4.0 Male Gametogenesis Flashcards

1
Q

Define fecundity

A

<b>The potential for reproduction</b><br></br>- Gamete production, fertilization and carrying pregnancy to term

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2
Q

Define fertility

A

<b>Measure of reproduction</b><br></br>Number of children born per person, couple or population

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3
Q

Define fertility rate

A

<b>Number of births per time period per person, couple or population</b>

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4
Q

What factors affect fertility in women?

A

1) Age (puberty → menopause)<br></br>2) Choice (abstinence)<br></br>3) Fecundity is episodic (monthly)<br></br>4) Sub-fertility<br></br>5) Social convention<br></br>6) Access to A.R.T

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5
Q

What factors affect fertility in men?

A

1) Age (post-puberty)<br></br>2) Choice (abstinence)<br></br>3) Social convention<br></br>4) Sub fertility<br></br>5) Fecundity is continuous<br></br>6) Access to A.R.T

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6
Q

What causes cessation of fecundity in women?

A

<b>Menopause</b><br></br>Usually ~40yrs (2% early menopause - 20yr+)<br></br>Ovarian decline/failure → <b>secondary amenorrhoea</b>

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7
Q

What causes menopause?

A

<b>Ovarian decline and failure</b><br></br>1) Fewer oocytes of lower quality → ↑ chromosomal anomalies<br></br>2) Follicular decline → hormonal changes → secondary amenorrhoea

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8
Q

What causes male cessation of fecundity?

A

1) Loss of libido<br></br>2) Erectile dysfunction<br></br>3) Vascular pathology

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9
Q

On average how many years earlier do girls hit puberty?

A

2 years earlier

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10
Q

What are the cells in the male gonad?

A

1) Germ cells (primordial germ cells, spermatogonia, spermatocytes)<br></br>2) Spermatozoa<br></br>3) Sertoli cells<br></br>4) Leydig cells

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11
Q

What are the cells in the female gonad?

A

1) Germ cells (oocyte)<br></br>2) Ova<br></br>3) Granulosa cells<br></br>4) Thecal cells

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12
Q

Compare the germ cells in the testis and ovary:

A

“<div><img></img></div>”

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13
Q

At what stage are cells arrested in the <b>dictyate stage</b>?

A

Meiotic prophase

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14
Q

Compare the generation of gametes in testis and ovaries:

A

“<div><img></img></div>”

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15
Q

How many degrees cooler are the testes compared to body temp?

A

4-7 degrees

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16
Q

What contributes to the testes being cooler than body temp?

A

1) Position (in scrotum outside body)<br></br>2) Circulation (pampiniform plexus)<br></br>3) Divided into compartments

17
Q

What forms the blood-testis barrier?

A

<b>Sertoli cells</b><br></br>- Junctional complexes between sertoli cells = main barrier to diffusion

18
Q

What is the purpose of the blood-testis barrier?

A

Prevents penetration of tubular wall<br></br>Prevents penetration of basal component and adluminal compartment

19
Q

What are the consequences of breakdown of blood/testis barrier?

A

1) Autoallergic orchitis<br></br>2) Alterations in tubular microenvironment

20
Q

What cells are located within the seminiferous tubules in the male gonads?

A

1) <b>Spermatogonia</b> (mitotic)<br></br>2) <b>Spermatocyte</b> (meiotic)<br></br>3) <b>Spermatid</b> (haploid)<br></br>4) <b>Sertoli cells</b> (produce inhibin and testicular fluid)

21
Q

What cells are located outside tubules (interstitially) in the male gonads?

A

1) <b>Leydig cells</b> - 4-10mg androgen daily<br></br>2) <b>Blood vessels and lymphatics</b>

22
Q

What are the stages of spermatogenesis:

A

<b>1) Mitosis</b><br></br>- 5 to 7 divisions<br></br>- Mitotic activity of spermatogoni<br></br><b>2) Meiosis</b><br></br>- Occurs in spermatocytes<br></br>- They move more luminally as they divide<br></br><br></br><b>3) Maturation (spermiogenesis)</b><br></br>- Post-meotic <b>spermatids</b> change phenotypes<br></br>- round spermatid → elongated spermatid → spermatozoa

23
Q

What is spermiation?

A

Release of spermatozoa into testicular fluid

24
Q

What cell regulates all stages of spermatogenesis?

A

Sertoli cells

25
How long does it take from stem cell to spermatozoa?
64 days
26
What is the interval between groups of cells initiating sperm development?
16 days

Locally coordinated but different localities are not synced → continuous output of sperm
27
What cells secrete androgens?
Leydig cells
28
Functions of androgens?
1. Masculinise soma
2. Influence brain and behaviour
3. Stimulate accessory sex gland growth and secretion in men (seminal vesicle, prostate, epididymis)
4. Secondary sex body hair patterns in both men and women
3. Exert anabolic and myotrophic effects to affect body shape
29
What are the three gonadotrophins needed for testicular function?
1) LH
2) FSH
3) Inhibin
30
Structure of LH:
Glycoprotein with 2 peptide chains

α chain
Common with FSH - 92 amino acid + 2 carb groups
β chain
Unique - 122 amino acids + 2 carb groups
31
Where is LH secreted from and what cell does it act on?
Secreted from ant. pituitary
Acts on Leydig cells
32
Structure of FSH:
Glycoprotein with 2 peptide chains

α chain
Common with LH - 92 amino acid + 2 carb groups
β chain
Unique - 111 amino acids + 6 carb groups
33
Where is FSH secreted from and what cell does it act on?
Secreted from ant. pituitary
Acts on Sertoli cells
34
Structure of inhibin:
α chain + β chain joined by disulphide bridge
35
Where is Inhibin secreted from and where is it secreted into?
Secreted by Sertoli cells (under influence of FSH)

75% → testicular fluid
25% → testicular lymph