Lecture 2: Male Reproductive Physiology Flashcards

1
Q

What four things are evaluated in a breeding soundness exam

A
  1. Bull fitness
  2. Semen quality
  3. Libido
  4. Ability to copulate
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2
Q

How is the bull fitness evaluated

A

Look at phenotypic presentation of hoofs, eyes, penis, seminal vesicles (purple)

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3
Q

What determines semen quality

A

Sperm motility, sperm morphology, scrotal circumference

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4
Q

There is relationship between teste size and ____

A

Timing of puberty in bulls daughter

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5
Q

How do you evaluate libido in breeding soundness exam

A

Arousal involves a cascade of endocrine and neural events that result in erection of the penis, mounting of the sexually responsive female, intromission and ejaculation

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6
Q

What are the 2 compartments and 3 cell types of testes

A

Compartments: seminiferous tubules and interstitial connective tissue

Cells: germ, sertoli, leydig

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7
Q

Where is the site of spermatogenesis

A

Seminiferous tubules

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8
Q

What cells eventually become sperm

A

Germ cells

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9
Q

What cells are involved in anti-mullerian hormone, androgen binding protein and inhibin

A

Sertoli cells

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10
Q

Testes produce two essential products:

A

Sperm and testosterone

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11
Q

Seminiferous tubules are encased by

A

Tunisia albuginea

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12
Q

Where is the site of sperm production

A

Seminiferous tubules

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13
Q

Sperm move through the ___ and into the ___ for storage and further maturation

A

Rete testes and epididymis

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14
Q

Upon emission sperm moves out through ____

A

Vas deferens

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15
Q

What is spermatogensis

A

Process by which Spermatogonia (germ cells) are converted to spermatozoa (sperms)

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16
Q

What is spermogenesis

A

Packaging and maturation of spermatozoa

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17
Q

Spermiation

A

Release of spermatozoa from Sertoli cells into lumen of the seminiferous tubules

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18
Q

What are the 3 steps of spermatogenesis

A
  1. Proliferation and differentiation of the Spermatogonia
  2. Meiosis of spermatocytes
  3. Spermatogenesis of spermatozoa
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19
Q

What are the steps in mitosis

A
  1. Spermatogonium (1 cell) to two daughter cells
  2. Spermatognia 2 daughter cells
  3. Generation of diploid primary spermatocytes
  4. Results in primary spermatocytes- double stranded DNA
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20
Q

What are the steps of meiosis

A
  1. First meiotic division which takes undifferentiated diploid germ cells to haploid spermatocytes- secondary spermatocytes
  2. Second meiotic division takes secondary spermatocytes and converts to 16 spermatids
  3. Results in spermatozoa, single strand of one chromosome
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21
Q

During embryonic development germ line cells help form the gonad and become ___

A

Spermatogonia

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22
Q

At puberty Spermatogonia undergo mitosis divisions to become _____

A

Primary spermatocytes

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23
Q

Each primary spermatocytes then enters the first meiotic division to become _____

A

Secondary spermatocytes

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24
Q

Each secondary spermatocytes enters the second round of meiosis producing two ____

A

Spermatids

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25
Q

Developing sperm cells do not complete cytokinesis during meiosis, therefore the four daughter cells remain connected forming a ___

A

Syncytium

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26
Q

The syncytium ensures that the haploid cells contain either a ___ or ____ and have access to all gene products available in a complete diploid genome

A

X or Y chromosome

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27
Q

Further maturation in the seminiferous tubule lumen create the ___

A

Spermatozoa

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28
Q

What is the purpose of temporal organization of the Spermatogenic cycle

A

Continuous production of sperm

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29
Q

The spermatogenic wave rate is set constant by ___

A

Retinoic acid within Sertoli cells

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30
Q

T or F: testosterone accelerates rate of the spermatogenic wave

A

False

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31
Q

A new cycle of spermatogenic wave begins every ___ days

A

12-14 days

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32
Q

How many days does it take to make sperm

A

63 days

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33
Q

How many days does it take to migrate to epididymis

A

14 days

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34
Q

What happens to the head of the spermatozoa when it converts from spermatids to spermatozoa

