Gray's Anatomy Review
- Pelvis and Perineum
Exam Questions Verified
and Provided with A+
Graded Answers |Latest
Updated 2026/2027
,1 A 4-month-old male infant is admitted to the pediatric clinic because he was passing
urine near the anus rather than from the tip of his penis. Physical examination reveals that
the patient has perineal hypospadias. Which of the following embryologic structures
failed to fuse properly? A. Labioscrotal folds B. Cloacal membrane C. Urogenital folds D.
Genital tubercle E. Urogenital membrane
1 A. Perineal hypospadias is due to a failure of fusion of labioscrotal folds so that the
external urethral orifice is between the unfused halves of the scrotum. The cloacal
membrane is formed from endoderm of the cloaca and ectoderm of the proctodeum and
forms the future anus. The urogenital folds normally fuse along the ventral side of the
penis to form the spongy urethra. Epispadias is a condition in which the urethra opens on
the dorsal surface of the penis resulting from the genital tubercle developing more
dorsally during development. The urogenital membrane is bounded by the urogenital
folds and ruptures to form the urogenital orifice. GAS 466-468, 512; N 366; McM 265
2 A 2-day-old infant girl is diagnosed with tracheoesophageal fistula. In addition, physical
examination reveals an imperforate anus. A magnetic resonance imaging (MRI)
examination reveals that the rectum, vagina, and colon are joined into a single channel.
Which of the following structures is directly involved in this malformation? A.
Labioscrotal folds B. Persistent cloaca C. Urogenital folds D. Genital tubercle E.
Urogenital membrane
2 B. Most anorectal anomalies result from abnormal development of the urorectal
septum, ultimately resulting in nondivision of the cloaca into urogenital and anorectal
parts. The common outlet of the intestinal, urinary, and reproductive tracts is specifically
associated with a persistent cloaca. The labioscrotal folds are involved in forming the
external
urethral orifice only. The urogenital folds normally fuse along the ventral side of the
penis to form the spongy urethra. Epispadias is an anomaly in the development of the
genital
tubercle and involves the urethral orifice. The urogenital membrane is bounded by
the urogenital folds and ruptures to form the urogenital orifice. GAS 322, 430, 460; N
366; McM 266
,3 A 6-year-old boy is admitted to the hospital because of a palpable mass located
external to the aponeurosis of the external oblique. Radiographic examination reveals
that the mass is an ectopic testis, classified as interstitial. Failure of normal development
of which of the following embryologic structures is responsible for ectopic testis? A.
Gubernaculum B. Processus vaginalis C. Genital tubercle D. Seminiferous cords
E. Labioscrotal swellings
3 A. The gubernaculum arises in the upper abdomen from the lower end of the gonadal
ridge and helps guide the testis in its descent through the abdominal wall and then
into the scrotum. Ectopic testes occur when a portion of the gubernaculum passes to
an
abnormal position or otherwise fails to descend or become fixed to the skin of the
scrotum. The processus vaginalis is a tube of peritoneum that follows the same oblique
course through the body wall as the testis, ventral to the gubernaculum. The distal part
of the processus is retained as the tunica vaginalis. If part of the remainder of the
processus remains patent, it can fill with fluid as a hydrocele of the testis or spermatic
cord. The
genital tubercle forms the primordial phallus and is associated with epispadias. The
seminiferous cords form the primordia of the seminiferous tubules. The labioscrotal
swellings approach each other and fuse to form the scrotum. GAS 293-302, 470; N 364;
McM 266
, 4 A 2-month-old male infant has epispadias and the bladder mucosa is exposed to the
outside. Which of the following is the most likely cause of this condition? A. Failure of
the primitive streak mesoderm to migrate around the cloacal membrane B. Failure of
urethral folds to fuse C. Insufficient androgen stimulation D. Klinefelter syndrome E.
Persistent
allantois
4 A. When the urinary bladder mucosa is open to the outside in the fetus or newborn, the
condition is referred to as extrophy of the bladder. The extrophy results from failure of
the primitive streak mesoderm to migrate around the cloacal membrane, and it occurs
often in combination with epispadias. Penile hypospadias is characterized by a failure of
fusion of the labioscrotal folds, with the external urethral orifice located between the
two
unfused halves of the scrotum. Androgens are responsible for development of the testes.
Klinefelter syndrome is a condition in which the male has 47,XXY chromosomes. A
persistent allantois is associated with a patent urachus and an allantoic cyst. GAS 463;
N 348; McM 266
5 A bifid ureter or paired unilateral ureters result from partial or complete division of
which of the following embryologic structures? A. Ureteric bud/metanephric diverticulum
B. Mesonephric duct C. Paramesonephric duct D. Metanephric mesoderm E. Pronephros
5 A. The ureteric bud, or metanephric diverticulum, is an outgrowth from the
mesonephric duct. It is the primordium of the ureter, renal pelvis, the calyces, and the
collecting
tubules. Incomplete division results in a divided kidney with a bifid ureter. Complete
division results in a double kidney with a bifid ureter, or separate ureters. GAS 379, 462;
N 314; McM 267
- Pelvis and Perineum
Exam Questions Verified
and Provided with A+
Graded Answers |Latest
Updated 2026/2027
,1 A 4-month-old male infant is admitted to the pediatric clinic because he was passing
urine near the anus rather than from the tip of his penis. Physical examination reveals that
the patient has perineal hypospadias. Which of the following embryologic structures
failed to fuse properly? A. Labioscrotal folds B. Cloacal membrane C. Urogenital folds D.
