Lecture 2

Question 1

What cells give rise to urogenital system, which creates our kidneys and genitelia,

Answer 1

Intermediate mesoderm.

Question 2

What does the urogenital ridge consist of?

Answer 2

1. Gonadal ridge–> where testes and ovaries form
2. Nephrogenic cord–> makes nephron and duct collecting system

Question 3

What does the mesonephric tubule give rise to?

Answer 3

Nephron

Question 4

What are the three different kidneys that are produced during the production of the kidneys?

Answer 4

1st : Prenephros (non functional)

2nd: Mesonephros (functional)
3rd: Metanephros (true)

Question 5

How big are the kidneys in the emrbyo?

Answer 5

they run the length of the embryo

Question 6

1. Pronephros

A. When does it form and generate?

B. Where does it form?

C. What does it form?

Answer 6

A. Forms–> 4th week

• Degenerates –> late 4th week.

B. Forms in cervical region

C. Forms the pronephric duct (which, extends to the cloaca) and the pronephric tubule.

Question 7

2. Mesonephros

A. When does it form and when is it remodeled?

B. Where does it form?

C. What does it form?

Answer 7

A. Forms late 4th week and remains functional until the 11th week. Then, it is remodeled into genetilia for M and degenerates in F.

B. Cervical region

C.

• Pronephric duct–>mesonephric duct, which extends to the cloacha.
• Pronephric tubules degenerate and the mesonephric tubules form on the mesonephric duct, filtrating urine into the duct–> cloacha.

Question 8

3. Metanephros

A. When does it form and degenerate?

B. Where does it form?

C. What does it form?

Answer 8

A. Begins to develop in the 5th week and it remains functional forever.

B. Metanephros has 2 components that grow in the pelvis

• Uteric bud,
• Metanephrogenic blastema

Question 9

What are other names for the uteric bud?

Answer 9

1. Metanephric duct

2. Metanephric diverticulum

Question 10

What are other names for the metanephrogenic blastema?

Answer 10

1. Metanephrogenic mass

2, Metanephrogenic cap

Question 11

Nephrons are the functional unit of the kidney that consists of what?

Answer 11

1. Glomerular capillaries, which came from the dorsal arota
2. BC. which came from intermediate mesoderm
3. Mesonephric tubules, which came from intermediate mesoderm

Question 12

The nephron of mesonephros is the functional unit which consists of the glomeruli (from the dorsal aorta), bowmans capsule and mesonephric tubules which are from intermediate mesoderm.

The mesonephric duct does what?

Answer 12

1. Induces nephrons in the adjacent nephrogenic cord.
2. Mesonephric duct sends signals to the nephrogenic cord to form mesonephric vesicles.

A. Nephrogenic cord then send recipricol feedback to the duct.

–>B. Mesonephric vesicle elongatest to form a mesonephric tubule

–> C. Mesonephric tubule meets with the mesonephric duct

–> D. Mesonephric tubule continues to elongates and will will also surround the glomerulus, eventually forming the glomerular capsule.

—This creates and open system made up of: glomerular capsule + collecting system (mesonephric tubule) + mesonephric duct, allowing us to concentrate urine–> collect–> send to cloacha—-

Question 13

When the glomerular capsule is forms when…

Answer 13

The mesonephric tubule has fully merged with the mesonephric duct,

forming an open-system to concentrate urine, collect and send to cloacha.

Question 14

As we have said, the

metanephros = [uteric bud (metanephric duct) & metanephric blastema]

What are these two derived from?

Answer 14

Uretic bud (metanephric duct) and the metanephric blastema form in the pelvis.

Uteric bud–> grows from the mesonephric duct

Metanephric blastema–> derived from the nephrogenic cord

Question 15

In the development of the metanephros (true kidney),

how do the ureteric bud and metanephric blastema interact?

Answer 15

Uretic bud will grow towards the metanephric blastema, forming the tubules of the kidney.

-formation of the tubules is controlled via recipricol feedback.

