Male Reproductive Physiology

Question 1

How do fat cells play a role with estrogen?

Answer 1

They contain aromotase which converts testoerone to estradiol

Question 2

What are all of the substrates involved in steroid synthesis?

Answer 2

Cholesterol, pregenolone, progesterone, 17-OH-progesterone, Androstendione, testosterone, estradiol or dihydrotestosterone

Question 2

Do males typically have estrogen in circulation?

Answer 2

Yes

Question 3

What hormone stimulates androgen production?(2 points)

Answer 3

LH and FSH

Question 4

What type of receptor does LH bind to stimulate steroid synthesis? What is the specific reaction that initiates of the steroids?

Answer 4

It binds a G-protein linked receptor. It stimulates the conversion of ATP to cAMP via the action of adenylate cyclase. This in turn activates a kinase.

Question 5

How does the body maintain a high concentration of testosterone within the seminiferous tubules?

Answer 5

The sertoli cells produce androgen binding protein which maintains a high level of testosterone within the seminiferous tubules

Question 6

When do the development of the seminferous tubules take place during development?(2 points)

Answer 6

6 and 7 weeks gestation

Question 7

When does histologic differentiation of the feta ovary apparent during development?

Answer 7

6 moths gestation

Question 8

How many days does it take the precursors of spermatogenesis to be realeased into the seminiferous tubules?

Answer 8

74 days

Question 8

What secondary messenger is utilized by GnRH when it stimulates the release of LH?

Answer 8

GnRH binds to a cell surface receptor which increases the concentration of intracellular calcium

Question 8

Where do you get a peak of testosterone in males?(4 points)

Answer 8

A peak at 5 months gestation, a peak of at birth, a peak at puberty and another constant peak at adulthood

Question 9

Where are all of the substrates for steroid synthesis produced?(3 points)

Answer 9

Adrenal and Testes produce pregenolone, progesterone, 17-OH-progesterone, androgenstendione. Testis produce testosterone. Peripheral tissues produce estradiol and dihydrotestosterone.

Question 10

LH stimulates what cell? This cell is stimulated to perform what type of activity?

Answer 10

LH stimulates Leydig cells to produce androgens, mainly testosterone

Question 12

The androgens produced by the Leydig cells affect what target tissues and/or pathways?(2-3 points)

Answer 12

spermatogenesis, other target tissues and aromatization

Question 13

What is the rate-limiting step for steroid synthesis?

Answer 13

The action of Star: bringing cholesterol into the mitochondria

Question 15

How long does it take for spermatids/spermatozoa to pass through epididymis?( week range)

Answer 15

2-3 weeks

Question 16

If the sertoli cells were affected by heavy metal poisoning, what would be the hormone profile?(3 points)

Answer 16

Normal LH, normal testosterone but increase FSH

Question 17

How are the hormones GnRH and LH released in the body?

Answer 17

They’re released in pulses

Question 18

What type of relative concentration of testosterone is required for spermatogenesis?

Answer 18

A very high local concentration

Question 18

What is the average sperm count per mL?

Answer 18

50-150 million per mL

Question 19

What is the fat of testosterone?

Answer 19

90% of it is secreted. 0.5-3.0 % is unbound and it interacts with peripheral tissue. The bound part is bound to albumin and SHBG.

Question 20

What hormone regulates the secretion of LSH and FH?

Answer 20

gonadotropin releasing hormone

Question 20

What temperature is required for spermatogenesis?

Answer 20

requires a temperature below core body temperature

Question 21

What hormone is the major regulator of spermatogenesis and steroidogenesis? What hormone is the major regulator of this hormone? What type of hormone is this hormone?

Answer 21

Pituitary LH; GnRH; GnRH is a peptide hormone

Question 23

How do the spermatogonia move during division and differentiation to form spermatozoa?

Answer 23

They move up closer and closer to the tubule of the seminiferous tubules

Question 25

What number of sperm would lead to infertile by coitus?

Answer 25

Less than 4 million per mL

Question 27

What is the volume of the average ejaculate?

Answer 27

3.5 mL

Question 28

Why does the histologic differentiation of the fetal ovary take place at such a late time during development?

Answer 28

The granulosa cells haven’t organized around the dividing occytes to form the primary ovarian follicle

Question 29

Sexual dimorphism of the gonads begin at that time during development(2 points)

Answer 29

6 and 7 weeks gestation

Question 30

FSH stimulates what cell in the reproductive system? This cells is stimulated to perform what type of activity(4-7 points)

Answer 30

Sertoli cell; aromotase, growth factors for Leydig cels, growth factors for spermatogenesis, androgen binding protein and activin

Question 31

What number of sperm in semen would lead to decrease fertility?

Answer 31

Less than 20 million total per mL

Question 32

What are all of the cells involved in spermatogenesis?(7 points)

Answer 32

Dark Type A, Pale Type A, Primary Spermatocyte, Secondary Spermatocyte, Spermatids and Spermatozoa

Question 33

What are causes of primary hypogonadism?(2-6points)

Answer 33

x-radiation, chemtherapy, chromosomal abnormalities, infection(mumps, orthitis), trauma, drugs(spirnolactone, ketoconazole, alcohol)

Question 34

What are causes of secondary hypogonadism?(2-6 points)

Answer 34

Pituitary adenomas, benign tumors & cysts, metastases infiltrative disease, sarcoidosis, idiopathic congenital panhypopituitarism, Kallman Syndrome

Question 35

A well-developed male is found to have small testes, increased semen volume, and azoospermia. What is your differential diagnosis?

Answer 35

anabolic steroid use

Question 36

The evaluation of a male infertility patient shows that his testes were housed in the scrotum but were unusually firm to the touch and warm. His laboratory result indicates that he is azoospermic even though semen volume and serum testosterone concentration are within normal ranges. What do you think this patient’s problem is?

Answer 36

varicocele

Question 37

A couple is evaluated for infertility. The problem appears to be with the male. Examination reveals a normal testosterone and LH, but an initial semen analysis reveals a decreased semen volume and no detectable sperm. Past history reveals surgery to repair an inguinal surgery, so a fine needle biopsy is done of the right testis. The fine needle biopsy demonstrates normal sperm morphology and normal sperm motility. The most likely cause of the patient’s infertility is

Answer 37

disordered sperm transport

Question 38

In a 35-year-old father of two, who has smoked 4 packs of cigarettes a week since age 16, a failure of testosterone administration to lower LH and FSH levels might indicate:

Answer 38

a bronchogenic tumor secreting GnRH like peptide, but pulsatile