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HRM > 2 - Spermatogenesis > Flashcards

2 - Spermatogenesis Flashcards

1
Q

What are the accessory glands of the male reproductive tract?

A

Seminal vesicles
Prostate
Bulbo-urethral gland

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2
Q

What muscle maintains testis temperature within a narrow range?

A

Cremaster muscle

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3
Q

What is the general function the testis?

A

Site of sperm production

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4
Q

What is the function of the epididymus?

A

Sperm collection / maturation

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5
Q

What is the function of the vas deferens?

A

Sperm transport

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6
Q

What is the overall function of the accessory glands?

A

Contribute to seminal fluid

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7
Q

What is the function of the urethra?

A

Transport

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8
Q

What is the path of a sperm through its development along the male reproductive tract (in the testicle)?

A

Seminiferous tubules
Rete testis
Ductus efferentes
Epididymus

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9
Q

What do sperm first acquire motility?

A

Epididymus

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10
Q

What hormone enables sperm motility within the epididymus?

A

DHT

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11
Q

What enzyme mediates the conversion of DHT from testosterone?

A

5alpha-reductase

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12
Q

Why is the sperm fraction concentrated within the epididymus?

A

Capable of reabsorbing fluid within the epididymus.

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13
Q

What proteins are secreted within the epididymus to arrest sperm function?

A

Proteins that bind to sperm head and inhibit EARLY capacitation.

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14
Q

What is the function of Leydig cells?

Where are they found?

A

Leydig cells convert cholesterol into testosterone.

Around the seminiferous tubules.

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15
Q

Where is testosterone converted into DHT?

A

Sertoli cells

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16
Q

What 2 cell populations make up the seminiferous epithelium?

A

Sertoli cells

Spermatogenic lineage cells (sperm precursors)

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17
Q

Outside the seminiferous tubules, what two cells are found?

A

1) Leydig cells

2) Myoid cells

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18
Q

What are the 2 functions of myoid cells?

A

Structural integrity.

Movement of sperm.

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19
Q

What are the 2 important compartments of the seminiferous tubules?

A

1) Adluminal compartment

2) Basal compartment

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20
Q

What characteristics / functions of both the adluminal / basal compartments are different?

A

Adluminal membrane = diffusional barrier.

Basal layer = barrier to blood supply.

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21
Q

Why is the structural integrity of the basal layer so important?

A

Stops contact of sperm and blood.

Inhibits possibility of big auto-immune reaction.

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22
Q

What is the name of an immune reaction if sperm were to enter the blood stream?

A

Autoimmune orchitis.

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23
Q

How many mature sperm can a single spermatogonium make?

A

64

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24
Q

In the progression of 1 spermatogonium, how many rounds of mitosis occur?

What is this process termed as?

A

4

Clonal expansion

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25
Q

Following 4 rounds of mitosis, what process then occurs?

At what stage of sperm development?

A

Meiosis I and II

Spermatocyte

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26
Q

What are the two distinct phases of spermatogenesis?

A

Spermatocytogenesis

Spermiogenesis

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27
Q

Following meiosis, what stage of sperm production is reached?

A

Spermatid

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28
Q

In the context of genetic information, how is the spermatid different from its precursor?

A

Haploid

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29
Q

What is the final stage of spermatogenesis?

A

Spermiogenesis

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30
Q

What is spermiogenesis?

A

Cytoplasmic remodelling of the sperm.

Final stage, seeing the maturation of spermatids into spermatozoa.

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31
Q

In spermiogenesis, what do golgi eventually form?

A

Lysosomal granules which coalesce to form the acrosome.

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32
Q

What do the proximal centrioles form in spermiogenesis?

A

Neck of sperm

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33
Q

What do the distal centrioles form in spermiogenesis?

A

Flagellum

34
Q

What do the mitochondria form in spermiogenesis?

A

Flagellar motor

35
Q

What is the function of cytoplasmic droplets?

A

Remove excess cytoplasm

36
Q

What is the process called when sperm are released into seminiferous tubule lumen?

A

Spermiation

37
Q

What enzymes are contained within the acrosome?

A

Hyaluronidases

38
Q

What cells do hyaluronidase enzymes mainly digest?

A

Cumulus cells

39
Q

How is DNA packed within the head of the sperm?

Why is this?

A

Histone proteins are exchanged for smaller, protanine proteins.

Too large for sperm head space.

40
Q

What is the DNA within the head of the sperm known as?

A

Heterochromatin

tightly packaged DNA

41
Q

What gene is really important in ensuring the integrity of sperm head structure?

A

DPY19L2

Gene that codes for a protein which anchors the nuclear membrane to the acrosomal cap.

42
Q

How are mitochondria arranged, relative to the flagella?

A

Arranged helicoidally around the flagellum.

43
Q

What arrangement of microtubules occurs in the sperm mid-piece?

A

9*2 +2 arrangement.

9 doublets in a circle with a single central doublet.

44
Q

What are the 3 regions of the mature sperm?

A

Head
Midpiece
Principle piece

45
Q

What region of the sperm contains the mitochondria?

A

Midpiece

46
Q

Microtubules are associated with an important protein. What is it?

