Development of reproductive system

Question 1

What gene determines sex and which gender is it present in?

Answer 1

SRY gene present in males but absent in females

Question 2

Which cell type do the external genitalia develop from?

Answer 2

Intermediate mesoderm (same as urinary system)

Question 3

What do leydig cells do?

Answer 3

Produce testosterone in the presence of Luteinizing hormone

Question 4

Why does SRY gene presence determine sex?

Answer 4

Because it makes cells in the gonads differentiate into testis.

Question 5

Name 3 cell types cells in the testis differentiate into

Answer 5

1. Leydig cells.
2. Sertoli cells
3. Spermatogonia

Question 6

Name two effects of the testosterone produced by the leydig cells?

Answer 6

1. Induces mesonephric duct (wolfing duct) to form male genital tract
2. Testosterone is converted to dihydrotestosterone which is responsible for differentiation of the external genitalia.

Question 7

State 3 ways differentiation produces the external genitalia

Answer 7

1. Genital tubercle become the penis
2. Genital swelling becomes the scrotum
3. Urethra epithelium becomes the prostate.

Question 8

Which two hormones do Sertoli cells produce to form spermatozoa and male genital tract?

Answer 8

Androgen binding factor and Mullerian inhibiting substance

Question 9

What does androgen binding factor do?

Answer 9

Turns spermatogonia into spermatozoa (testosterone also contributes to this)

Question 10

What does mullerian inhibiting substance do?

Answer 10

Convert paramesonephric ducts into degenerated tissue

Question 11

What is the tunica albuginea?

Answer 11

Covering around the scrotum

Question 12

How does absence of SRY gene cause ovary formation?

Answer 12

Causes medulla to degenerate while the cortex remains and proliferates

Question 13

What embryological feature forms the gonads?

Answer 13

The allantois

Question 14

What are the primitive sex cords derived from and what induces their development?

Answer 14

Derived from mesonephros and overlying coelomic epithelium
Induced by primordial germ cells migrating from yolk sac (connected to hinfgut because the structures are continuous) to gonadal ridges via dorsal mesentery of hindgut (around 6th week)

Question 15

What does the metanephros become in the adult?

Answer 15

The functional kidney

Question 16

Which two structures is the functional kidney derived from?

Answer 16

Ureteric bud
(Metanephric mass) intermediate mesoderm

Question 17

Where is the site of gonad and metanephros development?

Answer 17

Urogenital ridge
(gonads - medial)
(metanephros - lateral)

Question 18

What 2 cell types is the gonadal ridge derived from?

Answer 18

Mesenchyme (derived from mesoderm and goes on to form connective tissue)
Germinal epithelium

Question 19

What does gonadal ridge become?

Answer 19

Testis or ovaries

Question 20

State the ducts that persist to form the male genital tract

Answer 20

Mesonephric duct (aka Wolffian duct)

Question 21

State the duct that persists to form the female genital tract

Answer 21

Paramesonephric duct

Question 22

What 3 structures does the urogenital sinus differentiate into in males in presence of mullerian inhibiting substance?

Answer 22

Prostate, urethral and bulbourethral glands

Question 23

What 5 structures does the mesonephric duct differentiate into in males in the presence of mullerian inhibiting substance?

Answer 23

rete testis
efferent ductules
epididymis 
vas deferens
seminal vesicle

Question 24

What 3 structures does the medulla of the gonadal ridge differentiate into after the cortex has degenerated?

Answer 24

Rete testis, seminiferous tubules and tunica albuginea

Question 25

What is the main defect seen in the development of the male genital tract?

Answer 25

Cryptorchidism - 'Abnormal testicular development' - testis don't migrate into the scrotum following the gubernaculum and into the processes vaginalis that forms.

Question 26

Why does cryptorchidism cause infertility

Answer 26

Suboptimal temperature

Question 27

Which structure forms the female genital tract?

Answer 27

The paramesonephric duct (aka mullerian duct)

Question 28

What 3 structures does the urogenital sinus differentiate to form?

Answer 28

1. Paraurethral glands 2. Greater vestibular glands 3. Lower genital tract

Question 29

Describe the greater vestibular glands and their function

Answer 29

Female equivalent of bulbourethral glands. They secrete mucus to lubricate the vagina and are posterior and lateral of the vaginal opening

Question 30

Which 3 structures does the paramesonephric duct differentiate into?

Answer 30

1. Uterine tube 2. Uterus 3. Vagina

Question 31

Which hormone is responsible for the growth and fusion of genital folds to enclose the urethra within the penis?

Answer 31

Dihydrotestosterone

Question 32

What is the cause of hypospadias or epispadias?

Answer 32

Failure of fusion of genital folds (occurs around week 9)

Question 33

Describe the difference between hypospadias and epispadias

Answer 33

Hypospadias - urethra opens onto the ventral surface of the penis Epispadias - urethra opens onto the dorsal surface

Question 34

Where do the scrotal raphe originate from?

Answer 34

The line of fusion

Question 35

Approximately when does development of female external genitalia occur?

Answer 35

Week 11

Question 36

Describe the development of the 3 parts of the female external genitalia

Answer 36

Glans clitoris from the genital tubercle Labia minor from the genital folds Labia major from the genital swellings

Question 37

What is the cause of Turner's syndrome?

Answer 37

Absence of X chromosome in females

Question 38

What three processes don't occur in the absence of an X chromosome in females?

Answer 38

1. Primordial germ cells degenerate 2. Gonads do not differentiate 3. Genitalia do not mature

Question 39

What is the cause of Klinefelter syndrome?

Answer 39

An extra X chromosome in males

Question 40

Describe De La Chapelle syndrome

Answer 40

Abnormal presence of SRY gene in an X chromosome so male external genitalia develop in a genetic female

Question 41

Describe androgen insensitivity syndrome

Answer 41

Failure of testosterone receptors in genetic males so differentiation not induced so default female genitalia develop instead