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Repro > Spermatogenesis > Flashcards

Spermatogenesis Flashcards

1
Q

what is a sperm called when it is in the shape of a round cell?

A

spermatid

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2
Q

what is a sperm called when it is elongated with a tail?

A

spermatozoa

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3
Q

how long does it take to produce sperm?

A

57-60 days

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4
Q

why does FSH appear in lower spikes than LH?

A

it has a longer half life, so don’t need as much as it will stay in the system longer on its own

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5
Q

what does an LH spike cause?

A

a rise in testosterone

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6
Q

why does LH only appear in spikes as opposed to continuous release?

A

LH receptors in Leydig cells will become desensitized to LH if it is constantly released

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7
Q

give the 4 steps of the male feedback loop, including 3-4A and 3-4B

A
  1. GnRH release from hypothalamus (tonic only)
  2. release of FSH and LH from anterior pituitary
    3A. FSH targets sertoli cells to:
    -promote spermatogenesis
    -produce inhibin
    -produce ABP
    4A. inhibin has negative feedback effect on anterior pituitary
    3B. LH targets Leydig cells to produce testosterone, which can diffuse into sertoli cells and bind to ABP, or is converted to E2, which will have negative feedback on the hypothalamus and anterior pituitary
    4B. testosterone can go into circulation and cause negative feedback on ant pit and hypothalamus
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8
Q

list the 3 main phases of spermatogenesis

A
  1. spermatocytogenesis
  2. meiotic phase
  3. spermiogenesis/differentiation
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9
Q

what is spermatocytogenesis also called?

A

the proliferative phase

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10
Q

what happens during spermatocytogenesis?

A

mitosis, the replication of spermatogonia

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11
Q

what do spermatogonia become during the meiotic phase?

A

primary spermatocytes that become secondary spermatocytes which become round spermatids

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12
Q

how many phases are there in spermiogenesis?

A

4

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13
Q

are there any cell divisions in spermiogenesis?

A

nope

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14
Q

what shift takes place during spermiogenesis?

A

morphological shift from round spermatid to specialized spermatozoa

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15
Q

how many chromatids are in primary spermatocytes?

A

4, 4C

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16
Q

how many chromatids are in spermatogonia?

A

2, 2C

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17
Q

how many chromatids are in secondary spermatocytes?

A

2, 2C

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18
Q

what is the first haploid version of a sperm cell and how many chromatids does it have?

A

round spermatid 1C

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19
Q

how long does the whole spermatogenesis process take?

A

about 61 days

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20
Q

describe Type A and Type B spermatogonia

A

Type A: stay behind to make more generations, keep undergoing regular mitosis
Type B: enter meiotic phase to become spermatozoa

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21
Q

how many mitotic divisions to spermatogonia undergo to become primary spermatocytes?

A

species dependent! anywhere from 2-6 divisions, yielied 4 to 64 potential daughter cells

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22
Q

what forms between daughter cells undergoing mitosis?

A

cytoplasmic bridges

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23
Q

list 5 things that cause/increase/effect apoptosis of germ cells

A
  1. season: seasonally reproductive animals like rams lower in spring and summer
  2. disease
  3. trauma or heat
  4. hormone levels
  5. normal part of spermatogenesis
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24
Q

list the 2 purposes of stem cell renewal as it relates to spermatogenesis

A
  1. to keep spermatogenesis going indefinitely

2. replenish testis in case of injury, trauma, or high heat

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25
Q

what happens in spermiogenesis? big thing here

A

round spermatids become elongated spermatozoa

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26
Q

what is the first step of spermiogenesis?

A

the golgi phase

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27
Q

list the 4 steps of spermiogenesis

A
  1. the golgi phase
  2. cap phase
  3. acrosomal phase
  4. maturation phase
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28
Q

what happens in the golgi phase of spermiogenesis? (3)

A
  1. golgi apparatus migrates to anterior end of sperm head
  2. centrioles migrate to posterior end
  3. golgi apparatus secretes acrosomic vesicle, which will become the acrosome
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29
Q

what happens to the proximal centriole during the golgi phase of spermiogenesis?

A

it becomes the implantation socket

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30
Q

what happens to the distal centriole during the golgi phase of spermiogenesis?

A

it will bexome the axoneme

31
Q

what happens during the cap phase of spermiogenesis? (3)

A
  1. acrosome forms distinct cap over nucleus
  2. golgi are moving away from the nucleus towards the posterior region
  3. formation of primitive flagellum membranes begin to form
32
Q

what happens during the acrosomal phase of spermiogenesis? (3)

A
  1. acrosome continues to spread around nucleus
  2. continued growth of flagellum
  3. formation of manchette
33
Q

what is the manchette?

