Lecture 2: Male Reproductive Physiology Flashcards
1
Q
What four things are evaluated in a breeding soundness exam
A
- Bull fitness
- Semen quality
- Libido
- Ability to copulate
2
Q
How is the bull fitness evaluated
A
Look at phenotypic presentation of hoofs, eyes, penis, seminal vesicles (purple)
3
Q
What determines semen quality
A
Sperm motility, sperm morphology, scrotal circumference
4
Q
There is relationship between teste size and ____
A
Timing of puberty in bulls daughter
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
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
7
Q
Where is the site of spermatogenesis
A
Seminiferous tubules
8
Q
What cells eventually become sperm
A
Germ cells
9
Q
What cells are involved in anti-mullerian hormone, androgen binding protein and inhibin
A
Sertoli cells
10
Q
Testes produce two essential products:
A
Sperm and testosterone
11
Q
Seminiferous tubules are encased by
A
Tunisia albuginea
12
Q
Where is the site of sperm production
A
Seminiferous tubules
13
Q
Sperm move through the ___ and into the ___ for storage and further maturation
A
Rete testes and epididymis
14
Q
Upon emission sperm moves out through ____
A
Vas deferens
15
Q
What is spermatogensis
A
Process by which Spermatogonia (germ cells) are converted to spermatozoa (sperms)
16
Q
What is spermogenesis
A
Packaging and maturation of spermatozoa
17
Q
Spermiation
A
Release of spermatozoa from Sertoli cells into lumen of the seminiferous tubules
18
Q
What are the 3 steps of spermatogenesis
A
- Proliferation and differentiation of the Spermatogonia
- Meiosis of spermatocytes
- Spermatogenesis of spermatozoa
19
Q
What are the steps in mitosis
A
- Spermatogonium (1 cell) to two daughter cells
- Spermatognia 2 daughter cells
- Generation of diploid primary spermatocytes
- Results in primary spermatocytes- double stranded DNA
20
Q
What are the steps of meiosis
A
- First meiotic division which takes undifferentiated diploid germ cells to haploid spermatocytes- secondary spermatocytes
- Second meiotic division takes secondary spermatocytes and converts to 16 spermatids
- Results in spermatozoa, single strand of one chromosome
21
Q
During embryonic development germ line cells help form the gonad and become ___
A
Spermatogonia
22
Q
At puberty Spermatogonia undergo mitosis divisions to become _____
A
Primary spermatocytes
23
Q
Each primary spermatocytes then enters the first meiotic division to become _____
A
Secondary spermatocytes
24
Q
Each secondary spermatocytes enters the second round of meiosis producing two ____
A
Spermatids
25
Developing sperm cells do not complete cytokinesis during meiosis, therefore the four daughter cells remain connected forming a ___
Syncytium
26
The syncytium ensures that the haploid cells contain either a ___ or ____ and have access to all gene products available in a complete diploid genome
X or Y chromosome
27
Further maturation in the seminiferous tubule lumen create the ___
Spermatozoa
28
What is the purpose of temporal organization of the Spermatogenic cycle
Continuous production of sperm
29
The spermatogenic wave rate is set constant by ___
Retinoic acid within Sertoli cells
30
T or F: testosterone accelerates rate of the spermatogenic wave
False
31
A new cycle of spermatogenic wave begins every ___ days
12-14 days
32
How many days does it take to make sperm
63 days
33
How many days does it take to migrate to epididymis
14 days
34
What happens to the head of the spermatozoa when it converts from spermatids to spermatozoa
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
35
What is the acrosome
Lysosomes at head of spermatozoa to break into oocyte
36
What is an important component of midpiece in spermatozoa
Mitochondria to power sperm
37
What is the purpose of the tail in spermatozoa
Microtubules move the flagellum tail
38
What forms the blood testes barrier between sertoli cells
Tight junctions
39
Developing sperm move between ___ between Sertoli cells to lumen
Tight junctions
40
What are two important functions for the tight junctions between sertoli cells
1. Prevents immune cells from accessing genetically variant spermatozoa
2. Required for fertility
41
What does gap junctions between Sertoli cells allow
Permit transfer of nutrients
42
Release of spermatids requires what of gap and tight junctions
Breakdown of these connections
43
What are cytoplasmic bridges
Join early spermatids, allow Y sperm to transport necessary gene products to X-sperm
44
___ cells protect sperm and provide physical, metabolic, and nutritional support to developing sperm
Sertoli cells
45
Sertoli cells absorb excess ___ and ___ from developing sperm
Cytoplasm and waste
46
What cells secrete seminiferous tubule fluid to aid in flushing sperm to epididymis
Sertoli cells
47
Sertoli cells producing ____binding protein to sequester ___
Androgen binding protein to sequester T
48
Sertoli cells are stimulated by ___ and ___
T and FSH
49
Sertoli cells release ___
Inhibin
50
During development Sertoli cells secrete ___
Anti-mullerian factor
51
Hypogonadism
Smaller than normal testicular size result in below normal sperm counts
52
The number of Sertoli cells that occur in development determines the ultimate ___ potential of testes
