4.0 Male Gametogenesis Flashcards Preview

MedST IB: Human Reproduction (HR) > 4.0 Male Gametogenesis > Flashcards

Flashcards in 4.0 Male Gametogenesis Deck (35)
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1

Define fecundity

The potential for reproduction
- Gamete production, fertilization and carrying pregnancy to term

2

Define fertility

Measure of reproduction
Number of children born per person, couple or population

3

Define fertility rate

Number of births per time period per person, couple or population

4

What factors affect fertility in women?

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

5

What factors affect fertility in men?

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

6

What causes cessation of fecundity in women?

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

7

What causes menopause?

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

8

What causes male cessation of fecundity?

1) Loss of libido
2) Erectile dysfunction
3) Vascular pathology

9

On average how many years earlier do girls hit puberty?

2 years earlier

10

What are the cells in the male gonad?

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

11

What are the cells in the female gonad?

1) Germ cells (oocyte)
2) Ova
3) Granulosa cells
4) Thecal cells

12

Compare the germ cells in the testis and ovary:

"
"

13

At what stage are cells arrested in the dictyate stage?

Meiotic prophase

14

Compare the generation of gametes in testis and ovaries:

"
"

15

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

4-7 degrees

16

What contributes to the testes being cooler than body temp?

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

17

What forms the blood-testis barrier?

Sertoli cells
- Junctional complexes between sertoli cells = main barrier to diffusion

18

What is the purpose of the blood-testis barrier?

Prevents penetration of tubular wall
Prevents penetration of basal component and adluminal compartment

19

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

1) Autoallergic orchitis
2) Alterations in tubular microenvironment

20

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

1) Spermatogonia (mitotic)
2) Spermatocyte (meiotic)
3) Spermatid (haploid)
4) Sertoli cells (produce inhibin and testicular fluid)

21

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

1) Leydig cells - 4-10mg androgen daily
2) Blood vessels and lymphatics

22

What are the stages of spermatogenesis:

1) Mitosis
- 5 to 7 divisions
- Mitotic activity of spermatogoni
2) Meiosis
- Occurs in spermatocytes
- They move more luminally as they divide

3) Maturation (spermiogenesis)
- Post-meotic spermatids change phenotypes
- round spermatid → elongated spermatid → spermatozoa

23

What is spermiation?

Release of spermatozoa into testicular fluid

24

What cell regulates all stages of spermatogenesis?

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