openings (nephrostomes) of the pronephric tubules and from there to the pronephric duct to the cloaca

Question 9

Where does the mesonephros develop? Is it a functional kidney?

Answer 9

• caudal to the pronephros
• functional kidney in most vertebrate embryos, including humans
• in salamanders the cranial part of the mesonephros does not function in the adult kidney -> functional is referred to as opisthonephros

Question 10

Describe the structure of the mesonephros.

Answer 10

• consists of mesonephric tubules that are longer than pronephric tubules and are often sigmoid or convoluted
• about 70 pairs of mesonephric tubules
• do not open into the coelom -> enclosed within expanded, double walled saclike invaginations of the proximal ends of then tubules

Question 11

Describe the structure of the nephrons in the mesonephros.

Answer 11

• cup like pockets called renal corpuscles
• enclosed capillary aggregations called glomeruli
• the mesonephric glomeruli are enclosed within the renal corpuscles, the vascular filtrate bypasses the coelom and goes directly into the nephron

Question 12

What do the distal. Ends. Of. The mesonephric tubules form?

Answer 12

• do not form their own excretory ducts
• they connect with existing pronephric ducts
• pronephric ducts are then renamed the mesonephric ducts/Wolffian ducts

Question 13

After the mesonephric tubules begin to function, the pronephric tubules/cords _________.

Answer 13

Degenerate

Question 14

The development of the mesonephric tube is dependent on the presence of what?

Answer 14

-pronephric duct

Question 15

What regulates the transformation of the intermediate mesenchyme to epithelium?

Answer 15

WT-1

Question 16

Just before the mesonephros attaches to the cloaca what happens? Why is this significant?

Answer 16

• mesonephric duct develops an evaginations called the uterus bud
• uterus bud initiates a series of inductive interactions that will result in the formation of the final kidney -> metanephric kidney

Question 17

What structure gives rise to the adult ureter, renal pelvis, and collecting tubules?

Answer 17

-metanephric diverticulum

Question 18

What does the metanephric. Diverticula induce?

Answer 18

-formation of the metanephrogenic blastema

Question 19

What does the metanephrogenic blastema do?

Answer 19

• will form the renal tubules of the adult kidney
• have a reverse inductive effect on the ureteric diverticula
• neither can continue to develop in the absence of the other

Question 20

Review the development of the metanephros in screen shots.

Answer 20

:)

Question 21

How do the utereric buds branch?

Answer 21

-GDNF from metanephrogenic mesenchyme

-causes tips of ureteric buds to
+produce FGF-2 and leukemia inhibitory factor
+induce surrounding metanephrogenic mesenchyme to form epithelial precursors of renal tubules

Question 22

What is the first kidney to develop?

Answer 22

Pronephros At 22 days of gestation