Embryogenesis of Pituitary Gland and Reproductive Tract

Question 1

What is the stomodeum?

Answer 1

Part of the embryonic mouth.

Question 2

What is Rathke’s Pouch?

Answer 2

Part of the stomodeum.

Question 3

What is the infundibulum in the case of pituitary gland development?

Answer 3

A funnel-shaped structure at the base of the brain.

Question 4

In what direction does the infundibulum grow during pituitary gland development?

Answer 4

Down towards the mouth.

Question 5

In what direction does Rathke’s pouch grow during pituitary gland development?

Answer 5

Up towards the brain.

Question 6

What connects Rathke’s pouch to the stomodeum?

Answer 6

A stalk that regresses when Rathke’s pouch fuses with the infundibulum.

Question 7

What structure becomes the posterior pituitary gland?

Answer 7

The infundibulum.

Question 8

What structure becomes the anterior pituitary gland?

Answer 8

Rathke’s Pouch.

Question 9

What is the sella turcica?

Answer 9

The cavity in the sphenoid bone that houses the pituitary gland.

Question 10

What is the alternate name for the genital ridge?

Answer 10

The gonadal ridge.

Question 11

Where do primordial germ cells come from in mammals?

Answer 11

The gut, specifically the endoderm.

Question 12

How are primordial germ cells transported in birds?

Answer 12

The bloodstream.

Question 13

Where do primordial germ cells end up in mammals?

Answer 13

The gonadal/genital ridge.

Question 14

What does the genital/gonadal ridge become?

Answer 14

An ovary or a testis.

Question 15

What did the Jost (Yahst) experiment discover?

Answer 15

Removing the Mullerian ducts still leads to the embryo being female (in the absence of T and AMH stimulation).

Question 16

What are the two types of ducts found in the embryo?

Answer 16

1. Mullerian (paramesonephric) duct.
2. Wolffian (mesonephric) duct.

Question 17

What are the steps of sex determination in mammals?

Answer 17

1. Chromosomal sex.
2. Gonadal sex.
3. Hormonal sex.
4. Phenotypic sex.
5. Behavioral and/or Brain sex.

Question 18

How chromosomes are in one pair in mammals?

Answer 18

Two chromosomes.

Question 19

What determines sex in seaworms, fish, and reptiles?

Answer 19

The environment.

Question 20

What animals have multiple sex chromosomes?

Answer 20

Invertebrates, reptiles, insects.

Question 21

What animals are haplodiploid?

Answer 21

Bees and spiders.

Question 22

What does haplodiploid mean?

Answer 22

When either the male or female does not possess all of the chromosomes required to produce offspring.

Question 23

What are the sex chromosome combinations that result in males?

Answer 23

1. XY.
2. XXY.
3. XXYY.
4. XXXY.
   *2-4 results in males with impaired sperm production.

Question 24

What are the sex chromosome combinations that result in females?

Answer 24

1. XX.
2. XXX.

Question 25

What sex chromosome combination results in a female with incomplete ovarian development?

Answer 25

XO. *Turner's Syndrome.

Question 26

On which sex chromosome is the gene controlling testicular differentiation found on in mammals?

Answer 26

The Y-Chromosome.

Question 27

What does the SRY gene code for the production of?

Answer 27

Testis Determining Factor (TDF).

Question 28

What is the function of testis determining factor?

Answer 28

To act as a DNA-binding protein and a transcription factor.

Question 29

What does (TDF) cause to occur?

Answer 29

1. Development of Sertoli cells. 2. Anti-Mullerian Hormone to be produced by the Sertoli cells. 3. Primary sex chord/seminiferous tubule development.

Question 30

What occurs if the SRY gene is absent?

Answer 30

The secondary sex chords (egg nests) develop.

Question 31

What does Anti-Mullerian Hormone (AMH) do?

Answer 31

It prevents Mullerian ducts from forming.

Question 32

What are three other functions that the Y-chromosome codes for?

Answer 32

1. Long bone growth. 2. Androgen production. 3. Spermatogenesis.

Question 33

What are the male and female sex chromosomes in birds?

Answer 33

1. Males: ZZ*. 2. Female: ZW**. *The SRY gene is found on the Z chromosome. **The W chromosome determines sex.

Question 34

What does the testosterone secreted from the Leydig cells cause the formation of?

