Spermatogenesis

Question 1

What do the testes produce and store?

Answer 1

Testes produce sperm and store it

Question 2

What do the hormones produced by testes do?

Answer 2

These hormones regulate spermatogenesis

Question 3

Where do the testes lie?

Answer 3

Lie in the scrotum outside the body cavity

Question 4

What is the optimum temperature for sperm production?

Answer 4

Optimum temperature for sperm production is 1.5-2.5 degrees below body temperature

Question 5

What is the testes welly done?

Answer 5

Well vascularised and well inervated

Question 6

What is the normal volume of testes

Answer 6

Normal volume of testes approximately 15-25 ml measured by an orchidometer

Question 7

In the testicular structure, where do the tubules lead to?

Answer 7

Tubules lead to an area on one side called the rete

Question 8

In the testicular structure, where does the rete lead to?

Answer 8

Rete leads to the epididymis and vas deferens

Question 9

In the testicular structure, what is the testis 90% made up of?

Answer 9

Testis is 90% seminiferous tubules

Question 10

What is the seminiferous tubules the site of?

Answer 10

Site of spermatogenesis

Question 11

Where are spermatogonia or primary germ cells located?

Answer 11

Spermatogonia or primary germ cells are on the basement membrane

Question 12

What are the walls of the tubules made up of and what do tight junctions between them form?

Answer 12

Walls of the tubules are made up tall columnar endothelial cells called sertoli cells. Tight junctions between these form adluminal compartments

Question 13

What do adluminal compartments allow?

Answer 13

Allow a specific enclosed environment for spermatogenesis which is filled with secretions from srtoli cells

Question 14

What are the spaces between tubules filled with?

Answer 14

Spaces between the tubules are filled with blood and lymphatic vessels, leydig cells and interstitial fluid

Question 15

After how many days is there a new cycle in spermatogenesis

Answer 15

New cycle every 16 days

Question 16

Steps involved in spermatogenesis

Answer 16

1. Mitotic proliferation of spermatogonia
2. Meiosis and development of spermatogonia
3. Spermatogenesis, elongation, loss of cytoplasm, movement of cellular contents

Question 17

What is incomplete in spermatogenesis?

Answer 17

Each cell division from a spermatogonium to a spermatid is incomplete

Question 18

What do the cells in spermatogenesis remain connected with and what does this allow?

Answer 18

The cells remain connected to one another by cytoplasmic bridges forming a syncytium allowing synchronous development

Question 19

What do syncytia at various stages of development throughout seminiferous tubules give?

Answer 19

Syncytia at various stages of development throughout seminiferous tubule give continuous supply

Question 20

Oogonia vs spermatogenesis

Answer 20

• Both oogonia and spermatogonia laid down in foetus
• Both oogonia and spermatogonia begin meiosis to make oocyte and spermatocyte respectively
• You cannot make more oocytes by mitosis whereas you can make more spermatogonia mitotically
• There’s a limited supply of oogonia whereas there’s a lifetime supply of spermatogonia

Question 21

How are steroids produced in testis?

Answer 21

• Leydig cells contain LH receptors and primarily convert cholesterol into androgens. Intra-testicular testosterone levels are 100x those in plasma
• Sertoli cells contain FSH receptors and convert androgens to oestrogen

Question 22

What stimulate sertoli cells and what do they control?

Answer 22

Androgens cross over to testis and stimulate sertoli cell function and thereby control spermatogenesis

Question 23

What does FSH establish compared to androgen?

Answer 23

FSH establishes a quantitatively normal sertoli cell population, whereas androgen initiates and maintain sperm production

Question 24

What do anabolic steroids reduce and what does this eventually lead to?

Answer 24

Anabolic steroids reduce FSH/LH from pituitary due to negative feedback, leading to testicular atrophy

Question 25

How do you get an erection?

Answer 25

By the vasodilation of the corpus cavernosum and partial constriction of the venous return

Question 26

What is an erection under the control of?

Answer 26

Under parasympathetic control

Question 27

ANS in ejaculaiton?

Answer 27

By the ANS causing coordinated smooth muscle contractions of the vas deferens, glands and urethra

Question 28

Sympathetic nervous system in ejaculation?

Answer 28

Sympathetic nervous system controls movement of sperm into epididymis, vas deferens and penile urethra

Question 29

Somatic nervous system in ejaculation?

Answer 29

Somatic nervous system control expulsion of the glandular secretions and evacuations of urethra

Question 30

(Seminal fluid)

What is produced by the bulbourethral gland and what is it known as?

Answer 30

Produces a clear viscous secretion high in salt, known as pre-ejaculate

Question 31

What does the fluid produced by the bulbourethral gland helps?

Answer 31

This fluid helps to lubricate the urethra for some spermatozoa to pass through, neutralising traces of acidic urine

Question 32

(Seminal fluid)
What does the secretions from the seminal vesicles contain and what percentage does the secretion compromise of the ejaculate?

Answer 32

• Contains proteins, enzymes, fructose, mucus, vitamin C and prostaglandins
• Secretions compromise 50-70% of the ejaculate

Question 33

Why does the secretions from the seminal fluid have a great amount of fructose?

Answer 33

High fructose in order to provide an energy source

Question 34

Why does the secretion from the seminal fluid have a high pH?

Answer 34

High pH protects against acidic environment in vagina

Question 35

(Seminal fluid)

What does the prostate secrete and how much does it compose of the seminal fluid?

Answer 35

Secretes milky or white fluid roughly 30% of the seminal fluid

Question 36

What does the secretion from the prostate contain?

Answer 36

Protein content less than 1% and includes proteolytic enzymes, prostatic acid, phosphatase and prostate-specific antigens which are involved in liquefaction

High zinc concentration