1.
The transitional epithelium lining the urinary bladder is derived from
Correct Answer
B. Endoderm
Explanation
The transitional epithelium lining the urinary bladder is derived from endoderm because
the urinary bladder develops from the upper end of the urogenital sinus. The origin of the urogenital
sinus can be traced back to the gut tube, which is lined by endoderm. •
2.
During surgery for a benign cyst on the kidney, the surgeon notes that the patient's right kidney has two ureters and two renal pelves. This malformation is
Correct Answer
E. A premature division of the ureteric bud
Explanation
The ureteric bud seems to be preprogrammed to undergo repeated divisions. These divisions
normally begin on contact with the metanephric blastema. If the ureteric bud undergoes division
prematurely, duplication of the ureter and renal pelvis occurs. In some circumstances, two sepa-
rate kidneys form.
3.
When does the metanephros become functional?
Correct Answer
C. At week 10 of development
Explanation
The metanephros begins to form at week 5 and starts to function in the fetus at about week
10. The pronephros is not functional in humans; it is the interim kidney, which functions until
the metanephros is ready.
4.
A urachal cyst is a remnant of the
Correct Answer
D. Allantois
Explanation
The upper end of the urogenital sinus is in patent communication with the allantois, which
lies in the umbilical cord. The allantois normally regresses and forms a fibrous cord. If a remnant
persists, it forms a urachal cyst or sinus.
5.
The transitional epithelium lining the ureter is derived from
Correct Answer
C. Mesoderm
Explanation
The transitional epithelium lining the ureter is derived from mesoderm because the ureter
develops from the ureteric bud. The ureteric bud is a diverticulum from the mesonephric duct
whose origin can be traced back to the intermediate mesoderm.
6.
The podocytes of Bowman's capsule are derived from
Correct Answer
C. Mesoderm
Explanation
The podocytes of Bowman's capsule develop from the metanephric vesicles, which are of
mesodermal origin.
7.
The proximal convoluted tubules of the definitive adult kidney are derived from the
Correct Answer
B. Metanephric vesicle
Explanation
The distal convoluted tubule, loop of Henle, proximal convoluted tubule, and Bowman's
capsule all are derived from the metanephric vesicle.
8.
The trigone on the posterior wall of the urinary bladder is formed by the
Correct Answer
A. Incorporation of the lower end of the mesonephric ducts
Explanation
The lower end of the mesonephric ducts is incorporated into the posterior wall of the urinary
bladder. The mesonephric ducts contribute to the connective tissue component of the posterior
wall at the trigone. It is generally believed that the transitional epithelium lining the entire
bladder (even the trigone) is of endodermal origin.
9.
A 6-year-old girl presents with a large abdominal mass just superior to the pubic symphysis. The mass is tender when palpated and fixed in location. During surgery, a fluid-filled mass is noted, which is connected to the umbilicus superiorly and to the urinary bladder inferiorly. What is the diagnosis?
Correct Answer
D. Urachal cyst
Explanation
A urachal cyst or sinus forms from a remnant of the allantois and is found along the mid-
line on a path from the umbilicus to the apex of the urinary bladder. The epithelium lining the
cyst produces secretions that gradually fill the remnant with fluid. Very rarely, the entire allan-
tois persists, forming a fistula that is patent from the urinary bladder to the exterior at the umbilicus.
10.
Immediately after birth of a boy, a moist, red protrusion of tissue is noted just superior to his pubic symphysis. After observation, urine drainage is noted from the upper lateral corners of this tissue mass. What is the diagnosis?
Correct Answer
E. Exstrophy of the bladder
Explanation
The moist, red tissue mass that is exposed to the exterior is actually the posterior wall of
the urinary bladder. This is called exstrophy of the bladder and is caused when the anterior
abdominal wall and anterior wall of the bladder fail to form. The ureters open onto the posterior
wall; therefore, urine drainage is apparent.