Reproductive System I (Male)

Question 1

Is the reproductive system necessary to individual life?

Answer 1

No.
However, it is necessary for the continuation of a species.

Question 2

What are the male reproductive structures?

Answer 2

Gonads, ducts, accessory glands, external genitalia.

Question 3

What are gonads?

Answer 3

Organs that produce gametes and hormones

Question 4

What do ducts do?

Answer 4

Receive and transport gametes.

Question 5

What do reproductive accessory organs do?

Answer 5

Secrete fluid into ducts.

Question 6

What is the function and location of the male gonads?

Answer 6

Testis: produce sperm.
Suspended in the scrotum. Part of the external genitalia.

Question 7

What is the path traveled by sperm?

Answer 7

Generated in the testis, travel into the epididymis, then into the ductus/vas deferens, it then combined with the secretions of accessory organs and enters the ejaculatory duct, which joins with the urethra.

Question 8

What are the three accessory glands? Where are they?

Answer 8

Seminal gland: releases secretions (70% of ejaculated semen) into the ejaculatory duct. Located between the bladder and rectum.

Prostate gland: releases 25% of the ejaculate. Inferior to the bladder and seminal gland.

Bulbourethral gland: secretes lubricant for the penis. Inferior to the prostate gland.

Question 9

What are spermatic cords?

Answer 9

Bundles of nerves, ducts (vas deferens), and blood vessels suspending the testis in the scrotal sac from the abdomen.
Cords begin at the inguinal canal.

Question 10

What causes an inguinal hernia?

Answer 10

Visceral structures (ex. small intestine) protrudes into the inguinal canal (passageway through abdominal muscle).
Likely due to weakness or increased stress of abdominal muscles.
Treated with surgery.

Question 11

Why are the testis housed in the scrotal sac?

Answer 11

Temperature regulation.

Normal sperm development requires a temperature around 1*C lower than normal body temperature.

Question 12

How is temperature regulated in the scrotum?

Answer 12

Regulated with the cremaster and dartos muscles.

Body temp increase: muscles relax, moving the testis farther away to cool down.

Body temp drop: muscles contract to bring testis closer to the body for warmth.

Question 13

What are seminiferous tubules?

Answer 13

Location of sperm production. Slender, tightly coiled tubules in the lobules of the testis. Separated by CT.

Question 14

Describe the stages of spermatogenesis in a seminiferous tubule.

Answer 14

1. Spermtogonium undergoes mitosis to form primary spermatocytes.
2. One primary spermatocyte will form two secondary spermatocytes each after undergoing meiosis I and will move toward the lumen. The other primary spermatocyte remains in reserve.
3. After meiosis II, Spermatids (from the secondary spermatocyte) will begin spermiogenesis (physical maturation), creating sperm which will leave through the lumen.

Explanation available around 38 minutes into 11 AM lecture on 11/21.

Question 15

What are nurse/Sertoli cells? What do they do?

Answer 15

Large cells extending from the basement membrane to the lumen.

Form the pocket where sperm develops.
Synthesize anti-mullerian hormone (AMH), inhibin, androgen binding protein (ABP), etc.

Question 16

What are the interstitial endocrine / Leydig cells?

Answer 16

Produce hormones like testosterone.

Found below the basement membrane in the CT.

Question 17

Describe the blood-testis barrier.

Answer 17

Isolates seminiferous tubules from general circulation. Formed by tight junctions so sperm does not come into contact with immune cells.

Question 18

What are the key differences between mitosis and meiosis?

Answer 18

Mitosis: Parent cell forms two identical, diploid daughter cells.
Fewer steps of division. 46 C.

Meiosis: Parent cell forms four unique, haploid daughter cells.
More steps of division. 23 C.

Question 19

What are the stages of mitosis?

Answer 19

1. Prophase
2. Metaphase
3. Anaphase
4. Telophase and cytokinesis

Question 20

What are the stages of meiosis?

