Embryology of the Reproductive System

Question 1

What happens during gastrulation?

Answer 1

Formation of the trilaminar disc

• invagination of the epiblast cells through the primitive streak to form the definitive endoderm and mesoderm

Question 2

What happens to the mesoderm during gastrulation?

Answer 2

Organised into 3 main groups: paraxial, intermediate and lateral plate

Question 3

What does the urogenital system arise from?

Answer 3

Intermediate mesoderm

Question 4

What is the cloaca?

Answer 4

Excretory ducts of both the urinary and genital system enter a common cavity

Question 5

When and where do primordial germ cells within the yolk sac migrate?

Answer 5

Migrate via dorsal mesentery to intermediate mesoderm (weeks 4-6)

Question 6

What forms genital ridges?

Answer 6

Coelomic epithelium proliferates and thickens

Question 7

What forms somatic support cells in the indifferent gonad?

Answer 7

Proliferating epithelium

Question 8

What is the role of somatic support cells in the indifferent gonad?

Answer 8

Envelop the primordial germ cells

Question 9

What happens in the ambisexual/bipotential phase?

Answer 9

The development of the genital ducts

• mesonephric (wollfian) duct
• paramesonephric (mullerian) duct

Question 10

Where do both genital ducts connect to?

Answer 10

Posterior wall of the urogenital sinus

Question 11

When does sexual differentiation occur?

Answer 11

From week 7 onwards

Question 12

What triggers male development?

Answer 12

Presence of SRY (sex determining region of Y) transcription factor

Question 13

In male development somatic support cells develop into….

Answer 13

Sertoli cells

Question 14

In males primary sex cords form ______/_______ _____, which engulf the ___.

Answer 14

In males primary sex cords form testis/medullary cords, which engulf the PGC’s.

Question 15

Rete testis connect the ________ ______ to the _____ _____.

Answer 15

Rete testis connect the mesonephric tubules to the testis cords.

Question 16

Between the ______ ______ and testis cords, a thickened layer of connective tissue forms the _____ _______.

Answer 16

Between the coelomic epithelium and testis cords, a thickened layer of connective tissue forms the tunica albuginea.

Question 17

SRY protein stimulates the formation of what?

Answer 17

Sertoli cells

Question 18

Sertoli cells secrete ___ which causes the degeneration of the __________ ____.

Answer 18

Sertoli cells secrete AMH which causes the degeneration of the paramesonephric duct.

Question 19

Sertoli cells stimulate _______ ____ to form Leydig cells. Leydig cells secrete _______.

Answer 19

Sertoli cells stimulate gonadal ridge to form Leydig cells. Leydig cells secrete testosterone.

Question 20

Testosterone induces the formation of which three structures?

Answer 20

Epididymis

Vas deferens

Seminal vesicles

Question 21

Dihydrotestosterone induces male specific ______ _________ development and _______.

Answer 21

Dihydrotestosterone induces male specific external genitalia development and prostate.

Question 22

What causes persistent mullerian duct syndrome

Answer 22

Mutations of AMH or AMH receptor genes

Paramesonephric ducts fail to regress

Question 23

Describe the presentation of persistent mullerian duct syndrome?

Answer 23

Present with

• uterus, vagina and uterine tubes
• testes in ovarian location
• male external genitalia

Question 24

The testes originate at ____ thoracic level and are pulled caudally by the _________.

Answer 24

The testes originate at 10th thoracic level and are pulled caudally by the gubernaculum.

Question 25

Failure to descend of one or both testes is \_\_\_\_\_\_\_\_

Answer 25

Failure to descend of one or both testes is cryptoorchidism

Question 26

3 accessory glands spout near the junction of the mesonephric duct and urethra during week 10, what are the three glands?

Answer 26

Prostate and bulbourethral glands Seminal vesicle

Question 27

The prostate sits _____ the bulbourethral glands

Answer 27

The prostate sits above the bulbourethral glands

Question 28

The seminal vesicle develops from what structure?

Answer 28

Mesonephric duct

Question 29

Female development occurs in the absence of what?

Answer 29

SRY transcription factor

Question 30

In female development germ cells differentiate into ______ and then into _______ \_\_\_\_\_\_\_\_.

Answer 30

In female development germ cells differentiate into oogonia and then into primary oocytes.

Question 31

In female development ______ \_\_\_\_\_\_ cells differentiate into granulosa cells and surround the _______ \_\_\_\_\_\_\_.

Answer 31

In female development somatic support cells differentiate into granulosa cells and surround the primary oocytes.

Question 32

Granulosa surrounding the primary oocytes form?

Answer 32

Primordial follicles in the ovary

Question 33

What are thecal cells?

Answer 33

Leydig homolog

Question 34

what influences the development of female external genitalia and development of paramesonephric ducts?

Answer 34

ovarian oestrogens from maternal sources

Question 35

What does the paramesonephric duct give rise to?

Answer 35

Uterine tubes Uterus Superior vagina

Question 36

What is a gartners cyst?

Answer 36

Remnant of mesonephric duct

Question 37

What are the three parts of the paramesonephric (mullerian) duct?

Answer 37

Cranial portion- opens into the coelomic cavity Horizontal portion- crosses the mesonephric duct Caudal portion- which fuses with the paramesonephric duct on the opposite side

Question 38

What does the fused portion of the paramesonephric ducts give rise to?

Answer 38

The uterus and superior vagina

Question 39

How is the vaginal lumen created?

Answer 39

By vacuolisation of the paramesonephric portion of the vagina and the sinuvaginal bulbs

Question 40

What are some of the complications that can occur in female development?

Answer 40

Double uterus & double vagina Double uterus Bicornate uterus Sepatated uterus Unicornate uteris Cervical atresia

Question 41

Between week \_-\_ the external genitalia are indistinguishable

Answer 41

Between week 4-7 the external genitalia are indistinguishable

Question 42

How is the spongy urethra formed?

Answer 42

Spongy urethra forms by proximal to distal zipping of urethral groove

Question 43

How is the spongy urethra completed at the distal penis?

Answer 43

Ectodermal ingrowth at tip of glans which meets spongy urethra

Question 44

How is the prepuce formed?

Answer 44

Circular ingrowth of the ectoderm around the periphery of the glans

Question 45

What is hypospadias?

Answer 45

External urethral opening lies in an abnormal position along the ventral aspect of the penis

Question 46

Answer 46