Hy Embryology 08 Part 2

Front 1

Describe the development of the urinary bladder

Back 1

1. Formed from the upper portion of the urogenital sinus, which is continuous with the allantois

2. The allantois becomes a fibrous cord called the urachus (or median umbilical ligament in the adult)

3. The lower ends of the mesonepric ducts become incorporated into the posterior wall of the bladder to form the trigone of the bladder

Front 2

Describe what happens to the allantois in development

Back 2

Becomes a fibrous cord called the urachus (or median umbilical ligament in the adult)

Front 3

Describe the formation of the trigone of the bladder

Back 3

The lower ends of the mesonephric ducts become incorportated into the posterior wall of the bladder to form the trigone of the bladder

Front 4

Describe renal agenesis

Back 4

1. Occurs when the ureteric bud fails to develop, thereby eliminating the induction of metanephric vesicles and nephron formation

2. Can be unilateral or bilateral

Front 5

Describe unilateral renal agenesis

Back 5

1. Relatively common (more common in males)

2. It is asymmetric and compatible with life because the remaining kidney hypertrophies

Front 6

Describe bilateral renal agenesis

Back 6

1. Relatively uncommon

2. It causes oligohydraminios, which causes compression of the fetus, resulting in Potter syndrome (deformed limbs, wrinkly skin, and abnormal facial appearance)

3. These infants are usually stillborn or die shortly after birth

Front 7

Describe renal ectopia

Back 7

1. Occurs when one or both kidneys fail to ascend and therefor remain in the pelvis or lower lumbar area (ie, pelvic kidney)

2. In some cases, two pelvic kidneys fuse to form a solid mass, commonly called a pancake kidney

Front 8

Describe renal fusion

Back 8

1. The most common type of renal fusion is the horseshoe kidney

2. A horseshoe kidney occurs when the interior poles of the kidneys fuse across the midline

3. Normal ascend of the kidneys is arrested because the fused portion gets trapped behind the interior mesenteric artery

4. Kidney rotation is also arrested so that the hilum faces ventrally

5. A horseshoe kidney may also cause urinary tract obstruction due to impingement on the ureters, which may lead to recurrent URIs as well as pyelonephritis

Front 9

Why is ascend of the kidneys arrested with horseshoe kidneys?

Back 9

The fused portion gets trapped behind the inferior mesenteric artery

Front 10

Describe the urinary complications associated with horseshoe kidney

Back 10

1. Can cause urinary tract obstruction due to impingement on the ureters

2. This can lead to recurrent UTIs and pyelonephritis

Front 11

Describe renal artery stenosis

Back 11

1. The most common cause of renvascular hypertension in children

2. The stenosis may occur in the main renal artery of segmental renal arteries

Front 12

Describe ureteropelvic junction obstruction (UPJ)

Back 12

1. Occurs when there is an obstruction to the urine flow from the renal pelvis to the proximal ureter

2. UPJ is the most common congenital obstruction of the urinary tract

3. If there is severe uteropelvic atresia, a multicystic dysplasia kidney is found, in which the cysts are actually dilated calcyes. In this case the kidney consists of grape-like, smooth-walled cysts of variable size. Between the cysts are found dysplastic glomeruli and atrophic tubules

Front 13

What is the most common congenital obstruction of the urinary tract?

Back 13

Ureteropelvic junction obstruction

Front 14

Describe autosomal recessive polycystic kidney disease

Back 14

1. Formally called infantile polycystic kidney disease

2. Autosomal recessive disease that has been mapped to the short art of chromosome 6

3. The kidneys (always bilateral) are huge and spongy with a smooth external surface and contain numerous cysts due to the dilatation of collecitng ducts and tubules thatseverely compromise kidney function

4. Associated clinically with cysts of the liver, pancreas, and lungs and hepatic fibrosis (hepatic hypertension)

5. Treatment includes dialysis and kidney transplant

Front 15

What is autosomal recessive polycystic kidney disease associated with clinically?

Back 15

Associated clinically with cysts of the liver, pancreas, and lungs and hepatic fibrosis (hepatic hypertension)

Front 16

What is the treatment for autosomal recessive polycystic kidney disease?

Back 16

Dialysis and kidney transplant

Front 17

Describe Wilms Tumor

Back 17

1. The most common renal malignancy of childhood

2. The most common primary tumor of childhood and is typically due to deletion of tumor suppressor gene WT1 located on chromosome 11

3. Presents as a large, solitary, well-circumscribes mass that on cut section is soft, homogeneous, and tan-gray in color

3. This tumor tends to recapitulate different stages of embryological formation of the kidney, so that three classic histological area are described:
i. A stromal area
ii. A blastemal area of tightly packed embryonic cells
iii. A tubular area

4. Associated with other congenital anaomalies in the WAGR complex [Wilms tumor, aniridia (absence of the iris), genitouirniary malformations, and metnal retardation]

Front 18

What is the most common renal malignancy in childhood?

Back 18

Wilms tumor

Front 19

What is the most common primary tumor of childhood?

Back 19

Wilms tumor

Front 20

Describe ureteropelvic duplications

Back 20

1. Occurs when the ureteric bud prematurely divides before penetrating the metanephric blastema

2. This results in either a double kidney or a duplicated ureter and renal pelvis

3. The term duplex kidney refers to a configuration where two ureters drain one kidney

4. The ureter from the lower pole opens normally at the urinary bladder trigone

5. The ureter from the upper pole usually has an ectopic opening

Front 21

Describe urachal fistulas or cysts

Back 21

1. Occurs when a remnant of the allantois persists, thereby forming a fistula or cyst

2. It is found along the midline on a path from the umbilicus to the apex of the urinary bladder

3. A urachal fistula forms a direct connection between the urinary bladder and the outside of the body at the umbilicus causing urine drainage from the umbilicus