A
  1. Head elongates, most cytoplasm is lost
  2. Nucleus remodels- chromatic condensation
  3. Transcription ceases 2 weeks prior to sperm maturation
  4. ;lysosomes aggregate to form acrosome
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35
Q

What is the acrosome

A

Lysosomes at head of spermatozoa to break into oocyte

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36
Q

What is an important component of midpiece in spermatozoa

A

Mitochondria to power sperm

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37
Q

What is the purpose of the tail in spermatozoa

A

Microtubules move the flagellum tail

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38
Q

What forms the blood testes barrier between sertoli cells

A

Tight junctions

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39
Q

Developing sperm move between ___ between Sertoli cells to lumen

A

Tight junctions

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40
Q

What are two important functions for the tight junctions between sertoli cells

A
  1. Prevents immune cells from accessing genetically variant spermatozoa
  2. Required for fertility
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41
Q

What does gap junctions between Sertoli cells allow

A

Permit transfer of nutrients

42
Q

Release of spermatids requires what of gap and tight junctions

A

Breakdown of these connections

43
Q

What are cytoplasmic bridges

A

Join early spermatids, allow Y sperm to transport necessary gene products to X-sperm

44
Q

___ cells protect sperm and provide physical, metabolic, and nutritional support to developing sperm

A

Sertoli cells

45
Q

Sertoli cells absorb excess ___ and ___ from developing sperm

A

Cytoplasm and waste

46
Q

What cells secrete seminiferous tubule fluid to aid in flushing sperm to epididymis

A

Sertoli cells

47
Q

Sertoli cells producing ____binding protein to sequester ___

A

Androgen binding protein to sequester T

48
Q

Sertoli cells are stimulated by ___ and ___

A

T and FSH

49
Q

Sertoli cells release ___

A

Inhibin

50
Q

During development Sertoli cells secrete ___

A

Anti-mullerian factor

51
Q

Hypogonadism

A

Smaller than normal testicular size result in below normal sperm counts

52
Q

The number of Sertoli cells that occur in development determines the ultimate ___ potential of testes

A

Spermatogenic

53
Q

What is the ampulla

A

Paired accessory gland, involved in glandular secretion, especially in bull and stallion

54
Q

What ampulla is absent in what species

A

Boar

55
Q

What are the seminal vesicles

A

Paired accessory glands that produce prostaglandins, fructose, and clotting factors

56
Q

What does the prostate do

A

Single accessory gland, produces bicarbonate and make alkaline fluid to combat acidic pH of uterus

57
Q

What are the bulbourethral glands

A

Paired accessory sex glands that secrete a viscous lubrication

58
Q

T or F: GnRH acts by pulsatile release

A

True

59
Q

Which hormone sensitizes Sertoli cells to testosterone, promotes inhibin and androgen binding protein secretion

A

Follicular stimulating hormone (FSH)

60
Q

Which hormone stimulates cholesterol desmolase within leydig cells to produce testosterone

A

Luteinizing hormone (LH)

61
Q

Inhibin selectively regulates what hormone

A

FSH

62
Q

T or F: optimal spermatogenesis requires just testosterone and not FSH

A

False, requires both

63
Q

T or F: adequate spermatogenesis requires the presence of adequate sertoli cells

A

True

64
Q

What determines the rate limiting step of testosterone synthesis in males

A

LH

65
Q

LH increases testosterone production by increasing affinity of _____ to cholesterol

A

Cholesterol desmolase

66
Q

Where is testosterone concentrated in the testes

A

Seminiferous tubules by androgen binding protein produced by Sertoli cells

67
Q

In order for testosterone to circulate in peripheral circulation must be bound to what

A

Sex-hormone binding globulin

68
Q

What is the effect of anabolic steroids on teste size

A

Shrink testes through negative feedback

69
Q

Describe the mechanism in which anabolic steroids shrink testes through negative feedback

A

Decreases pituitary secretion of gonadotropins, LH and FSH

70
Q

What are some side effects of anabolic steroids acting on HPG negative feedback

A
  1. Reduced sperm production
  2. Increased aggression
  3. Increased bone growth
71
Q

