Male Repro

Question 1

How does LH in males stimulate testosterone synthesis?

Answer 1

Gs coupled receptor that stimulates transcription of genes for 17 beta hydroxysteroid dehydrogenase

Question 2

What does P-450 aromatase do in males?

Answer 2

Convert testosterone to estradiol to support spermatogenesis

Question 3

What does FSH on sertoli cells stimulate?

Answer 3

• ABP
• P-450 aromatase
• 5a-reductase
• Growth factors
• Inhibins
• Activins

Question 4

What is the carrier protein of androgens in the seminiferous tubule lumen?

Answer 4

Androgen-binding protein

Question 5

What are the androgen systemic effects?

Answer 5

• Masculization during development
• Growth on skeletal muscle (anabolic steroid)
• Inhibit adipose deposition
• CNS effect increase aggression and libido

Question 6

What do androgens bind to?

Answer 6

Androgens receptors that are bound to Hsp90

Question 7

What is the role of androgens in repro?

Answer 7

Support spermatogenesis

Question 8

What happens to the hormones when a male is castrated?

Answer 8

An excess of FSH and LH because there is no target. This turns off GnRH from the pituitary

Question 9

The first division in spermatogenesis is…

Answer 9

Mitotic division to make a type A and type B cell

Question 10

What is the second division in spermatogenesis…

Answer 10

Type B cells divide mitotically several times before meiosis. They are now primary spermatocytes

Question 11

What is spermiogenesis?

Answer 11

Series of functional and morphological changes to produce spermatozoa

Question 12

What are important changes in spermiogenesis?

Answer 12

• Flagellum
• Mitochondrial midpiece for energy for motility
• Acrosome cap important for fertilization
• Condensation of the nucleus and disulfide crosslinking of DNA for protection
• Remove excess cytoplasm

Question 13

What do sertoli cells do?

Answer 13

-Respond to FSH and promote proliferation of spermatogoneia
-Make 5a reductase
-Secrete ABP
=Secrete inhibin for feedback
-Gap junction communicate with spermatozoa
-Phagocytose residual body
- Blood testis barrier so sperm not killed

Question 14

Is number of spermatogonia going through spermatogenesis hormone dependent?

Answer 14

No. Hormones will not increase spermatogenesis

Question 15

What determines the number of spermatogonia going through spermatogenesis?

Answer 15

Number of Sertoli cells ( the more the merrier)

Question 16

How do male hormones sustain spermatogenesis?

Answer 16

They secrete survival factors to sertoli cells with communicate this to the spermatids which otherwise have high levels of Bax/Bac which would push it towards apoptosis

Question 17

How can you measure daily sperm production?

Answer 17

Measuring testicular size

• number of sertoli cells
• number of spermatozoa

Question 18

What temperature is optimal for sperm development?

Answer 18

2-4 degrees celsius below body temperature (why they external to body)

Question 19

How do the scrotum thermoregulate?

Answer 19

• Acts as a thermosensor and causes feedback to hypothalamus changing behavior (sweat, panting etc)
• Counter-current heat exchange from pampiniform plexus

Question 20

What is the pampiniform plexus?

Answer 20

Artery with a bunch of veins around it to exchange heat

Question 21

What is the third division of spermatogonia?

Answer 21

Asymmetric meiosis generating secondary spermatocytes

Question 22

What is the fourth division of Spermatogenesis?

Answer 22

Meiosis II. Secondary spermatocytes become spermatids

Question 23

What is the end result of spermatogenesis?

Answer 23

Spermatids that are haploid

Question 24

How much sperm is produced daily?

Answer 24

Millions of sperm are made but only about 1/2 survive

Question 25

What is the gubernaculum?

Answer 25

Ligament formed during gestation that grows between the testes and developing scrotal sac

Question 26

What allows for scrotal descent?

Answer 26

Alternating growth and regression phases of the gubernaculum pull it through the inguinal canal into the scrotum

Question 27

What is a cryptorchid?

Answer 27

Failure to relocate the testes but they can still produce hormones