Male Reproduction System

Question 1

What is the male reproduction system composed of?

Answer 1

The Male reproduction system is composed of:

• Penis
• Testes
• Genital ducts
• Accessory glands

Question 2

What is the function of the male reproductive system?

Answer 2

The function of the male reproductive system is to produce hormones and sperm

Question 3

Describe the generation of sperm starting with the stem cell and ending with sperm. Denote whether the cell is haploid or diploid

Answer 3

Spermatogonium (2N) -> 
1° Spermatocyte (2N) ->
2° Spermatocyte (N) ->
Spermatid (N) ->
Sperm (N)

Question 4

What temperature does spermatogenesis occur?

Answer 4

• Spermatogenesis occurs only below 37°C.

- The Scrotal Sac maintains a temp of 34°C

Question 5

What are the male gonads and where are they located?

Answer 5

The male gonads are the testes and they are located in the scrotum

Question 6

Describe the structure of the testes

Answer 6

The testes consist of:

• tubules called seminiferous tubules (spermatozoa form here)
• The seminiferous tubules are surrounded by loose connective tissue rich in blood vessels, lymphatics, nerves, and Leydig cells
• Leydig cells produce testosterone

Question 7

What is a Leydig cell?

Answer 7

A Leydig cell surrounds the seminiferous tubules in the testes and produces testosterone

• Testosterone is a steroid derived from cholesterol
• They have a large accumulation of Smooth ER to aid in steroid formation
• They have a well developed golgi apparatus for quick exocytosis of hormones
• Leydig cells also release other androgens like androstenodione and dehydroepiendrosterone

Question 8

What are the seminiferous tubules?

Answer 8

The seminiferous tubules are located in the testes

• Spermatozoa is formed here.
• About 1000 seminiferous tubules are found in the two testes

Question 9

What are the two types of cells found in the seminiferous tubules?

Answer 9

Two types of cells in the seminiferous tubules:

• spermatogenic cells: These generate sperm
• Sertoli cells: These are the “nurse” cells

Question 10

What is a Sertoli Cell?

Answer 10

A Sertoli cell is a special cell type found in the seminiferous epithelium

• These are the “Nurse Cells” of the seminiferous tubules
• They protect, support, and give nourishment to the spermatogenic cells.
• Sertoli cells also do a bit of phagocytosis of cytoplasm eliminated during the production of sperm

Question 11

Describe the roles of hormones in testosterone synthesis and spermatogenesis.

Answer 11

• At puberty, the hypothalamus begins the production of gonadotropin-releasing hormone (GnRH)
• GnRH tells the anterior pituitary gland to secrete LH and FSH
• LH causes the Leydig cells to secrete testosterone
• FSH binds to the Sertoli Cells and aids in spermatogenesis

Question 12

What are the hormonal negative feedback loops of the male reproductive system?

Answer 12

The hormonal negative feedback loops of the male reproductive system are as follows:

• Elevated levels of testosterone in the blood prevents the secretion of for GnRH
• High sperm count causes Sertoli cells to secrete inhibin which inhibits the production of FSH

Question 13

What is the testis?

Answer 13

The testis is one of the testes

- this is where sperm production occurs

Question 14

What is the epididymis?

Answer 14

The epididymis surrounds the testes and is where the maturation of sperm occurs. Sperm attain:

• maturation
• motility
• membrane receptors for the zona pellucida protein (egg membrane protein)
• acrosomal maturation (tip of the sperm where degradative enzymes are found)

Question 15

What is the prostate gland?

Answer 15

The prostate gland:

• Secretes and stores a significant contribution to the seminal fluid
• The fluid is slightly alkaline to help neutralize the acidic environment of the vagina
• Contains smooth muscle that helps expel semen during ejaculation
• Common site for cancer in men over 65

Question 16

Describe prostate cancer and some possible interventions

Answer 16

The prostate is a common site for cancer in men over 65

• A normal product called prostate specific antigen (PSA) is usually elevated in the blood during malignancy. This is a useful test for doctors
• Prostate cancer is usually stimulated to grow more rapidly by testosterone and inhibited by estrogen.
• One possible treatment is to remove the testes (where testosterone is produced) and administer estrogen.