Answer 34

1. Epididymis. 2. Seminal vesicles. 3. Vas deferens.

Question 35

What are the steps of female tract development?

Answer 35

1a. No Testosterone. 1b. Wolffian ducts regress. 2a. No AMH. 2b. Mullerian ducts become the uterus, oviducts, cervix, and anterior vagina.

Question 36

What causes the differences in the uterine body between species?

Answer 36

The differences in the degree of fusion of the Mullerian ducts.

Question 37

What does the synthesis of DHT cause to form?

Answer 37

1. Penis. 2. Accessory sex glands (Prostate and Cowper's gland). 3. Scrotum.

Question 38

How do males and females differ in behavior?

Answer 38

1. Males are more aggressive when playing. 2. Males are better at spatial recognition and organizing things into a space.

Question 39

What happens if a female rat is given a dose of testosterone shortly after birth?

Answer 39

The female will fail to copualte or cycle as an adult.

Question 40

What part of the hypothalamus must be deactivated or removed for the hypothalamus to be defeminized?

Answer 40

The surge center.

Question 41

What are the steps of hypothalamus defeminization?

Answer 41

1. Testosterone crosses the blood-brain barrier. 2. Testosterone is converted into estradiol. 3. Estradiol deactivates the surge center.

Question 42

If estradiol is the hormone that causes defeminization, then why is the hypothalamus in females unaffected?

Answer 42

Females have a higher level of alpha-fetoprotein, which binds to estradiol and prevents it from crossing the blood-brain barrier.

Question 43

Where is alpha-fetoprotein produced?

Answer 43

1. Fetal liver. 2. Embryonic yolk sac.

Question 44

What is the biochemical classification of alpha-fetoprotein?

Answer 44

Glycoprotein.

Question 45

What tissue are undescended testis bound to?

Answer 45

The peritoneum.

Question 46

Are the testes full size when testicular descent occurs?

Answer 46

No.

Question 47

What is the heritability of cryptorchidism?

Answer 47

Highly heritable.

Question 48

What are the two types of cryptorchidism?

Answer 48

1. Unilateral: One testis fails to descend. Still fertile. 2. Bilateral: Both testes fail to descend. Sterile.

Question 49

What does cryptorchidism cause the germ cells to do?

Answer 49

Fail to multiply and then die. This leaves only sertoli cells in the seminiferous tubules.

Question 50

What type of cancer are cryptorchid individuals more likely to develop?

Answer 50

Testicular cancer.

Question 51

What is an inguinal hernia?

Answer 51

When a loop of the intestine is pulled down with the testis. *If not corrected, the loop may become necrotic and will kill the animal.

Question 52

How is an inguinal hernia detected?

Answer 52

Finding an abnormal bulge in the scrotum.

Question 53

What is a Freemartin?

Answer 53

A female who was exposed to T and AMH due to having a fused placenta with her male twin.

Question 54

When does the placental fusion occur, leading to a shared blood supply in Freemartins?

Answer 54

At the time of testis formation, but before ovarian formation.

Question 55

What is special about the blood of a freemartin and its twin?

Answer 55

Their blood is chimeric because they possess some WBCs that have XX sex chromosomes and some white blood cells that possess XY sex chromosomes.

Question 56

What is the frequency of Freemartinism?

Answer 56

93%+.

Question 57

What are the reproductive characteristics of Freemartins?

Answer 57

1. Ovatestis. 2. Adult male behavior. 3. No Mullerian ducts. 4. No anterior vagina. 5. Clitoral enlargement and protrusion. 6. No uterus, cervix, or oviducts.

Question 58

What are the characteristics of complete androgen insensitivity in an XY individual look-like?

Answer 58

1. No androgen receptors. 2. Have testes instead of ovaries. 3. No T response ---> No Wolffian duct development. 4. Mullerian duct regression due to AMH. 5. External genitalia is female.

Question 59

What are the characteristics of 5alpha reductase deficiency in an XY individual look-like?

Answer 59

1. Testis. 2. Mullerian duct regression due to AMH. 3. Wolffian duct development. 4. Pseudovagina and female external genitalia until puberty (become more phenotypically male). 5. No DHT.