A

a series of microtubules associated with elongation of the nucleus

34
Q

what happens during the maturation phase of spermiogenesis? (4)

A
  1. golgi migrate toward tail and disappear
  2. manchette has organized to form the post-nuclear cap
  3. mitochondria migrate down to the midpiece and clister around midpiece, forming the helix
  4. dense outer fibers form on sheath of flagellum
35
Q

what is the end result of the acrosomal phase of spermiogenesis?

A

now the spermatid is a spermatozoa!

36
Q

define spermiation

A

the release of spermatozoa from sertoli cell into the lumen of the seminiferous tubule

37
Q

when does spermiation occur?

A

after spermatogenesis

38
Q

what happens during spermiation (to remaining cytoplasm)?

A

sertoli cell phagocytizes (eats) the remaining cytoplasm

39
Q

what is the cytoplasmic droplet?

A

the remnant of the spermiation process

40
Q

how long after a deleterious event occurs are effects detected in an ejaculate?

A

2-4 weeks delay

41
Q

how long after a deleterious event is there normal restoration of spermatogenesis?

A

6-12 weeks

42
Q

why are breeding soundness exams not always effective or telling of spermatogenesis?

A

due to the delay in effects on spermatogenesis after a deleterious event

43
Q

what stages of spermatogenesis do deleterious events normally imapct?

A

mitotic and meiotic stages

44
Q

what are stages defined as in terms of spermatogenesis?

A

specific cellular associations within a small segmentt of a seminiferous tubule

45
Q

are stages the same length in time?

A

no

46
Q

how many stages are in spermatogenesis for most domestic species?

A

8

47
Q

how many layers of germ cells, or generations, does each stage of spermatogenesis have?

A

4-5

48
Q

what is a cycle in spermatogenesis?

A

one time through stages 1-8, a progression through sequence of all stages

49
Q

for a bull, how many cycles does it take to form spermatozoa?

A

4.5

50
Q

how long is one cycle of spermatogenesis for a bull?

A

13.5 days

51
Q

do different stages on development take the same amount of time?

A

no

52
Q

what is the significance of a boar having a shorter spermatogenesis cycle than a human?

A

you will see evidence of a testicular injury quicker

53
Q

describe the importance of the coordination of stages of spermatogenesis in a seminiferous tubule to produce waves

A

some portion of the seminiferous tubule is ALWAYS releasing sperm

54
Q

what does the site of reversal in a seminiferous tubule do?

A

ensures that flow and movement of sperm in NOT continuous from one side to the other

55
Q

what does the compartment inside the basement membrane of a seminiferous tubule contain?

A

sperm cells in all stages of development

56
Q

what 5 things does the vascular system of the interstitial tissue provide?

A
  1. nutrients
  2. oxygen
  3. growth factors
  4. hormones
  5. immune cells
57
Q

what form of a sperm cell is the first to cross the blood testis barrier?

A

primary spermatocyte

58
Q

lisy the 3 compartments of a seminiferous tubule

A
  1. basal
  2. adluminal
  3. lumen
59
Q

what phase of spermatogenesis takes place in the basal compartment of a seminiferous tubule?

A

mitosis

60
Q

what types of sperm cells are found in the basal compartment of the seminiferous tubules? (2)

A

spermatogonia (A and B)

primary spermatocytes

61
Q

what lies between the basal and adluminal compartments of a seminiferous tubules?

A

blood testis barrier

62
Q

what phase of spermatogenesis takes place in the adluminal compartment of a seminiferous tubule?

A

meiosis

63
Q

what types of sperm cells are found in the adluminal compartment of a seminiferous tubule? (3)

A

primary spermatocytes
secondary spermatocytes
spermatids

64
Q

what phase of spermatogenesis takes place in the lumen of a seminiferous tubule?

A

spermiation

65
Q

what is the blood testis barrier made of?

A

sertoli cells and associated tight junctions

66
Q

when does the blood testis barrier first appear and why?

A

first appears at puberty due to increase in gonadotropins, and because body isnt even producing sperm until puberty so why need a barrier until then?

67
Q

what induces the blood testis barrier?

A

FSH

68
Q

after puberty, what maintains the blood testis barrier?

A

FSH and/or testosterone

69
Q

what is the blood testis barrier ESSENTIAL for?

A

meiosis

70
Q

what do sertoli cells determine by manipulating the environment around primary spermatocytes? (2)

A

what enters meiosis, what completes meiosis

71
Q

what does the destruction of tight junctions cause?

A

impairment of meiosis

72
Q

what 5 things can cause destruction of tight junctions and subsequent imparment of meiosis?

A
  1. heat
  2. heavy metals (which can be consumed in forage)
  3. endocrine disruptors
  4. pesticides
  5. lack of FSH or testosterone
73
Q

what 3 things cause variation in sperm production?

A
  1. testis size
  2. efficiency of spermatogenesis (mitotic division and degeneration of sperm cells)
  3. length of spermatogenesis

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