4: Embryology of the reproductive system

Question 1

Which germ layer is most involved in the renal and urogenital systems?

Answer 1

Mesoderm

Question 2

In the very initial stages of development, which two germ layers exist?

Answer 2

Epiblast

Hypoblast

Question 3

Which structure do mesoderm cells migrate through to form the middle germ layer?

Answer 3

Primitive streak

Question 4

After the mesoderm forms, what three sections does it split into?

Answer 4

Paraxial (medial)

Intermediate

Lateral

mesoderm

Question 5

After migrating through the primitive streak, the mesoderm forms paraxial, intermediate and lateral sections.

What are the two subdivisions of the lateral mesoderm?

Answer 5

Visceral

Parietal

Question 6

The urogenital system develops from the ___ mesoderm.

(paraxial, intermediate, lateral, visceral, parietal)

Answer 6

intermediate mesoderm

just remember this

Question 7

Which type of mesoderm does the urogenital system develop from?

Answer 7

Intermediate mesoderm

Question 8

Early in development, which common cavity do both the renal and genital systems have?

Answer 8

Cloaca

Question 9

From cranial to ventral, what are the parts of the early renal tract called?

Answer 9

Pronephros

Mesonephros

Metanephros

finishing at the cloaca

Question 10

What does the term indifferent gonad mean?

Answer 10

You can’t tell if the embryo is male or female

Question 11

Which type of cell differentiates into the male and female gametes?

Answer 11

Primordial germ cell

‘gamete mother cell’

Question 12

In weeks 4 - 6 of development, the primordial germ cells migrate from the ___ ___ to the ___ ___.

Answer 12

yolk sac

to the sex cords

through the dorsal mesentery

Question 13

Which two ducts are formed by the embryo in Weeks 4 - 6?

Answer 13

Mesonephric (Wollfian) duct

Paramesonephric (Mullerian) duct

Question 14

What is the other name for the mesonephric duct?

Answer 14

Wollfian duct

Question 15

What is the other name for the paramesonephric duct?

Answer 15

Mullerian duct

Question 16

Which ducts develop into the reproductive tract in

a) males
b) females?

Answer 16

a) Mesonephric duct

b) Paramesonephric duct

Question 17

In terms of sex chromosomes, what determines if an embryo will be male or female?

Answer 17

Male - presence of sex-determining region of Y chromosome

Female - absence of sex-determining region of Y chromosome

Question 18

What are the two germ cells found in males?

What do they do?

Answer 18

Sertoli cells - sperm support cells; during development they secrete Anti-Mullerian hormone (AMH)

Leydig cells - testosterone-producing cells

Question 19

What type of male germ cell secretes Anti-Mullerian hormone (AMH)?

Answer 19

Sertoli cells

Question 20

What is the function of AMH?

Answer 20

Causes degeneration of Mullerian tract (paramesonephric duct) in males

Question 21

Which structure connects the mesonephric ducts to the sex cord in males?

What is the sex cord called?

Answer 21

Rete testis

Testis cord

Question 22

What hormone do Leydig cells produce?

Answer 22

Testosterone

Question 23

What is the function of testosterone during development?

Answer 23

Stimulates development of the male reproductive tract

Question 24

What is the path of sperm from the testes to the penis?

Answer 24

Seminiferous tubules

Epididymis

Rete testis

Vas deferens

Spermatic –> Ejaculatory ducts

Prostatic –> Spongy urethra

Question 25

Which specific type of testosterone stimulates the development of the male's external genitalia?

Answer 25

**Dihydrotestosterone**

Question 26

In which condition does a male present with **male external genitalia**, but **both male and female reproductive tracts?**

Answer 26

**Persistent Mullerian Duct syndrome**

Question 27

Mutations in the genes for which **hormone** causes **persistent Mullerian duct syndrome?**

Answer 27

**AMH** Anti-Mullerian hormone

Question 28

Which hormones trigger the development of the ## Footnote **a) male external genitalia** **b) epididymis, vas deferens and seminal vesicles?**

Answer 28

**a) Dihydrotestosterone** **b) Testosterone**

Question 29

Where do the **testes** originate during development?

Answer 29

**Posterior abdominal wall, 10th thoracic level**

Question 30

Which **developmental structure** pulls the **testes inferiorly** during development?

Answer 30

**Gubernaculum**

Question 31

Which **layers** must the testes pass through on their way to the **scrotum**?

Answer 31

**Parietal peritoneum** **Transversalis fascia** **Transversus abdominis** **Internal oblique** **External oblique** **Superficial fascia**

Question 32

What are the **three layers** of the **spermatic cord** and which **abdominal layers** are they derived from?

Answer 32

**Internal spermatic fascia:** from **transversalis (deep) fascia** **Cremasteric fascia:** from **internal oblique** **External spermatic fascia:** from **superficial fascia**

Question 33

Which structures do the testes pass through to reach the scrotum?

Answer 33

**Deep and superficial inguinal rings**

Question 34

What condition is caused by **failure of one or both testes to descend**?

Answer 34

**Cryptorchidism**

Question 35

Which **three accessory** **glands** develop in the male?

Answer 35

**Prostate gland** **Bulbourethral gland** **Seminal vesicle**

Question 36

In which circumstances does an indifferent embryo develop a **female genital tract**?

Answer 36

**Absence of Y chromosome**

Question 37

Which **female germ cells** a) support the follicles and convert androgens to oestrogen b) convert pregnenolone to androgens?

Answer 37

**a) Granulosa cells** **b) Theca cells**

Question 38

Which **hormone** triggers the development of the **female external genitalia** and **paramesonephric ducts**?

Answer 38

**Oestrogen**

Question 39

**Oestrogen** triggers the development of which duct in the female?

Answer 39

**Paramesonephric (Mullerian) duct**

Question 40

Which aspects of the **internal female genitalia** develop from the **paramesonephric ducts?**

Answer 40

**Uterine tubes** **Uterus** **Superior vagina** Ovaries descend from posterior abdominal wall in a similar manner to the testes

Question 41

The **paramesonephric ducts** ___ to form the uterus and superior vagina.

Answer 41

**fuse**

Question 42

What is **hypospadias**?

Answer 42

**Abnormal position of external urethral orifice**

Question 43

Which **germ layer** is the **external genitalia** of the female formed from?

Answer 43

**Endoderm**