Male Reproductive Physiology

Question 1

In the seminiferous tubules; Testosterone (T) is concentrated by binding to what?

Answer 1

ABP (Androgen Binding Protein)

Question 2

In the peripheral circulation, Testosterone (T) is carried by what?

Answer 2

SHBG (Steroid Hormone Binding Globulin) & Albumin

Question 3

What are the two ways in which LH promotes Pregnenolone synthesis?

Answer 3

1) Increases affinity of the P450scc enzyme for cholesterol (Cholesterol Desmolase)
2) Stimulates synthesis of P450scc enzyme (long-term action)

Question 4

When does fetal production of testosterone begin?

Answer 4

~14-15 weeks gestation

Question 5

What plays an important role in the induction of puberty?

Answer 5

DHT (dihydrotestosterone); this has a higher affinity for the binding of androgen receptors

Question 6

What is the primary form of testosterone and its metabolities, once excreted into the urine?

Answer 6

17-ketosteroids

Question 7

What are the fetal actions of testosterone?

Answer 7

They cause the testes to descend during the last 2-3 months of pregnancy

Question 8

What can be used to treat benign prostatic hyperplasia and hair loss in males?

Answer 8

1) 5a-reductase inhibitors

2) Male hair growth and prostate gland growth depend on DHT rather than testosterone

Question 9

Leydig Cell is stimluated via?

What are its main products?

Answer 9

1) Stimulated via: LH

2) Produces: Testosterone

Question 10

Sertoli Cell:
1) Stimulated via?

2) Produces?

Answer 10

1) Testosterone and FSH

2) Inhibin, ABP, & Aromatase

Question 11

What is a key feature of Sertoli cells in regards to estrogen and testosterone production?

Answer 11

It produces Aromatase which converts Testosterone into Estradiol 17-B

Question 12

In regards to Spermatogenesis, how long does the entire process take?

Also, when does a new group of cells enter maturation?

Answer 12

1) ~74 days

2) A new group of cells enters maturation ~ 16 days

Question 13

What process occurs in the epididmyis that allows sperm to increase their motility?

Answer 13

Decapacitation; involves the sperm adding molecules to the membrane of the sperm to prevent the acrosomal reaction from occuring prior to contant with the egg

Question 14

What are the two functions in which Prostaglandins aid in fertilization?

Answer 14

1) React with the female cervical mucus to make it more receptive to sperm movement (thin the cervical mucus)
2) Cause backward, peristaltic contractions, moving the sperm toward the ovaries

Question 15

What is the role of Viagra?

Answer 15

It is a Type 5 PDE inhibitor; preventing the breakdown of cGMP –> GMP (inhibits type 5 phosphodiesterase)

Question 16

What striated muscle are responsible for Ejaculation?

Answer 16

Bulbospongiosus & Ischiocavernosus M.

Question 17

During what weeks are the gonads considered to be bipotential (neither male or female)?

Answer 17

During the first five weeks

Question 18

During what gestational weeks do the testes begin to develop in genetic males?

Answer 18

6-7 weeks

Question 19

During what gestational weeks do the ovaries begin to develop in genetic females?

Answer 19

Week 9

Question 20

What is the main function of the prostate gland in regards to semen production?

Answer 20

It produces a slight alkaline fluid that neutralizes the acidity of the other seminal fluids during ejaculation; enhances the motility and fertility of the sperm

Question 21

What are the two main differences between the male and female reproductive tract?

Answer 21

1) Male tract: Has continuous lumen from seminiferous tubule to penile urethra
2) Male Tract: Urinary tract connects to the sexual reproductive tract

Question 22

The nitric oxide produced from cavernous nerves, as a result of sexual stimuli, acts on smooth muscle located where?

Answer 22

Vascular smooth of the helicine arteries

Question 23

What three events occur during Capacitation of the Sperm?

Answer 23

1) Uterine and Fallopian tubes wash away inhibitory factors
2) Loss of cholesterol that had been built up in the acrosome; head of the sperm is much weaker
3) Sperm is more permeable to Ca2+; greater motility

Question 24

In regards to the acrosomal reaction, what is the function of hyaluronidase in sperm?

Answer 24

Hyalurondiase: Depolymerizes the hyaluronic acid polymers that keep the ovarian granulosa cells together

Question 25

What is the result of testosterone deficiency during 2-3 months of gestation?

Answer 25

Varying degrees of ambiguity in the male genitalia & male pseudohermaphroidism

Question 26

What is male pseudohermaphroidism?

Answer 26

Hermaphroditism refers to a discrepancy between the morphology of the gonads and that of the external genitalia. In male pseudohermaphroditism, the genotype is male (XY) and the external genitalia are imcompletely virilized, ambiguous, or complete female. If gonads are present, they are testes.

Question 27

What is the result of testosterone deficiency during the third trimester?

Answer 27

Cryptochordism (lack of testicular descent) along with micropenis

Question 28

What is Eunuchoidism?

Answer 28

Persistence of prepubertal characteristics & often presence of characteristics typical of the opposite sex

Question 29

What is etiology and some symptoms of Kallman’s Syndrome?

Answer 29

Genetic disorder, causes by failure of GnRH neurons to migrate into the hypothalamus.

Symptoms: Delayed or absent puberty and impaired sense of smell

Question 30

What is the etiology Klinefelter Syndrome?

Answer 30

XXY Karyotype; increased gonadotropins & decreased levels of androgen production

Question 31

What is the resulting pathology of Klinefelter Syndrome?

Also, what is another name for Klinefelter Syndrome?

Answer 31

1) AKA: Seminiferous Tubular Dysgenesis; seminiferous tubules are largely destroyed

Question 32

What type of hormones are produced in a germinal epithelial tumor?

Answer 32

None

Question 33

Loss of sexual activity typically occurs?

Answer 33

Age 68-70 y/o