Question 16

The ureteric bud gives rise to what from intermediate mesoderm? (5)

Answer 16

1. ureter
2. pelvis
3. major calyces
4. minor calyces
5. collecting tubules

Question 17

The metanephric blastema which is from the nephrogenic cord (intermediate mesoderm) forms what structures? (5)

Answer 17

1. Renal vesicles
2. bowman’s capsules
3. proximal/distal convoluted tubules
4. loop of henle

Question 18

How do we develop the collecting system of the kidney?

Answer 18

1. Uteric bud contacts metanephric blastema, creating the renal pelvis.
2. Uteric bifurcates and the branches coalesce to form major calyces.
3. 2nd generation of branching and coalesce occur again to form minor calyces.
4. Branching and coalescing continue, to make the collecting ducts.

Question 19

Now that the collecting ducts of the metanephros are made,

we need to make the nephrons. What do they originate as?

Answer 19

Nephrons orginate as a nephric vesicle, located wiithin the blastemic cap that surrounds the ampulla of the collecting duct.

Question 20

How are the nephrons of the metanephros made?

Answer 20

1. Collecting ducts will send signals to the metnephrogenic blastema to induce the formation of the nephric vesicle.
2. NV elongates and then surrounds around the glomerulus, forming the bowmans capsule.
3. Proximal end connect to the collecting duct forms the

• Proximal convulted tubule
• LoH
• Distal convoluted tubule

Question 21

Unilateral renal agenesis

• Males more affected, and many times more the
• Left kidney gone.
• Other kidney hypertrophies and takes on the role for both. Thus, no sx.
• What is looked for during an ultrasound at week 20?

Answer 21

when there is only one umbilical artery

Question 22

Bilateral renal agenesis

No kidney structures.

This could be mainly due to?

Answer 22

Oligohydramnios- lesser amnoitic fluid, causes lung hypoplasia.

20% of these cases are related to the Potter sequence (many other problems)

Question 23

What is the embryological mechanism is associated with bilateral renal agenesis?

Answer 23

The metanephros —

Ureteric bud didnt develop or it didnt get recipricol signal from blastema and then regressed

Question 24

What a duplex kidney and what is the embryological mechanism?

Answer 24

Duplex kidney is a double kidney with 2 ureters,

resulting from the abnormal division of the ureteric bud.

Question 25

While the metanephros is forming, the mesonephros is still there. During the **9th** week of fertilization what occurs?

Answer 25

1. The metanephros **accend** into the adult position due to caudal growth of the embryo. 2. As they are ascending, they **rotate 90 degree**s; causing the hilum to move from anterior--\> towards aorta.

Question 26

What is the blood supply to the metanephros kidneys?

Answer 26

**They get BS from whatever vessel is closest to them as they are ascending. Thus, the BV will continue to remodel until we form the renal vessels.** EX: pelvic area: common iliac aorta, once ascended

Question 27

Pelvic kidneys are ectopic kidney (not located in the right spot). Why do pelvic kidneys occur? (one kidney is ascended correctly and the other is not)

Answer 27

**the kidney does not ascend due to the cardinal vessels preventing it from ascending**

Question 28

A **horseshoe kidney** is when the inferior poles of the kidneys fuse together, and when they try to ascend, they do not. Why holds the kidneys from acending?

Answer 28

**The inferior mesenteric artery (IMA) off of the aorta to L3, which stops the kidney from migrating to L2**

Question 29

Accesory renal vesels are vesels that come from aorta to the kidney (end arteries are the only vessel suppplying that certain tissue). ## Footnote **What is common problem associated with accessory renal vessels?**

Answer 29

They commonly cross over the **ureters** to connect to the aorta which can compress the ureters causing an obstruction

Question 30

**_Cystic kidney disease_** and an AR disease where there are multiple small cysts in both kidneys due to a mutation in **PKHD1**. ## Footnote **What does this lead to?**

Answer 30

**renal insufficiency** and 25% cases have **lung hypoplasia** which are both due to oligohydramnios

Question 31

**_Multicystic dysplastic kidney disease_** is due to cysts caused by dilations of the loop of henle, usually only affecting one kidney. ## Footnote **What occurs?**

Answer 31

So people are asymptomatic, there are fewer cyst present compared to the other cystic disease. Other kidney picks up the slack

Question 32

Where are the following derived from: 1. Ureter 2. Bladder 3. Trigone

Answer 32

1. **Ureter**- mesonephric and metanephric ducts 2. **Bladder**- hindgut endoderm 3. **Trigone**- mesoderm

Question 33

In the adult, where does the **_ureter_** come from?

