Repro Embryology

Question 1

What are the 3 distinct germ layers of the developing embryo?

Answer 1

Ectoderm
Mesoderm
Endoderm

Question 2

What process developed the 3 germ layers?

Answer 2

Gastrulation

Question 3

In what week does the embryo fold?

Answer 3

4th week

Question 4

What migrates into the indifferent gonad of the developing embryo?

Answer 4

Primordial germ cells

Question 5

How is the sex of the baby determined?

Answer 5

By the karyotype of the primordial cells which is determined by the karyotype of the fertilised egg

Question 6

What does the indifferent gonad of the male develop into?

Answer 6

The testes

Question 7

What does the primitive duct system become in the male?

Answer 7

The epididymis and vas deferens

Question 8

What does the external genitalia of the male become?

Answer 8

The penis and scrotum

Question 9

What does the indifferent gonad develop into in the female?

Answer 9

The ovary

Question 10

What does the primitive duct system develop into in the female?

Answer 10

Uterus
Uterine tubes
Part of the vagina

Question 11

What does the external genitalia of the female become?

Answer 11

The vulva

Question 12

What is the common caudal opening of the developing urogenital and GI tracts?

Answer 12

The cloaca which is in the hindgut

Question 13

Describe the cloaca

Answer 13

Dilated pouch

Closed to the outside world by the cloacal membrane

Question 14

How can you tell that the cloacal membrane is meant to rupture?

Answer 14

The membrane that covers it has no mesoderm
This means it will not develop a blood supply
Avascular membranes are meant to rupture or die

Question 15

What is the urogenital ridge?

Answer 15

Region of mesoderm giving the embryonic kidney and gonad

Deeply embedded in the posterior wall of the embryo

Question 16

When do primordial cells undergo gametogenesis?

Answer 16

Once puberty has occurred

Question 17

Where do the primordial germ cells arise from?

Answer 17

The primitive yolk sac

Question 18

What is the sex-determining region of the Y chromosome?

Answer 18

The SRY region

Question 19

How does expression of the SRY region of the Y chromosome cause the indifferent gonad to develop?

Answer 19

The medullary cords become the seminiferous tubules

Question 20

What is studded in the epithelium of the seminiferous tubules?

Answer 20

The primordial germ cells

Ready to undergo gametogenesis when puberty occurs

Question 21

What happens to the indifferent gonad if there is no Y chromosome?

Answer 21

The medullary cords degenerate

The cortical cords become developed

Question 22

What are the primordial follicles?

Answer 22

Primordial germ cells form follicles in the developing ovary
These are the beginnings of the ovarian follicles
The ovarian follicles will develop into an oocyte at every cycle once puberty occurs

Question 23

How does expression of the SRY region cause the development of the duct system in the male?

Answer 23

Causes the gonads to develop
These produce testicular hormones
These hormones are what influence the development of the duct system in the male

Question 24

What hormones are produced by the testes to influence duct development? What are their actions?

Answer 24

Androgens - support Wolffian (mesonephric) ducts

Müllerian inhibiting hormone - suppresses the Müllerian (paramesonephric) ducts

Question 25

Describe the development of the duct system in a female

Answer 25

No testes No androgens - degeneration of the Wolffian ducts No MIH - development of the Müllerian ducts

Question 26

How does the testes descend from the kidneys to the scrotum?

Answer 26

Through the inguinal canal | Accompanied by the mesonephric duct

Question 27

What2 tissues contribute to the development of the vagina?

Answer 27

The paramesonephric ducts | Urogenital sinus endoderm

Question 28

What are the basic components of the indifferent external genitalia?

Answer 28

Genital tubercle Genital folds Genital swellings

Question 29

What for the genital folds surround and how is this formed?

Answer 29

The urogenital sinus | Formed by rupture of the cloacal membrane

Question 30

Which hormone drives the development of the male external genitalia?

Answer 30

Dihydrotestosterone

Question 31

Describe the development of the male external genitalia

Answer 31

Genital tubercle elongates - glans penis Genital folds fuse - spongy urethra Genital swellings fuse - scrotum

Question 32

Describe the development of the female external genitalia

Answer 32

No fusion Development of labia minora and majora Genital tubercle - clitoris

Question 33

Where does the gonad begin its development?

Answer 33

In the urogenital ridge - high up in the lumbar region

Question 34

What attaches the testis to the genital folds?

Answer 34

Gubernaculum

Question 35

What creates a passageway among the inguinal canal allowing the testes to descend?

Answer 35

Processus vaginalis

Question 36

What is the fate of the processus vaginalis?

Answer 36

Closes

Question 37

What happens if the processus vaginalis doesnt close?

Answer 37

Communication between the peritoneum and scrotum: | - indirect inguinal hernia

Question 38

What prevents further descent of the ovary?

Answer 38

The developed uterus

Question 39

What is the remnant of the gubernaculum in the female?

Answer 39

The round ligament