Genital tubercle E. Urogenital membrane
1 A. Perineal hypospadias is due to a failure of fusion of labioscrotal folds so that the
external urethral orifice is between the unfused halves of the scrotum. The cloacal
membrane is formed from endoderm of the cloaca and ectoderm of the proctodeum and
forms the future anus. The urogenital folds normally fuse along the ventral side of the
penis to form the spongy urethra. Epispadias is a condition in which the urethra opens on
the dorsal surface of the penis resulting from the genital tubercle developing more
dorsally during development. The urogenital membrane is bounded by the urogenital
folds and ruptures to form the urogenital orifice. GAS 466-468, 512; N 366; McM 265
2 A 2-day-old infant girl is diagnosed with tracheoesophageal fistula. In addition, physical
examination reveals an imperforate anus. A magnetic resonance imaging (MRI)
examination reveals that the rectum, vagina, and colon are joined into a single channel.
Which of the following structures is directly involved in this malformation? A.
Labioscrotal folds B. Persistent cloaca C. Urogenital folds D. Genital tubercle E.
Urogenital membrane
2 B. Most anorectal anomalies result from abnormal development of the urorectal
septum, ultimately resulting in nondivision of the cloaca into urogenital and anorectal
parts. The common outlet of the intestinal, urinary, and reproductive tracts is specifically
associated with a persistent cloaca. The labioscrotal folds are involved in forming the
external
urethral orifice only. The urogenital folds normally fuse along the ventral side of the
penis to form the spongy urethra. Epispadias is an anomaly in the development of the
genital
tubercle and involves the urethral orifice. The urogenital membrane is bounded by
the urogenital folds and ruptures to form the urogenital orifice. GAS 322, 430, 460; N
366; McM 266
,3 A 6-year-old boy is admitted to the hospital because of a palpable mass located
external to the aponeurosis of the external oblique. Radiographic examination reveals
that the mass is an ectopic testis, classified as interstitial. Failure of normal development
of which of the following embryologic structures is responsible for ectopic testis? A.
Gubernaculum B. Processus vaginalis C. Genital tubercle D. Seminiferous cords
E. Labioscrotal swellings
3 A. The gubernaculum arises in the upper abdomen from the lower end of the gonadal
ridge and helps guide the testis in its descent through the abdominal wall and then
into the scrotum. Ectopic testes occur when a portion of the gubernaculum passes to
an
abnormal position or otherwise fails to descend or become fixed to the skin of the
scrotum. The processus vaginalis is a tube of peritoneum that follows the same oblique
course through the body wall as the testis, ventral to the gubernaculum. The distal part
of the processus is retained as the tunica vaginalis. If part of the remainder of the
processus remains patent, it can fill with fluid as a hydrocele of the testis or spermatic
cord. The
genital tubercle forms the primordial phallus and is associated with epispadias. The
seminiferous cords form the primordia of the seminiferous tubules. The labioscrotal
swellings approach each other and fuse to form the scrotum. GAS 293-302, 470; N 364;
McM 266
, 4 A 2-month-old male infant has epispadias and the bladder mucosa is exposed to the
outside. Which of the following is the most likely cause of this condition? A. Failure of
the primitive streak mesoderm to migrate around the cloacal membrane B. Failure of
urethral folds to fuse C. Insufficient androgen stimulation D. Klinefelter syndrome E.
Persistent
allantois
4 A. When the urinary bladder mucosa is open to the outside in the fetus or newborn, the
condition is referred to as extrophy of the bladder. The extrophy results from failure of
the primitive streak mesoderm to migrate around the cloacal membrane, and it occurs
often in combination with epispadias. Penile hypospadias is characterized by a failure of
fusion of the labioscrotal folds, with the external urethral orifice located between the
two
unfused halves of the scrotum. Androgens are responsible for development of the testes.
Klinefelter syndrome is a condition in which the male has 47,XXY chromosomes. A
persistent allantois is associated with a patent urachus and an allantoic cyst. GAS 463;
N 348; McM 266
5 A bifid ureter or paired unilateral ureters result from partial or complete division of
which of the following embryologic structures? A. Ureteric bud/metanephric diverticulum
B. Mesonephric duct C. Paramesonephric duct D. Metanephric mesoderm E. Pronephros
5 A. The ureteric bud, or metanephric diverticulum, is an outgrowth from the
mesonephric duct. It is the primordium of the ureter, renal pelvis, the calyces, and the
collecting
tubules. Incomplete division results in a divided kidney with a bifid ureter. Complete
division results in a double kidney with a bifid ureter, or separate ureters. GAS 379, 462;
N 314; McM 267