Question 17

What is the vas deferens?

Answer 17

The Vas Deferens is the tube that conveys the sperm from the epididymis to the ejaculatory duct

Question 18

What is the ejaculatory duct?

Answer 18

The ejaculatory duct holds sperm prior to ejaculation and empties it into the urethra.

Question 19

What are the accessory glands?

Answer 19

Accessory glands are glands that add secretions to the semen in addition to what’s secreted by the prostate. They include:

• Bulbourethral glands (Cowper’s glands)
• Seminal Vesicles

Question 20

What are the seminal vesicles?

Answer 20

The seminal vesicles are accessory glands that add secretions to the semen. The secretions make up
about 60% of the semen volume and include:
- amino acids
- proteins
- prostaglandins
- Vitamin C
- fructose (This is the main constituent, it provides the fuel needed for the very motile sperm. NB for the DAT)

Question 21

What is the main constituent of seminal vesicle secretions?

Answer 21

fructose is the main constituent of seminal vesicle secretions, it provides the fuel needed for the very motile sperm. NB for the DAT!

Question 22

What is the Bulbourethral Gland?

Answer 22

The Bulbourethral gland is an accessory gland that secretes:

• thick mucus that aids in neutralizing any acidic urine in the urethra and also aids in lubricating the urethral lining
• This is what pre-cum is. It also can carry some sperm cells, so you can get pregnant even without ejaculation

Question 23

What is the pH of semen when it leaves the urethra?

Answer 23

The pH of semen as it enters the vagina is 7.5

Question 24

Describe the head of a mature sperm cell

Answer 24

The head of a mature sperm cell:

• contains the nucleus
• surrounded on the anterior end by the acrosome
• connects to the neck which contains centrioles

Question 25

What is the acromosome?

Answer 25

The acrosome surrounds the head of a mature sperm on the front of it.

• contains the digestive enzymes (hyaluronidase and acrosin) that will be involved with breaking down the zona pellucida
• derived from the golgi, the acrosome is actually an organelle
• Upon contact with the jelly coat of the egg, exocytosis from the acrosome is triggered releasing the digestive enzymes that drill a hole in the egg.

Question 26

What are the 3 main processes of fertilization?

Answer 26

The three main processes of fertilization are:

• Acrosomal reaction: hydrolytic enzyme release
• Cortical reaction: hardening of jelly coat to prevent potential polyspermy
• Capacitation: Biochemical changes that allow the sperm to swim better

Question 27

What is in the neck of the sperm?

Answer 27

The neck of the sperm contains the sperm centrioles that connect the head to the midpiece.

Question 28

What is in the midpiece of the sperm?

Answer 28

The midpiece of the sperm contains many mitochondria which provide energy for the sperm movement

Question 29

What is the tail of the sperm?

Answer 29

The tail of the sperm is actually a flagellum.

• 9 + 2 microtubule arrangement (Called an Axoneme)
• ATP provided by the midpiece helps fuel dynein, which uses ATPase activity to propel the flagellum

Question 30

What is dynein?

Answer 30

Dynein is a family of motor proteins involved with transport and providing forces during mitosis.
- These proteins are the main motors of sperm motility.

Question 31

How does progesterone in the vagina affect sperm?

Answer 31

Progesterone secreted by the egg into the vagina gives sperm an energy boost to help it swim faster.

• it activates a ca++ channel called CATSPER that somehow increases motility.
• This has recently been discovered and not much is known still

Question 32

Do any animals have internal testes?

Answer 32

YES!

Whales and dolphins internal body temperatures are low enough to have their testes be internal

Question 33

What part of the sperm enters the egg upon fertilization?

Answer 33

The ENTIRE sperm cell from head to tail enter the egg cell.

Question 34

What part of Dad’s DNA is lost?

Answer 34

Dad’s mitochondrial DNA is lost. All the DNA you have in your mitochondria is inherited from your mother.