Answer 33

**ONLY THE METANEPHRIC DUCT (UTERIC BUD)**

Question 34

How do we form the ureter and bladder?

Answer 34

1. Ureteric bud grows out of the mesonephric duct 2. Mesonephric duct is then incorporated into the posterior bladder wall. 3. Ureteric bud becomes the adult ureter and inserts to the top of the posterior bladder wall. 4. Rest of the bladder is made from hindgut endoderm, except the trigone.

Question 35

All of the bladder is made up of hindgut endoderm except for which region?

Answer 35

Trigone (incorportation of mesonephric duct into the bladder wall) is made up of mesoderm

Question 36

The bladder is from hindgut endoderm. The cloacal membrane is made of _endo/ectoderm_ and will rupture. The cloacal membrane needs to be separated into? (2)

Answer 36

the _urogential membrane_ and _anal membrane_ via the _urorectal septum_

Question 37

The _urorectal septum (MESODERM)_ does what when it migrates?

Answer 37

it separates the [**urogenital system (above urorectal septum])** from the **rectum** (below), forming the *urogential membrane* and *anal membrane*- both are endo/ectoderm

Question 38

The **allantois** is an extension of hindgut endoderm from the bladder --\> goes into *umbilical cord*--\> becomes ***urachus*** which in the adult does?

Answer 38

it flattens out --\> becomes the **medial umbilical ligament** (abdomen stuff) \*\*clinical problems\*\*

Question 39

The ***urogenital sinus*** (bladder= hindgut endoderm) consists of 3 different regions, including?

Answer 39

1. **vesicle part** 2. **pelvis part** 3. **phallic part**

Question 40

Vesicle part--\> bladder Pelvis part--\> urethra in females and prosatic and membrabous urethra in M Phallic part--\> ?

Answer 40

**lining of the vaginal vestibule** in females **spongy urethra** in males

Question 41

When the allantois does not flatten out to form the median umbilical ligament, a urachal fistula can form. What happens?

Answer 41

abnormal connection to the belly button, allowing urine to leak out of the belly button during urination

Question 42

A **urachal cyst** is when a portion of urachus is maintained and forms a cyst... how is it found?

Answer 42

usually causes no problems, found during autopsy

Question 43

A **urachal sinus** is when there is a deep belly button, with some pathology in men can cause?

Answer 43

pressure in bladder which can open it up and create a urachal fistula

Question 44

**Exstrophy of the bladder (ectopic vesicae)** is when the bladder is on the outside of the anterior abdominal wall. What would cause this to occur?

Answer 44

during week 4, bc mesoderm did not insert between endo and ectoderm, causding the anterior abdominal wallto not close For bladder to close, we need a signal from that the abdominal wall did not close. so bladder is open as well

Question 45

**Epispadias** is improper location of genital tubercles caudal to cloacal membrane. Where would this opening be?

Answer 45

opening is on the dorsal side of the penis (remember erect penis is antatomical view) so top of penis when flaccid is gone \*\*commonly seen with ectopic vesicae

Question 46

**Suprarenal glands** have three different parts including the **medulla, capsule and cortex**. The cortex is derived from?

Answer 46

coelomic epithelium (somatic mesoderm layer of lateral plate)

Question 47

How is the cortex formed?

Answer 47

CELLULAR WAVE: coelomic epithelium forms a fetal cortex during week 6

Question 48

The medulla is formed from nueral crest cells which migrate to?

Answer 48

the fetal cortex chromaffin system/cells which give rise to medulla

Question 49

There is then a second wave of ceolomic epithelium in the cortex which forms the ?

Answer 49

adult/definitive cortex

Question 50

The capsule surrounding the kidneyy comes from?

Answer 50

mesonephric mesoderm (intermediate mesoderm)

Question 51

The fetal cortex is a source of a variety of hormones including _____ (2) and dihydroepiandrosterone (estrogen precursor) which is needed for placental development and pregnancy

Answer 51

pituitary ACTH and glucocorticoids