Session 2: Embryology

Question 1

Where do activities related to the gonad occur?

Answer 1

Mesoderm

Question 2

What is an overview of the reproductive system development

Answer 2

-Primordial germ cells undergo mitosis to become indifferent gonad.

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Question 3

What is the urogenital ridge?

Answer 3

-Region of intermediate mesoderm giving rise to both the embryonic kidney and gonad

Question 4

Where is the indifferent gonad derived from?

Answer 4

-Gonad (indifferent) is derived from the intermediate mesoderm plus primordial germ cells

Question 5

What are the primordial germ cells?

Answer 5

• Special population
• Seed for the next generation
• Allocated shortly after initiation of the current generation
• Arise in the yolk sac and migrate into the retroperitoneum along the dorsal mesentery

Question 6

Which genes drives development of male gonads?

Answer 6

Primordial germ cells carry the Y chromosome. SRY gene drives development of the male

Question 7

What leads to the develop of female gonad?

Answer 7

Absence of the Y chromosome in the primordial germ cells

Question 8

Which ducts are kept by the male?

Answer 8

Mesonephric ducts

Question 9

Which ducts are kept by the female?

Answer 9

Paramesonephric ducts

Question 10

Both mesonephric ducts and paramesonephric ducts develop in both male and female embryos. True/False

Answer 10

True

Question 11

Where do both mesonephric and paramesonephric ducts end?

Answer 11

They both end at the urogenital sinus part of the cloaca.

Question 12

What does the fate of the ducts depend on?

Answer 12

Whether there is a functional testis

Question 13

What occurs in a normal male with regards to the fate of the ducts?

Answer 13

• Testis producing Mullerian inhibiting hormone suppressing paramesonephric (Mullerian) duct development.
• Testis producing androgens supporting mesonephric (Wolffian) duct.

Question 14

What occurs in a normal female with regards to the fate of the ducts?

Answer 14

• No testis producing Mullerian inhibiting hormone so no suppression of the paramesonephric (Mullerian) duct development
• No testis producing androgens so mesonephric (Wolffian) duct degenerates

Question 15

What happens when things go wrong and exogenous androgens interact with the ducts?

Answer 15

• Wolffian (mesonephric) duct is supported
• No testis so no mullein inhibiting hormone
• Mullerian ducts develop as a result

Question 16

What happens in androgen insensitivity syndrome?

Answer 16

• Receptors for testosterone don’t work
• Wolffian (mesonephric) ducts don’t survive
• Mullerian inhibiting hormone persists so paramesonephric ducts degenerate

Question 17

What is the first purpose of the mesonephric duct?

Answer 17

-Acts as a duct for the embryonic kidney

Question 18

What does the mesoneprhic duct drain into?

Answer 18

Urogenital sinus

Question 19

What forms the urinary bladder?

Answer 19

Urogenital sinus

Question 20

What is the final step in the development of the mesonephric duct?

Answer 20

• It is converted into the vas deferens and epididymis

- Migrates with the testis as it descends

Question 21

What do the paramesonephric ducts appear as?

Answer 21

Invaginations of the epithelium of the urogenital ridge

Question 22

What happens to the paramesonephric ducts caudally?

Answer 22

Make contact with the Cloaca

Question 23

What happens to the paramesonephric ducts cranially?

Answer 23

Open into the abdominal cavity

Question 24

What are the basic components of the external genitalia in the indifferent stage of development?

Answer 24

• Genital tubercle
• Genital folds
• Genital swellings

Question 25

What happens to form the external genitalia in the male?

Answer 25

- Genital tubercle elongates and the genital folds fuse to form the spongy urethra - Genital tubercle develops into the glans penis - Influenced by testis-derived androgen hormones

Question 26

What happens to form the external genitalia in the female?

Answer 26

- Development of the labia majora and labia minora - Genital tubercle develops into clitoris - Urethra opens into the vestibule

Question 27

How does the descent of the ovary occur?

Answer 27

- Gubernaculum attaches ovary inferiorly to labio-scrotal folds - Ovary descends to the pelvis - Uterus has developed and prevent further descent - Round ligament of the uterus inguinal canal