Development of the Genital System

Question 1

What is the coelomic epithelium?

What does it give rise to?

Answer 1

Outer somatic mesoderm that lines the urogenital ridge.

Primary sex cords.

Question 2

Where are the primordial germ cells found?

Answer 2

In the allantois/yolk sac endoderm.

Question 3

Primordial germ cells of men and women:

Answer 3

Men: Sertoli cells and Leydig cells.
Women: follicle cells and thecal cells.

Question 4

Migration of gametes and timeline

Answer 4

Arise from the epiblast in wk 2 and migrate through the primitive streak in wk 3 to reside in the yolk sac and allantois.
MIgrate back via dorsal mesentary in wk 5.
Colonize the primary sex cords in wk 6.

Question 5

Amount of oogonia in:
5th prenatal month
Birth
Puberty
Released

Answer 5

5th prenatal month: 6 million
Birth: 1 million
Puberty: 40K
Released: 400

Question 6

Central event of sex determination:

Secondary events of sex determination:

Answer 6

Central event is the differentiation of the testes.

Secondary events are the production of humoral factors by gonads.

Question 7

SRY gene

Answer 7

Upregulates testis-specific genes

Question 8

XY mice w/o SRY

XX mice w/ SRY

Answer 8

Will demonstrate the opposite sex’s characteristics but are sterile. Not hermaphrodites.

Question 9

Draw the pathway of sex determination in men

Answer 9

Notes

Question 10

Draw the pathway of sex determination in women

Answer 10

Notes

Question 11

What happens when the is no AMH in males?

Answer 11

Male and female internal genitalia w/ male external genitalia.

Question 12

What happens in a 5a-reductase deficiency (no DHT) in males?

Answer 12

Male internal genitalia w/ ambiguous/female external genitalia.

Question 13

When does gonadal development occur?

Answer 13

Wk 5

Question 14

Primary sex cords (medulla) does what in males and females?

Answer 14

Persists in males

Degenerates in females

Question 15

What do the primary sex cords become in males?

Answer 15

Seminiferous tubules and Sertoli cells

Question 16

Connective tissue in the males becomes?

Answer 16

Leydig cells and tunica albuginea

Question 17

Secondary sex cords (cortical cords) becomes what in females?

Answer 17

Primordial follicles and granulosa cells

Question 18

Thecal cells are from:

Answer 18

Intermediate mesoderm

Question 19

What happens to the mesonephric ducts in males and females?

Answer 19

Stays in males.

Degenerates in females to form epoophoron and paraophoron.

Question 20

What happens to the paramesonephric ducts in males and females?

Answer 20

Degenerates in males and persists in females.

Question 21

Mesonephric duct in males becomes (4)

Answer 21

Epididymis
Vas deferens
Seminal vesicle
Ejaculatory duct

Question 22

Mesonephric tubules in males becomes (2)

Answer 22

Efferent ducts

Rete testis

Question 23

How do the paramesonephric ducts create the uterine tubes and uterovaginal primordium?

Answer 23

Cranially, they remain separated to form the uterine tubes, and caudally they fuse to form the uterovaginal primordium.

Question 24

How is the sinus tubercle produced?

Answer 24

The caudal portion of the paramesonephric duct (uterovaginal primordium) projects into the urogenital sinus (bladder) to create the sinus tubercle.

Question 25

Formation of what is induced by the sinus tubercle? | What does it fuse to form?

Answer 25

Induces formation sinovaginal bulbs (endodermal outgrowths) which fuse to form the vaginal plate (precursor of vagina).

Question 26

How does the vaginal plate form the mature vagina?

Answer 26

Epithelium will proliferate, then re-canalize to form the lumen of the vagina.

Question 27

Prostate is from:

Answer 27

Pelvic part of urogenital sinus (endoderm) and splanchnic mesoderm (smooth muscle and CT).

Question 28

Bulbourethral glands are from:

Answer 28

Phallic part of urogenital sinus (endoderm) and splanchnic mesoderm (smooth muscle and CT).

Question 29

What hormone influences differentiation of male external genitalia?

Answer 29

DHT

Question 30

Genital tubercle in males becomes: In females:

Answer 30

Glans penis Glans clitoris

Question 31

Urethral (UG) folds in males becomes: (3) In females: (1)

Answer 31

Lateral walls of urethra Spongy urethra Penile raphe Frenulum of labia minora

Question 32

Labioscrotal swellings in men becomes: In females: (2)

Answer 32

Scrotum Labium majus Mons pubis

Question 33

What hormone influences differentiation of female external genitalia?

Answer 33

Estrogen

Question 34

What causes the completion of the spongy urethra?

Answer 34

Fusion of UG (urethral) folds.

Question 35

What is the navicular fossa and how is it formed?

Answer 35

It is the spongy urethra at the glans penis. | It is formed by surface ectoderm.

Question 36

Hypospadias is caused by:

Answer 36

Failure of the urogenital (urethral) folds close or the labioscrotal swellings to close.

Question 37

How is epispadias caused?

Answer 37

Improper location of genital tubercles to cloacal membrane. | Associated with bladder problems.

Question 38

What does the gubernaculum form in females?

Answer 38

The cranial part forms the ovarian l. and the caudal part becomes the round l. of the uterus.

Question 39

How is the broad l. formed?

Answer 39

Fusion of the paramesonephric ducts