Meiosis/Mitosis and Spermatogenesis

Question 1

What will occur as a result of non-descent of the testes?

Answer 1

Viable sperm will not be produced.
Testosterone production will cease

Question 2

The bulbourethral glands drain into the:

Answer 2

spongy urethra

Question 3

What is spermatogenesis?

Answer 3

the process of sperm (gamete) production

Question 4

Where does spermatogenesis occur?

Answer 4

seminiferous tubules

Question 5

How do spermotogenic cells give rise to sperm?

Answer 5

Mitosis

Question 6

During Mitosis how many daughter cells are created?

Answer 6

2

Question 7

What is the purpose of Type A daughter cell?

Answer 7

remain at the basal lamina and maintain the pool of dividing spermatogonia
(A = always ready to begin new generations of gametes)

Question 8

What is the purpose of Type B daughter cell?

Answer 8

Become a primary spermatocyte destined to produce 4 sperm

Question 9

What is the name of secondary spermatocytes daughter cells

Answer 9

Spermatids

Question 10

During Meiosis I spermocytes form two smaller haploid cells called

Answer 10

secondary spermatocytes

Question 11

During Meiosis II spermatids turn off nearly all their genes and compact the DNA.
True or False

Answer 11

True

Question 12

During Spermiogenesis each spermatid has the correct number of chormosomes for fertilizations but is nonmotile. What must it do to become motile?

Answer 12

it elongates, sheds its excess cytoplasmic baggage and forms a tail

Question 13

What is the function of a hydrolytic enzyme found in the head of the sperm

Answer 13

enables the sperm to penetrate the egg

Question 14

The midpiece of sperm contains the:

Answer 14

Mitochondria

Question 15

What is the purpose of the mitochondria in the midpiece of the sperm?

Answer 15

provide metabolic energy (ATP) needed for the whiplike movements of the tail

Question 16

How long is the process of spermatogenesis?

Answer 16

64-72 days

Question 18

How can sperm in the lumen make its way to the testes?

Answer 18

pressure of testicular fluid

Question 19

What is the purpose of the blood testi barrier?

Answer 19

prevents membrane antigens of differentiating sperm from escaping through the basal lamina into the blood

Question 20

Why would differentiating sperm entering the blood stream be a bad thing?

Answer 20

They could activate the immune system

Question 21

Which cell is responsible for forming the blood-testi barrier?

Answer 21

Sustentocytes

Question 22

What other roles do sustenocytes play?

Answer 22

1. provide nutrients to dividing cells
2. Move spermatocytes and spermatids along the lumen
3. secrete testicular fluid that provides the transport medium for sperm in the lumen
4. phagocytize faulty spermatoegnic cells
5. Produce androgen-binding protein and keep levels of testosterone high

Question 23

What is the role of the hormone inhibin

Answer 23

inhibit FSH release from the anterior pituitary and therefore inhibits spermatogenesis

Question 24

Levels of inhibin are propportional to sperm count. the ____ the level of sperm the higher the level of inhibin

Answer 24

higher

Question 25

Describe the major structural and functional regions of a sperm.

Answer 25

The sperm head is the compacted DNA-containing nucleus. The acrosome that caps the head is a lysosome-like sac of enzymes. The midpiece contains the energy-producing mitochondria. The tail, a flagellum, is the propulsive structure.

Question 26

Which cells surround and nourish developing sperm?

Answer 26

Sustentocytes

Question 27

Why is the HPG axis under the CNS control?

Answer 27

Because input from other brain areas also influence the hypothalamus

Question 28

What occurs in the absence of GnRH and gonadtropins?

Answer 28

The tests atrophy and sperm and testosterone production cease

Question 29

Development of the male reproductive structures depend on

Answer 29

prenatal secretion of testosterone

Question 30

Explain the levels of testoterone and gonadtropin in a male infant a few months before birth

Answer 30

Nearly 2/3 of those of an adult male

Question 31

What occurs to the testosterone and gonadtropin levels after birth?