Spermatogenic
53
What is the ampulla
Paired accessory gland, involved in glandular secretion, especially in bull and stallion
54
What ampulla is absent in what species
Boar
55
What are the seminal vesicles
Paired accessory glands that produce prostaglandins, fructose, and clotting factors
56
What does the prostate do
Single accessory gland, produces bicarbonate and make alkaline fluid to combat acidic pH of uterus
57
What are the bulbourethral glands
Paired accessory sex glands that secrete a viscous lubrication
58
T or F: GnRH acts by pulsatile release
True
59
Which hormone sensitizes Sertoli cells to testosterone, promotes inhibin and androgen binding protein secretion
Follicular stimulating hormone (FSH)
60
Which hormone stimulates cholesterol desmolase within leydig cells to produce testosterone
Luteinizing hormone (LH)
61
Inhibin selectively regulates what hormone
FSH
62
T or F: optimal spermatogenesis requires just testosterone and not FSH
False, requires both
63
T or F: adequate spermatogenesis requires the presence of adequate sertoli cells
True
64
What determines the rate limiting step of testosterone synthesis in males
LH
65
LH increases testosterone production by increasing affinity of _____ to cholesterol
Cholesterol desmolase
66
Where is testosterone concentrated in the testes
Seminiferous tubules by androgen binding protein produced by Sertoli cells
67
In order for testosterone to circulate in peripheral circulation must be bound to what
Sex-hormone binding globulin
68
What is the effect of anabolic steroids on teste size
Shrink testes through negative feedback
69
Describe the mechanism in which anabolic steroids shrink testes through negative feedback
Decreases pituitary secretion of gonadotropins, LH and FSH
70
What are some side effects of anabolic steroids acting on HPG negative feedback
1. Reduced sperm production
2. Increased aggression
3. Increased bone growth
71
What temperature does spermatogenesis require
~2 degrees Celsius below body temperature
72
What are some side effects of not keeping testes at cool temperature
Lysosomal destruction of spermatids, produce low sperm counts
73
What two muscles are responsible in regulating testes temperature
Cremaster and Dartos muscle
74
____inputs from the testes to the hypothalamus affect body temperature regulation
Neural
75
Describe the steps in neuroendocrine activation of sexual stimulation
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
What are the two different kinds of penises
Fibroelastic and musculocavernous
77
What type of penis do stallions have
Musculocavernous
78
What type of penis do bulls, rams, and boars have
Fibroelastic
79
What is the Os penis
Rigid structure that surrounds the urethra
80
How does a copulatory lock form between male and female dog
Corpus cavernous expands, bulbis glandis forms a bulb and locks male to female
81
What are the three penile components in all species
Base, shaft glans
82
What is the base of the penis attached to
Attached to the ischial arch and ischiocavernous muscles
83
What portion of the penis contains a central portion that expands, corpus cavernosa and corpus spongiosum
Shaft
84
What part of the penis is at the distal end that is enriched with sensory nerve endings
Glans
85
What is the preputial diverticula and what is a negative side effect
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
How does the erection reflex occur
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
PNS release of ___ in the penis causes smooth muscle relaxation and increased blood flow
Nitric oxide
88
Does PNS or SNS stimulation result in a flaccid penis
SNS
89
Describe the steps of nitric oxide release in erectile tissue
1. NO activates cGMP
2. CGMP activates myosin phosphate in smooth muscle, decreases intracellular Ca2+ and promotes relaxation
3. PDE5 degrades cGMP
90
During flaccid state blood flow into penile tissue is limited by contraction of ____arteries and ___ smooth muscle
Helicine arteries and trabecular smooth muscle
91
During an erect state relaxation of ___ arteries by ___ released from nerve terminals allows blood to flow into cavernous space to induce penile engorgement
Helicine arteries and nitric oxide
92
During erect state compression of ____ venues reduce venous outflow
Subtunical
93
What is intromission
Copulation, insertion of penis into vagina
94
Describe the nerve pathways to emission and ejaculation
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
PNS or SNS: arterial dilation, nitric oxide, ACh, vasocongestion, penile engorgement, stimulation of bulbourethral glands
PNS
96
PNS or SNS: emission and expulsion of semen, contraction of pelvic musculature to enhance sperm mobility
SNS
97
Seminal fluid contains ____ which bind sperm and prevent early acrosomal reactions
Decapacitation factors
98
What is responsible for keeping ejaculate in place in female reproductive tract
Clotting factors
99
Upon ejaculation, seminal decapacitation factors are ___
Removed
100
___ activates sperm, enabling them to respond to appropriate stimuli by the female reproductive tract and acrosome reaction
Capacitation
101
The ___ reaction readies the sperm to meet the oocyte
Acrosome reaction
