Week 2 Development

Question 1

Where are the kidneys located in adults, and what is their blood supply?

Answer 1

Retroperitoneal, between T12-L3

Supply from renal artery branching of abdominal aorta

Question 2

What is the pronephron?

Answer 2

First kidney system- never functions in humans
BUT
important as has a duct which extends along length of embryo from cervical region to cloaca and drives development of next stage

Question 3

What is the mesonephros and its duct?

Answer 3

Mesonephric tubule develops causal to pronephros

Tubule + mesonephric duct= embryonic kidney

Question 4

What does the mesonephros do?

Answer 4

Sprouts uruteric bud which induces development of the metanephros
In males Mesonephric duct remains and is import in reproductive system

Question 5

What is the metanephros?

Answer 5

Functional kidney after birth

Ureteric bud induces development of the definitive kidney- releases mediators to create the metanephric blastema

Question 6

What mesoderm are the kidneys derived from?

Answer 6

Intermediate mesoderm

Question 6

How does the Ureteric duct induce the development of the adult kidney?

Answer 6

The contact of the bud to the metanephric bastema (undifferentiated tissue) allows the bud to expand and branch creating the minor and major calyx and renal pelvis
- drives the development

Question 7

How do the kidneys change position in development?

Answer 7

Kidneys ascent from the pelvic region to lumbar region

• creates new blood supply as moves up which pulls kidneys up
• cross the arterial fork formed by umbilical artery returning blood from fetus to placenta

Question 8

Congenital abnormalities- what is horseshoe kidney and how does it occur?

Answer 8

Kidneys fuse together in development and get stuck whilst ascending at inferior mesenteric artery

Question 9

Congenital abnormalities- what is renal agenesis?

Answer 9

When Ureteric bud fails to interact with intermediate mesoderm resulting in one kidney not developing

Question 10

Congenital abnormalities- How do duplication defects and ectopic Ureteric orifices occur?

Answer 10

Duplication either due to splitting of Ureteric bud- more buds= induction of more kidneys= additional lobe in affected kidney or ectopic Ureteric opening (into vagina)

Question 11

Congenital abnormalities- what is exstrophy of the bladder?

Answer 11

Bladder opens only abdominal wall

Question 12

In early development where do the GI, urinary and repro tracts all end?

Answer 12

Cloaca

Question 13

What is the urogenital sinus and how does it develop?

Answer 13

Created from hind gut by urogenital septum which grows downwards separating GI and urinary
Continuous with umbilicus by urachus- can remain patent in adults- median umbilical ligament

Question 14

In males how does the development continue through the sinus?

Answer 14

• Mesonephric duct reaches urogenital sinus
• Ureteric duct sprouts
• smooth musculature appears and urogenital sinus expands- consumes Ureteric bud allowing it to make its own separate opening into bladder
• Ureteric bud and mesonephric duct have independent openings to sinus
• androgens secreted support development of mesonephric duct into repro
• prostate and prostatic urethra formed

Question 15

In females how does the development continue?

Answer 15

• Mesonephric duct reaches urogenital sinus
• Ureteric bud sprouts from duct
• urogenital sinus expands and mesonephric duct begins to regress
• duct regression continues as no androgens and Ureteric bud opens into sinus

Question 16

What is the female urethra formed by?

Answer 16

Pelvic part of urogenital sinus

Question 17

What are the 4 parts of the male urethra?

Answer 17

Pre prostatic
Prostatic
Membranous
- pelvic part of urogenital sinus
Spongy- in penis
- Phallic part inductive influence of androgens

Question 18

What other possibly congenital abnormalities are there?

Answer 18

Migration of kidneys go wrong
Wilms tumour- congenital kidney tumour
Multicystic kidney disease- atresia of ureter= large fluid filled cysts