Male Repro

Question 1

What are the 4 accessory glands of the male reproductive system?

Answer 1

Seminal vesicles, prostate gland, bulbourethral (Cowper’s) glands, and the penis

Question 2

The seminiferous tubules are lined with what two populations of cells?

Answer 2

Germinal epithelium (spermatogenesis takes places)

Sertoli cells (supportive or “nurse” cells) - narrow cells extending from the base of the seminiferous tubule to the lumen

Question 3

What is spermatogenesis?

Answer 3

Process of spermatogonia (stem cells) –> spermatozoa

Question 4

What is the blood-testis barrier and what does the blood-testis barrier divide?

Why is it important?

Answer 4

Sertoli cell cytoplasmic processes that form occluding junctions (separates basal compartment - containing spermatogonia - from adluminal compartment - containing cells undergoing meiosis)

Spermatogonia from primary spermatocytes

Meiosis in primary spermatocytes generates cells that can be recognized as foreign by the immune system (due to rearrangement of xsomes and the appearance of new cell surface markers) - B-T barrier needed to keep these “new” cells away from the immune system / Also imp to maintain high local concentration of testosterone from Leydig cells

Question 5

What is spermatogenesis?

Where does it take place?

What are the four phases?

Answer 5

Subdivision of spermatogenesis: Conversion of spermatids –> spermatozoa

Process takes places while spermatids are embedded in Sertoli cells’ cytoplasm

Divided into 4 phases:

1. Golgi phase (hydrolytic enzymes are sorted from the golgi apparatus to the acrosomal vesicle)
2. Cap phase (acrosomal cap forms)
3. Acrosomal phase
4. Maturation phase

Question 6

What is Kartagener’s syndrome?

Answer 6

Immotile cilia syndrome (cilia lack dynein, the ATPase-containing protein that forms the “arms” on the microtubules in cilia and flagella)

Males with this disorder are sterile and both sexes suffer from chronic sinusitis and bronchitis due to the inability to clear the respiratory passages

Question 7

Endocrine functions of Sertoli cells:

What do they secrete? (6)

Answer 7

ACTIVIN (promotes FSH release) and INHIBIN

FSH acts on seminiferous tubules to increase spermatogenesis AND on interstitial cells to increase their sensitivity to LH

Sertoli cells also secrete ESTROGEN that is thought to have some sort of regulatory role.

ANDROGEN BINDING PROTEIN (ABP) - essential to keep level of testosterone high inside seminiferous tubules

TESTOSTERONE & ANTI-MULLERIAN FACTOR (ensure that Wolffian ducts will develop)

Testosterone production stops before birth and resumes at puberty under influence of pituitary gonadotropins.

Question 8

Describe the duct system

Answer 8

Seminiferous tubules –> Straight tubules –> Rete testis –> Efferent ductules –> Epididymis –> Ductus (vas) deferens

Question 9

What two things occurs to spermatozoa in the epididymis?

Answer 9

1. Acquire motility during passage through epididymis

2. Acquire surface associated proteins that will ultimately be removed in the female reproductive tract

Question 10

What is benign prostatic hyperplasia (BPH)/BP hypertrophy?

Answer 10

Enlargement of the prostate

Hyperplasia - increase in the NUMBER of cells

BPH is linked to DHT which is formed by the action of 5alpha-reductase on testosterone

Question 11

What are the three zones of the prostate?

Answer 11

Transition zone

• Surrounds urethra proximal to ejaculatory duct
• Accounts for 5-10% of glandular tissue of prostate
• Enlargement of this zone –> BPH
• 20% of prostatic cancers

Central zone

• 25% of glandular tissue
• 5% of prostatic cancers

Peripheral zone***

• 70% of glandular tissue
• 70% of prostatic cancers

Question 12

What is capacitation of spermatozoa?

Answer 12

Glycoprotein coat and seminal proteins that overlie the acrosome are removed to enable spermatozoa to fertilize egg

1. Binding of sperm to zone pellucida
2. Acrosome reaction
3. Penetration through zone pellucida
4. Fusion of plasma membranes
5. Sperm nucleus enters egg cytoplasm

Question 13

Genetic Sex Determination: X & Y chromosome

Answer 13

SRY gene that encodes TDF on Y chromosome

AR on X chromosome

Question 14

Describe the process of external genitalia development:

Weeks 4-7:
Week 8-9:
Week 10:

Answer 14

Weeks 4-7: formation of Wolffian and Mullerian ducts

Week 8-9: Testosterone (produced from Leydig cells) acts locally to trigger growth and differentiation of Wolffian duct into rudimentary internal male genitalia (epididymis, vas deferens, seminal vesicles) / AMH (produced from Sertoli cells) causes Mullein ducts to atrophy

Week 10: formation of EXTERNAL male genitalia when testosterone secreted into fetal circulation –> DHT (glans penis, scrotum, prostate gland)