(C) - Reproduction > 5 - Gametogenesis > Flashcards

5 - Gametogenesis Flashcards

(23 cards)

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1
Q

How is genetic variation ensured during meiosis?

A
  • Independent assortment
  • Random segregation
  • Crossing over (in bivalents)
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2
Q

What are the differences between male and female gametes?

A
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3
Q

What is spermatogenesis and where/how does it occur?

A
  • Haploid cells from germ cells
  • In seminiferous tubules
  • Spermatogonia in basal compartment divide by mitosis to form two primary spermatocytes, one replacing spermatogonia and one undergoes meiosis I to form secondary spermatocytes
  • Meiosis II to make 4 spermatids
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4
Q

What is the blood-testes barrier?

A

- Basal compartment = spermatogonia

- Adluminal compartment = spermatids

  • Leydig cells, next to sertoli cells, secrete testosterone
  • Barrieer prevents autoimmune destruction of genetically diverse sperm
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5
Q

What are the two different types of spermatogonium?

A

D = dark (quiescent state if needed)

P = pale

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6
Q

What is a spermatogenic cycle and wave?

A

Cycle: time taken for spermatids at the same stage in the cycle to reappear within a given segment. approx 16 days

Wave: distance between groups of spermatids at the same level of maturation.

Allows male to always be fertile

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7
Q

What is spermiogenesis?

A
  • Spermatids become spermatazoa (mature sperm)
  • In lumen of seminiferous tubule non-motile sperm becomes motile
  • Process complete by epididymis
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8
Q

What is the structure of a sperm?

A

- Head: nucleus and acrosome layer for when touches ova

- Tail: motility. lots of mitochondria for ATP to provide energy for the flagella

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9
Q

What is sperm capacitation?

A
  • Occurs in female reproductive tract
  • Spermatozoa now fertile
  • Acrosome reaciton allows it to get through zona pellucida
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10
Q

Where is the derivatives of semen?

A

- Fructose: to stop competition with lactobacilli for glucose

- Zinc: high conc means low motility

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11
Q

What is the process of oogenesis before birth?

A
  • Germ cells from yolk sac go to ovary and form oogonia, which proliferate by mitosis
  • All enter meiosis I and stop at prophase = primary oocytes
  • End of 3rd month surrounded by flat epithelial cells called follicular cells = primordial follicles
  • Oogonia already undergoing atresia at this point
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12
Q

After birth how does oogenesis continue in general?

A
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13
Q

Describe the three phases of a maturing oocyte.

A
  • Preantral: 15-20 follicular cells change from flat to cuboidal stratified. Called granulosa cells. These cells secrete glycoprotein on oocyte to form zona p. Primary follicle

- Antral: Fluid filled spaces between granulosa cells. Collective space called antrum, secondary follicle. Outer fibrous layer forms theca interna and externa.

- Preovulatory: LH surge so follicle completes meiosis I. One chosen to go to maturity - Graafian follicle. Will start meiosis II 3hrs before ovulation but stops in metaphase. Only completes meiosis II if fertilised, polar bodies discarded. No fertilisation the oocyte degrades after 24 hours

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14
Q

What other cells are released with the ova?

A
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15
Q

How does the process of actual ovulation occur?

A
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16
Q

Once the oocyte has left the ovary, what happens to the left over theca interna/externa cells?

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A
  • Dies after 14 days and forms a mass of scar tissue called corpus albicans
17
Q

How is the oocyte transported down the uterine tube?

18
Q

What happens to the corpus luteum if fertilisation occurs?

19
Q

What are the main differences between oogenesis and spermatogenesis?

20
Q

What is the histological structure of an ovary?

21
Q

Label the following histological images to explain what follicle is being shown in the ovary.

22
Q

What does the corpus luteum look like histologically?

23
Q

What week of embryological development do the germ cells arise?

(C) - Reproduction
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