Answer 31

after a brief rise in early infancy the blood levels of these hormones will recede and remain low throughout childhood. At puberty higher levels of testosterone are required to suppress release and GnRH.

Question 32

Testosterone is synthesized from

Answer 32

cholesterol

Question 33

In the prostate testosterone is converted to

Answer 33

dihydrotestosterine (DHT)

Question 34

In the brain, bone and fat testosterone is converted to

Answer 34

estradiol

Question 35

What are male secondary sex characteristics?

Answer 35

features produced by nonreproductive organs by androgens that develop at puberty

Question 36

What are some secondary sex hormones?

Answer 36

appearance of pubic hair, axillary and facial enhances hair growth on the chest deepening of voice increased size and density of bones increase size and mass of skeletal mucles

Question 37

What are the somatic effects of testosterone?

Answer 37

Increased size and denisty of bones Increased size and mass of skeletal muscles (remember soma = body)

Question 38

What is another androgen released by the adrenal glands?

Answer 38

gonadocorticosteroid

Question 39

Are gonadocorticosteroid sufficient to support normal testosterone-mediated functions?

Answer 39

No - they are released in relatively small amounts by the adrena glands

Question 40

Spermatogenesis is self perpetuating. Explain what this means

Answer 40

The process is able to continue indefintely on its own as long as the conditions are right

Question 41

As men get older they stop producing sperm. True or False

Answer 41

False Spermatogonia stay behind and keep dividing ensuring that sperm production doesnt run out and will keep going throughout a mans life. However, it will slow down with age

Question 42

What is the starting point of meiotic division

Answer 42

Primary Spermatocyte

Question 43

During Secondary Spermatocyte how many copies of each chromosome are provided

Answer 43

2 copies of each of 23 chormosomes

Question 44

The sperm will determine the sex of a fetus at which stage of meiosis?

Answer 44

during secondary spermatocyte. 2 copies of each chromosome are joined together. It is at this stage that the sperm will have XX chromosome (female) or XX chromosome (male)

Question 45

Why is it that the sperm will determine the sex of a fetus

Answer 45

because sperm will carry either an XX chormosome or and XY chromosome, while the egg will only carry XX chromosomes

Question 46

It is important that Leydig cells are vascularized for:

Answer 46

efficient hormone transfer Nutrient and cholesterol supply

Question 47

Why is important that leydig cells have easy access cholesterol

Answer 47

They need cholesterol to make testosterone

Question 48

how many days will sperm spend in the epididymis?

Answer 48

20

Question 49

How do Seminal Vesicles contribute to semen

Answer 49

Secrete a viscous yellow fluid rich in fructose and protoglandins

Question 50

Why does semen need fructose?

Answer 50

energy to swim through the female reproductive tract

Question 51

Why does semen require prostaglandins?

Answer 51

stimulate muscle contractions in females reproductive tract to help move sperm toward the egg help loosen cervical mucus

Question 52

What is the source and role of GnRH?

Answer 52

GnRH is released by the hypothatalmus and it stimulates the anterior pituitary

Question 53

What is the source of FSH and LH and what are their roles

Answer 53

FSH and LH are released by the anterior pituitary FSH indirectly stimulates spermatogenesis LH stimulates insterstital endocrine cells to secrete testosterone

Question 54

LH stimulates interstital cells to secrete Testosterone. What is the role of testosterone

Answer 54

1. necessary for sperm production 2. acts on other body sites to stimulate maturation of sex organs 3. development and maintenance of secondar sex characteristics

Question 55

Explain the negative feedback by testosterone

Answer 55

Inhibits FSH and LH release from the anterior pituitary inhibts GnRH released from the hypothalamus

Question 56

Sertoli cells release inhibin which:

Answer 56

feeds back to the anterior pituitary decreasing FSH release