What temperature does spermatogenesis require

A

~2 degrees Celsius below body temperature

72
Q

What are some side effects of not keeping testes at cool temperature

A

Lysosomal destruction of spermatids, produce low sperm counts

73
Q

What two muscles are responsible in regulating testes temperature

A

Cremaster and Dartos muscle

74
Q

____inputs from the testes to the hypothalamus affect body temperature regulation

A

Neural

75
Q

Describe the steps in neuroendocrine activation of sexual stimulation

A
  1. Sensory stimulation
  2. Stimulation of nerves in SON and PVN in hypothalamus
  3. Release of oxytocin from posterior pituitary
  4. Contractions of smooth muscle in distal tail of epididymis and ductus deferens
  5. Transport of spermatozoa into an ejaculatory position
76
Q

What are the two different kinds of penises

A

Fibroelastic and musculocavernous

77
Q

What type of penis do stallions have

A

Musculocavernous

78
Q

What type of penis do bulls, rams, and boars have

A

Fibroelastic

79
Q

What is the Os penis

A

Rigid structure that surrounds the urethra

80
Q

How does a copulatory lock form between male and female dog

A

Corpus cavernous expands, bulbis glandis forms a bulb and locks male to female

81
Q

What are the three penile components in all species

A

Base, shaft glans

82
Q

What is the base of the penis attached to

A

Attached to the ischial arch and ischiocavernous muscles

83
Q

What portion of the penis contains a central portion that expands, corpus cavernosa and corpus spongiosum

A

Shaft

84
Q

What part of the penis is at the distal end that is enriched with sensory nerve endings

A

Glans

85
Q

What is the preputial diverticula and what is a negative side effect

A

Congenital deformity in the boar that causes boars penis to ball up and enter diverticula instead of sow and therefore ejaculates there and pregnancy does not occur

86
Q

How does the erection reflex occur

A

1.stimulation of mechanoreceptors in glans penis
2. PNS to bulbourethral glands and urethral glands, PNS to penile arterials, decrease SNS to penile arterials
3. Penile arteriole dilate, mucus produced
4. Erection
5. Compress veins- negative feedback

87
Q

PNS release of ___ in the penis causes smooth muscle relaxation and increased blood flow

A

Nitric oxide

88
Q

Does PNS or SNS stimulation result in a flaccid penis

A

SNS

89
Q

Describe the steps of nitric oxide release in erectile tissue

A
  1. NO activates cGMP
  2. CGMP activates myosin phosphate in smooth muscle, decreases intracellular Ca2+ and promotes relaxation
  3. PDE5 degrades cGMP
90
Q

During flaccid state blood flow into penile tissue is limited by contraction of ____arteries and ___ smooth muscle

A

Helicine arteries and trabecular smooth muscle

91
Q

During an erect state relaxation of ___ arteries by ___ released from nerve terminals allows blood to flow into cavernous space to induce penile engorgement

A

Helicine arteries and nitric oxide

92
Q

During erect state compression of ____ venues reduce venous outflow

A

Subtunical

93
Q

What is intromission

A

Copulation, insertion of penis into vagina

94
Q

Describe the nerve pathways to emission and ejaculation

A
  1. Intromission
  2. Sensory stimulation of glans penis
  3. Sudden and powerful contraction of urethra lips, bulbospongiosus and ischiocavernous muscles
  4. Expulsion of semen
95
Q

PNS or SNS: arterial dilation, nitric oxide, ACh, vasocongestion, penile engorgement, stimulation of bulbourethral glands

A

PNS

96
Q

PNS or SNS: emission and expulsion of semen, contraction of pelvic musculature to enhance sperm mobility

A

SNS

97
Q

Seminal fluid contains ____ which bind sperm and prevent early acrosomal reactions

A

Decapacitation factors

98
Q

What is responsible for keeping ejaculate in place in female reproductive tract

A

Clotting factors

99
Q

Upon ejaculation, seminal decapacitation factors are ___

A

Removed

100
Q

___ activates sperm, enabling them to respond to appropriate stimuli by the female reproductive tract and acrosome reaction

A

Capacitation

101
Q

The ___ reaction readies the sperm to meet the oocyte

A

Acrosome reaction