Histology -- Spermatogenesis

Question 1

Define spermatogenesis

Answer 1

An elaborate process of cell differentiation starting with non-differentiated spermatogonial stem cell and terminating with a fully differentiated highly specialized motile cell called spermatozoa

Question 2

Location of the formation of spermatozoa

Answer 2

Seminiferous epithelium

Question 3

2 populations of cells composing the seminiferous epithelium

Answer 3

Somatic Sertoli cells

Spermatogenic cells

Question 4

Fate of spermatogonia

Answer 4

Division and differentiation into spermatocytes

Question 5

Fate of spermatocytes

Answer 5

Undergo meiosis to originate spermatids

Question 6

3 phases of spermatogenesis

Answer 6

1. Spermatogonial phase (proliferation, renewal and differentiation of spermatogonia)
2. Spermatocyte phase (meiosis)
3. Spermatid phase (spermiogenesis)

Question 7

3 types of spermatogonia and what differentiates them from each other

Answer 7

• Type Ad (dark; less active)
• Type Ap (pale; true stem cells)
• Type B (differentiated)

Question 8

Amount of DNA in primary spermatocytes and why

Answer 8

4n (44 autosomes and an X and a Y chromosome each having two chromatin strands or chromatids) since spermatocytes replicate their DNA shortly after they form

Question 9

4 stages of prophase of the first meiotic division of spermaocytes

Answer 9

• Preleptotene
• Leptotene
• Zygotene-Pachytene
• Diplotene

Question 10

Describe the preleptotene and leptotene phases of spermatocyte division

Answer 10

Chromatin condenes into visible chromosomes

Question 11

Describe the Zygotene-Pachytene of spermatocyte division

Answer 11

Homologous chromosomes paired

Question 12

Describe the diplotene stage of spermatocyte division

Answer 12

Pairs of homologous chromosomes called tetrads (because they consist of 4 chromatids) exchange genetic material by crossing over

Question 13

Describe what occurs afer prophase of spermatocyte division

Answer 13

Primary spermatocytes divide and the tetrads separate to become diads in the daughter cells

Question 14

Amount of DNA in secondary spermatocytes

Answer 14

2n DNA (22 autosomes and an X or a Y chromosome [haploid])

Question 15

Describe what occurs during the metaphase of the second division of spermatocytes

Answer 15

Sister chromatids separate into two haploid round spermatids

Question 16

Amount of DNA in round spermatids

Answer 16

1n amount of DNA

Question 17

4 phases of spermiogenesis

Answer 17

• Golgi phase
• Cap phase
• Acrosome phase
• Maturation phase

Question 18

Describe the Golgi phase of spermiogenesis

Answer 18

The Golgi apparatus forms a proacrosomic granule within an acrosomic vesicle. Centrioles start forming the axonese (tail)

Question 19

Describe the cap phase of spermiogenesis

Answer 19

The acrosomal vesicle spreads to cover the anterior half of the nucleus.

Question 20

Describe the acrosome phase of spermiogenesis

Answer 20

The head of the spermatid is oriented towards the basement membrane. The machete of microtubules forms and the Golgi apparatus migrates posteriorly.

Question 21

Describe the maturation phase of spermiogenesis (4 events)

Answer 21

1. Spermatid elongates
2. Chromatin condenses
3. Mitochondria migrate and form the mid piece of the tail (NOTE: Primary piece has no mitochondria)
4. A residual body (surplus of cytoplasm) is formed and eliminated

Question 22

Duration of spermatogenesis in a man

Answer 22

Fixed and constant at 60 days

Question 23

Frequency at which stem cells enter spermatogenesis in a man

Answer 23

Regular intervals of 16 days

Question 24

Describe how stem cells enter spermatogenesis

Answer 24

In groups, the members of which are connected by open intercellular bridges, which also connect the daughter cells until the end of spermatogenesis

Question 25

What structure contains the hydrolytic enzymes necessary for he fertilization of the ovum?

Answer 25

Acrosomic cap structure

Question 26

Define one generation of germinal cells

Answer 26

One group of cells at one stage of development

Question 27

Number of generations of germinal cells seen in the epithelium of the seminiferous tubules

Answer 27

4 - 5

Question 28

Cause of immotile cilia syndrome in men

Answer 28

Mutations in the dynein gene and in other genes encoding proteins required for flagellar and ciliar motility

Question 29

Associated conditions to immotile cilia syndrome

Answer 29

Chronic respiratory infections (impaired motility of the cilia of the respiratory epithelium)

Question 30

Potential use for stem cell transplantation regarding male testes

Answer 30

Useful in testicular cancer of young individuals (use for fertilization post-radiotherapy, which kills sperm cells)

Question 31

Situation in which in vitro fertilization is useful

Answer 31

Obstructive azoospermia

Question 32

Define ICSI

Answer 32

Intracytoplasmic sperm injection into oocytes

Question 33

Define ROSNI

Answer 33

Round spermatid nuclear injection into oocytes

Question 34

Define ROSI

Answer 34

Round spermatid injection into oocytes