Answer 20

1. Prophase I
2. Metaphase I
3. Anaphase I
4. Telophase I
5. Metaphase II
6. Anaphase II
7. Telophase II and cytokinesis

Question 21

Be able to describe the stages of mitosis and meiosis.

Answer 21

Explanation and depiction found around 30 minutes into 11 AM lecture on 11/21.

Question 22

When does spermatogenesis begin in males? End?

Answer 22

Puberty to around 70 years old.

Question 23

How long does spermatogenesis take?

Answer 23

Around 64 days.

Question 24

Why can males reproduce longer than females?

Answer 24

When spermatogonium undergo mitosis, only one daughter cell moves toward the lumen and the other stays in reserve, ensuring one of the cells is always available. In females, there is no ‘reserve’ of this kind.

Question 25

What is spermiogenesis? How does it happen?

Answer 25

Differentiation of spermatid into a sperm.

An acrosomal vesicle (contains enzymes for fertilization) moves toward the nucleus. Much of the cytoplasm is shed. Results in sperm structure (head and tail).
Takes around 24 days.

Question 26

What method(s) can sperm use to make ATP?

Answer 26

Both aerobic and anaerobic.

Question 27

What hormones are required for the development of the male phenotype?

Answer 27

AMH, testosterone

Question 28

Describe the role of nurse cells in sperm development

Answer 28

Nurse cells maintain the blood-testis barrier, protecting sperm from immune cells.
Secrete ABP, keeping testosterone high, which stimulates spermatogenesis.
Supports spermiogenesis by providing nutrients and chemical stimuli. Phagocytizes (“eats”) the cytoplasm being shed.

Question 29

What is the structure and function of the epididymis?

Answer 29

Coiled tube at the start of male reproductive tract.
Head: sperm is produced in seminiferous tubules.
Body: posterior surface of each testis.
Tail: Inferior region of testis, then ascends into vas deferens. Primary site of sperm storage.

Primary function: Site of sperm storage and maturation. Recycles damaged sperm.

Question 30

What happens in capacitation?

Answer 30

1. Sperm becomes motile when mixed with the secretions of the seminal gland.
2. Sperm becomes capable of feralization when exposed to the female reproductive tract.

Question 31

Describe the secretions of the seminal gland.

Answer 31

Similar osmotic concentration to blood plasma, but contains fructose (nutrient), prostaglandins (smooth muscle contractions for mobility), fibrinogen (temporarily clots vagina). Slightly alkaline composition to neutralize prostate secretions and vaginal secretions.
Makes the sperm motile.

Question 32

Describe the secretions of the prostate gland.

Answer 32

Slightly acidic. Has an enzyme preventing sperm coagulation by dissolving the clot formed by fibrinogen.

Question 33

What is prostitis?

Answer 33

Inflammation of the prostate gland, which the urethra passes through. Results in difficulty urinating.

Question 34

What is benign hypertrophic hyperplasia?

Answer 34

Hypertrophy of the prostate, making it difficult to urinate. Affects men over 50yo.

Question 35

Describe the secretions of the bulbourethral gland.

Answer 35

Alkaline mucus secretion to neutralize urinary acids in the urethra. Helps to lubricate the tip of the penis.

Question 36

What anterior pituitary glands play a role in reproductive function?

Answer 36

F - follicle stimulating hormone (FSH)
L - luteinizing hormone (LH)
A - adrenocorticotropic hormone (ACTH)
P - Prolactin

Relevant for males: FSH, LH

Question 37

LEARN THE FLOW CHART FOR HORMONAL REGULATION OF MALE REPRODUCTIVE SYSTEM!

Answer 37

Explained and depicted 13 minutes into 11 AM lecture on 11/22.

Question 38

Why can taking testosterone lead to male infertility?

Answer 38

Testosterone has a negative feedback effect by directly inhibiting GNRH release. If taking testosterone injections, testosterone will always be high and actively inhibiting GNRH. This causes FSH and LH levels to decrease, which affects spermatogenesis in nurse cells.