What is its function?

A

Dynein.

ATP-ase.

Provides microtubules with energy by hydrolysing ATP.

47
Q

How many spermatocytes do spermatogonium give rise to?

A

16

48
Q

How many spermatozoa to do primary spermatocytes give rise to?

A

4

49
Q

How many spermatagonia start the process of sperm development EACH DAY?

A

3,000,000

50
Q

How many die each day?

A

Half of 3 million

51
Q

How many sperm are left each day?

A

10^8.

52
Q

How long does sperm formation take?

A

70 days

53
Q

How many days does it take sperm to reach the ejaculatory ducts from being formed?

A

14 days.

54
Q

What 4 components make up the normal sperm fraction?

A

1) Epididymus + vas deferens
2) Prostate
3) Seminal vesicle
4) Bulbourethral gland

55
Q

What percentage does the epididymus + vas deferens contribute to the ejaculate volume?

A

5%

sperm-rich

56
Q

What % does the prostate contribute to the ejaculate volume?

A

13-33%

57
Q

What % does the seminal vesicle contribute to the ejaculate volume?

What two components are important in this secretion?

A

45-80%

Prostaglandins
Fructose (ENERGY)

58
Q

What % does the bulbourethral gland contribute to the ejaculate volume?

A

5%

59
Q

What pattern of sperm motility occurs when semen meets cervical mucus?

A

Arrange themselves into columns (groups of sperm) known as phalanges.

60
Q

What hormonal changes in the female mediate the viscosity of cervical mucus?

A

Estrogen predominating results in mucin production, making the mucus less viscous - arranges proteins into channels.

Progesterone then inhibits estrogen production and mucus becomes impenetrable.

61
Q

What % of males are infertile?

A

5-7%

62
Q

What fraction of couples are infertile?

A

1/6

63
Q

What are some of the major causes of male infertility?

A

Sperm production (i.e. low numbers, poor quality)

64
Q

What fraction of infertile couples are thought to to be solely due to male issues?

A

Over 1/3

65
Q

Give examples of infertility causes:

A

Varicocele
Infection
Ejaculatory problems
Hormone imbalance

Lifestyle

66
Q

What does the term ‘Globozoospermia’ refer to ?

A

Production of round-headed sperm.

67
Q

What is the pathophysiology of globozoospermia?

A

Undeveloped acrosome cap.

68
Q

The mutation of which gene can result in globozoospermia?

A

DYP19L2

69
Q

What is the inheritance pattern in a mutated DYP19L2 gene?

A

Autosomal recessive

70
Q

What is a general overview of the procedure that occurs in Intracytoplasmic Sperm injection (ICSI) ?

A

Similar procedure to IVF where both egg and sperm are removed from respective partners.

ICSI artificially implants sperm into oocyte in cases where sperm are incapable of doing so.

71
Q

What are 6 clinical findings shown through ICSI in rodent studies?

A

1) Decreased rate of preimplantation embryonic development.
2) Decreased offspring number
3) Higher post-natal weight grain
4) Increased tumour formation rate
5) Increased anxiety in female offspring
6) Premature ageing

72
Q

What is the principle behind germline stem cell research for spermatogenesis?

A

Spermatogonial stem cells can be isolated from testis tissue.

Cryopreserved.

Transplanted back into recipient when reached sexual maturity.

Potentially become capable of sperm production.

73
Q

What clinical condition might germline stem cell therapy be useful?

A

In children with leukaemia - require high dose chemotherapy / irradiation which can render them infertile.

74
Q

Why might constant economic growth be at the root of poor sperm quality?

(Author?)

A

Low demand for big families.

Almost no selective pressure.

Selecting for sperm that aren’t optimal.

(Lutz W,. 2006)

75
Q

Name one example of a genetic disease that, without modern reproductive techniques, would render an individual infertile, but would now not?

A

Klinefelter’s syndrome.

Would be 47XXY (Klinefelter’s), traditionally thought to be infertile.

However, testis biospy or recovery from ejaculate would find samples of 23X 23Y sperm. HOWEVER, might HIGHER RATES OF ANEUPLOIDY.

76
Q

What is an important difference often found amongst infertile sperm compared to fertile samples in the context of resistance to oxidative stress?

A

Naturally, with very small cytoplasmic space, sperm are predisposed to oxidative stress as a result of having few anti-oxidative enzymes.

Also a large number of oxidative attack sites in light of many POLYUNSATURATED fatty acids.

77
Q

What is the differences, in the context of oxidative stress, between normal DNA and sperm DNA (heterochromatin)?

A

Heterochromatin is much more resistant to oxidative attack - protamines?

However, heterochromatin is much less capable of DNA repair.

78
Q

There are only two known heterochromatin repair enzymes. What are they?

A

OGG1

APE1

79
Q

What is commonly found, in the context of oxidative stress, in sub-fertile individuals?

A

Oxidative attack as a result of relative lack of DNA repair capital.

80
Q

Although men can continue to make sperm beyond 80, what factor of oxidative damage is true for males over 35 years old, compared to younger counterparts?

A

3x the amount of oxidative damage.

HRM (9 decks)

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