Embryology of Reproductive System

Question 1

Gastrulation begins with…

Answer 1

Formation of primitive streak

Question 2

Describe the process of gastrulation

Answer 2

Conversion of the epiblast from a bilaminar disc into a trilaminar embryonic disc consisting of a definitve mesoderm and endoderm

Question 3

Mesoderm is organised into 3 groups. What are they?

Answer 3

Paraxial plate
Intermediate plate
Lateral plate

Question 4

The urogenital system arises from which germ cell layer?

Answer 4

Intermediate mesoderm

Question 5

Which common cavity do excretory reproductive ducts open into during development?

Answer 5

Cloaca

Question 6

Describe the formation of genital ridges

Answer 6

Proliferation of coelomic epithelium into somatic support cells, which envelope primordial germ cells (origins of sperm and oocytes)

Question 7

Describe the formation of the indifferent gonad

Answer 7

Two genital ridges penetrate and invade the underlying mesenchyme forming finger-like primitive sex cords

Question 8

State the two genital ducts formed during the ambisexual phase of development

Answer 8

Mesonephric (wolfian) duct - MALES

Paramesonephric (mullerian) duct - FEMALES

Question 9

What structure do the genital ducts connect to?

Answer 9

Urogenital sinus

Question 10

Sexual differentiation occurs from week _ onwards

Answer 10

7

Question 11

Male development is triggered by the absence/presence of sex determining region of Y transcription factor

Answer 11

Presence

Question 12

Somatic support cells develop to form what cells? What are they stimulated by?

Answer 12

Sertoli cells

SRY transcription factor

Question 13

Which structure connects the mesonephric tubules to the testis cords?

Answer 13

Rete testis

Question 14

What exists between coelemic epithelium and testis cords?

Answer 14

Tunica albuginea

Thickened layer of CT

Question 15

List the functions of sertoli cells in development

Answer 15

Secrete anti-Mullerian harmone (AMH) causing degeneration of paramesenephric duct
Stimulate gonadal ridge cells to form Leydig cells

Question 16

What is the function of Leydig cells?

Answer 16

Production of testosterone –> dihydrotestosterone

Question 17

The production of testosterone stimulates which male structures to form?

Answer 17

Epididymis
Vas deferens
Seminal vesicles

Question 18

The production of dihydrotestosterone stimulates which male structures to form?

Answer 18

External genitalia

Prostate

Question 19

Which spinal level do the testis orginate from?

Answer 19

T10

Question 20

Name the ligament which pulls the testis caudally during development

Answer 20

Gubernaculum

Question 21

Failure to descend one or both testis is known as…

Answer 21

Cryptorchidism

Question 22

List the 3 male accessory glands formed during development and the relative origin of each

Answer 22

Prostate (endoderm)
Bulbourethral glands (endoderm)
Seminal vesicles (mesonephric duct)

Question 23

Female development is triggered by the absence/presence of sex determining region of Y transcription factor

Answer 23

Absence

Question 24

Primary oocytes are differentiated from which cells?

Answer 24

Germ cells

Question 25

Granulosa cells are differentiated from what cells?

Answer 25

Somatic support cells

Question 26

Primordial follicles are formed from...

Answer 26

Primary oocytes surrounded by granulosa cells

Question 27

Paramesonephric ducts are formed under the influence of what sex harmone?

Answer 27

Ovarian oestrogens

Question 28

Paramesonephric ducts give rise to which structures of the female reproductive system?

Answer 28

Uterine tubes Uterus Superior vagina

Question 29

List the 3 main parts of a paramesonephric duct

Answer 29

``` Cranial portion (opens into coelomic cavity) Horizontal portion (crosses mesonephric duct) Caudal portion (fuses paramesonephric duct on opposite side) ```

Question 30

What is the function of the uterovaginal canal

Answer 30

Fused caudal portion of paramesonephric ducts give rise to uterus and superior vagina

Question 31

How is the paramesonephric portion of vagina, sinuvaginal bulbs and fornices formed?

Answer 31

Vacuolization of vaginal lumen

Question 32

How is the spongy urethra in males formed?

Answer 32

Proximal to distal zipping of urethral groove

Question 33

Which germ cell layer forms the tip of the glans penis and the foreskin?

Answer 33

Ectoderm

Question 34

What is hypospadias?

Answer 34

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