Male Reproduction

Question 1

What is the main hormone of the male reproductive system?

Answer 1

Testosterone

Question 2

What is the major source of Testosterone?

Answer 2

Leydig Cells

Question 2

The secretion of both GnRH and LH are in turn controlled by what?

Answer 2

Negative feedback inhibition from the testosteone

Question 2

What are the 2 regions of the gonads in the embryo?

Answer 2

Cortical and Medullary

Question 2

Development of testes occurs when?

Answer 2

Week 7 of gestation

Question 2

What does the Mullerian duct develop?

Answer 2

fallopian tubes, uterus, and vagina

Question 2

What does the Wolffian duct develop?

Answer 2

epididymis, vas deferens, or seminal vessicle

Question 3

When do the embryonic gonads begin to convert cholesterol to pregnelone and eventually to active sex hormones?

Answer 3

about 7 week of conception

Question 4

Testosterone is secreted more by the ______, than the _____.

Answer 4

testes

adrenal cortex

Question 5

What regulates the activity o the leydig cells?

Answer 5

gonadotropin releasing hormone (GnRH) from the hypothalamus 
luteinizing hormone (LH) from the anterior pituitary

Question 6

Development of ovaries occur when?

Answer 6

Week 13 of gestation

Question 7

What 2 hormones act on the Gonads

Answer 7

LH and FSH

Question 8

Which hormone acts on the Leydig Cells?

Answer 8

LH

Question 9

FSH needs what to function?

Answer 9

Testosterone

Question 10

Which hormone acts on the Sertoli Cells?

Answer 10

FSH

Question 11

Estradiol is a type of what?

Answer 11

Estrogen

Question 12

What causes the production of the Mullerian inhibiting factor (MIF) by the sertoli cells of the embryo testes?

Answer 12

The srY gene

Question 13

The regression of the Mulleran duct to pevent deveopmen of female internal genitalia is exerted by?

Answer 13

The Mullerian inhibiting factor (MIF)

Question 14

When do the penis and scrotum begin to develop? the descent of the testes into the scrotum?

Answer 14

After onset of the Wolffian duct at about week 7

About month 7 or 8

Question 15

What is it called when the testes fail to descend into the scrotum by birth?

Answer 15

Cryptorchidism

Question 16

Pseudohermaphroditism can occur from what 2 ways?

Answer 16

1. The testes fail to produce MIF even when testosterone is present
2. The testes are unable to secrete testosterone due to congenitally lack of enzyme essential for its sythesis

Question 17

When is there a drastic drop in testosterone secretion?

Answer 17

The leydig cells remain dormant soon after birth

Question 18

What is the only source of androgens in the prepubertal years?

Answer 18

Adrenal Cortex

Question 19

At what age is the hypothalamus less sensitive to the low level of androgens?

Answer 19

Puberty (12-14 years old)

Question 21

Initiation of spermatogenesis requires what? Which is absolutely necessary?

Answer 21

FSH and testosterone | Testosterone

Question 23

What are the sexual characteristics of puberty?

Answer 23

1. Enlargement of scrotum to accommodate the enlargement of the testes 2. Growth of penis 3. Increase of the endoplasmic reticulum within the cells of the male reproductive glands 4. Hair growth - androgens 5. Acne - an increase in the activity of the sebaceous glands 6. Height growth spurt 7. Deepening of voice - enlargement of larynx 8. Growth of skeletal muscle - enlargement of larynx 9. Psychological effects - increased libido and aggression

Question 25

What causes the cessation of growth at about age 17?

Answer 25

androgens

Question 27

At what age is onset of puberty called precocious? How does this occur?

Answer 27

Before age 9 | Excessive secretion of testosterone in young males

Question 29

What is a true precocious puberty? What is this characterized by?

Answer 29

If the cause of excessive testosterone is due to a tumor in the hypothalamus or pituitary. Testicular enlargement, sperm production, and secondary sexual characteristics

Question 30

What causes pseudoprecocious puberty? What is it characterized by?

Answer 30

Excessive androgen secretion by the adrenal cortex or exogenous androgen. Secondary sexual characteristics, but no corresponding testicular enlargement and sperm production

Question 31

What is a treatment for precocious puberty?

Answer 31

Administration of an androgen receptor antagonist (i.e. cyproterone acetate) or removal of the source of hormone production

Question 32

What leads to reduced androgen secretion?

Answer 32

Testicular failure Castration Disorders of the hypothalamus or pituitary gland

Question 33

Why does testosterone production decrease in the presence of high estrogen concentrations?

Answer 33

Inhibition of gonadotropin secretion

Question 34

What creates a delay in the development of the male secondary sexual characteristics?

Answer 34

Androgen deficiency before puberty

Question 35

Androgen deficiency is characterized by what?

Answer 35

infantile external genitalia with no sperm production - no increase in muscle, enlargement of larynx or growth of pubic hair

Question 36

What is Klinefelter's syndrome?

Answer 36

A type of hypogonadism An extra X chromosome (XXY or XXXY) Infertility, failure to develop at puberty, gynecomastia (male breasts), womanly characteristics

Question 37

What could enhance fertility and sperm production?

Answer 37

Androgen replacement therapy or gonadotropin administration

Question 38

What are common side effects from misusing steroids? Risks? Treatment?

Answer 38

Infertility and testicular atrophy Cardiovascular disease and prostate carcinoma Androgen receptor antagonists administration

Question 39

Purpose of male contraceptives? Side effects?

Answer 39

Suppress sperm production - Regression of some secondary characteristics - Decrease in libido - Testicular atrophy - Oligospermia or azoospermia

Question 40

What is the process called to relocate the testes from Cryptorchidism?

Answer 40

Orchiopexy