Male Reproduction Flashcards
1
Q
Label the following
A
2
Q
What are the two primary functions of the gonads (testes)?
A
1) Spermatogenesis
2) Synthesis of testosterone and Inhibin
3
Q
What structures make up the duct system?
(hint: REEVE)
A
R = rete testis
E = efferent ductules
E = epididymis
V = vas deferens
E = ejaculatory duct
4
Q
What are the three glands in male reproduction?
A
1) Bulbourethral gland
2) Prostate
3) Seminal Vesicles
5
Q
The testes are suspended outside of the body in a sac known as the ___
A
scrotum
6
Q
Production of spermatozoa requires a lower than normal internal body temperature because ___ in spermatocytes may release enzymes that can lead to regression of germinal cells
A
lysosomes
7
Q
Label this teste:
A
8
Q
The teste is divided into ___, each of which has loops of _______ (where spermatoza mature)
A
lobules; seminiferous tubules
9
Q
Where do spermatozoa mature?
A. Rete Testis
B. Epididymus
C. Seminiferous Tubules
A
C. Seminiferous tubules
10
Q
Sperm moves through ____→ ____ to reach the _____ for
packaging
A
rete testis → efferent ductules → epididymus
11
Q
The walls of the seminiferous tubules contain ____ and ___, (which will become spermatozoa)
AND ____
(provide protection and crucial nutrients)
A
1) spermatogonia (germ cells)
2) spermatocytes (developing sperm)
3) Sertoli cells
12
Q
What three cells are in the walls of the seminiferous tubule?
A
- Sertoli cells
- Spermatogonia
- Spermatocyte
13
Q
What is found in the lumen of the seminiferous tubule?
A
1) Immotile spermatozoa
2) Luminal fluid secreted by sertoli cells
14
Q
Where do spermatozoa acquire motility and complete their maturation?
A
Epididymis
15
Q
The build up pressure of the luminal fluid pushes the spermatozoa through the ____ and ____ to the ____
A
Seminiferous tubules → rete testis → epididymis
16
Q
Which cells are located between the seminiferous tubules and are responsible for the synthesis of testosterone?
A
Leydig cells
17
Q
Unlike female oogenesis, spermatogenesis begins at ___. Why?
A
puberty
- all of the phases of spermatogenesis require high concentrations of testosterone
18
Q
Three major stages of spermatogenesis?
A
stage 1: mitotic proliferation
stage 2: meiosis
stage 3: packaging
19
Q
Where do the first two stages of spermatogenesis (mitotic proliferation and meiosis) occur?
A
Seminiferous tubules
20
Q
Where does packaging, the final stage of spermatogenesis, occur?
A
Epididymis
21
Q
True or False: Only the final stage of spermatogenesis requires high testosterone
A
False - all stages require high levels
22
Q
At which stage of spermatogenesis are spermatogonia (germ cells) converted to 1 spermatocytes?
A. Meiosis
B. Mitotic Proliferation
C. Packaging
A
Mitotic proliferation
23
Q
When are elevated testosterone levels achieved in males?
A
Puberty
24
Q
True or False: Both mitosis and meiosis are testosterone dependent
A
True
25
Products of oogenesis vs. spermatogenesis?
Oogenesis - 1 haploid daughter cell
Spermatogenesis - 4 haploid daughter cells
26
Each primary spermatocytes ultimately produces ___ spermatozoa with 23 chromosomes and the characteristic head, mid-piece, and tail
four (4)
27
Each Sertoli cells extends from the ___ to the ___ of the seminiferous tubule
basal membrane; lumen
28
The developing sperm occupy the space between ___ cells
Sertoli
29
What type of junctions keep Sertoli cells together?
Tight junctions (develop during puberty)
30
Function of Tight Junctions?
1) provide compartmentalized environment for various phases of sperm differentiation
2) prevent deleterious agents from entering LUMINAL space of seminiferous tubules
31
Tight junctions are also known as _____
blood-testes barrier
32
Tight junctions define what two compartments within the wall of the seminiferous tubules?
1) Outer Basal Compartment
2) Inner Luminal Compartment
33
In which compartment of the seminiferous tubules does spermatogonia undergo several MITOTIC DIVISIONS to become 1 spermatocytes?
A. Outer Basal Compartment
B. Inner Luminal Compartment
A. Outer Basal Compartment
34
In order to progress in their development, the 1 spermatocyte has to move through the ___ compartment to the ___ compartment.
The tight junctions break briefly to allow passage fo spermatocytes, then reform
basal ; adluminal (luminal)
35
In which compartment of the seminiferous tubules does the primary spermatocyte undergo meiosis and differentiate (without further division) until they reach their final form (spermatozoa)
A. Outer Basal Compartment
B. Inner Luminal Compartment
B. Inner Luminal (adluminal) Compartment
36
Once the spermatozoa are formed, ____ retract and spermatozoa are released into the ___ of the seminiferous tubules
Sertoli cells; lumen
37
____ is the final maturation step in the male reproductive tract, during which immotile spermatozoa become ___, acquire ___, and become more _____
Packaging; elongated; motility; concentrated
38
Where does packaging take place? How long does it take?
Epididymis (14 days)
39
After immature spermatozoa pass through ____, which joint to form a single duct within the epididymis
rete testis
40
____: structure that contains convoluted tubules of smooth muscle, lined with secretory epithelium
Epididymides
41
True or False: The final maturation of sperm depends on adequate stimulation of epididymis by high testosterone levels
True
42
Which male reproductive structure is responsible for absorbing most of the intra-tubular fluid, thereby concentrating the sperm
Epididymis
43
Once epididymis absorbs most of the intratubuar fluid, there isn'y enough hydrostatic pressure to push sperm forward. Spermatozoa cannot move independently because they are too tightly packed.
At this stage: how do the sperm progress through the duct system?
Peristaltic contractions of the smooth muscle cells of the epididymis and vas deferens
44
True or False: Mature, viable spermatozoa are stored for a few days in the ampulla of the vas deferens, then moved to the epididymis until they are ejaculated
False - mature, viable spermatozoa are stored for a few days in the epididymis → vas deferens → ejaculated
45
How many sperm are made daily?
How many oocytes are made monthy?
30,000,000 sperm/day
1 oocyte/month
46
During ejaculation, the concentrated sperm are mixed with secretions from the ________
accessory glands
47
Most of the constituents of semen are made by the three accessory sex glands. Namely:
1) Bulbourethral gland
2) Seminal vesicle
3) Prostate
48
_____: bilateral glands that empty into the ampulla of the ductus deferens
_____: surrounds the ejaculatory duct and urethra and secretes alkaline fluid
____: secrete a mucus-like substance that cleans and lubricates urethra prior to ejaculation
Seminal vesicles
Prostate
Bulbourethral Glands
49
What is the function of the seminal vesicles?
Dilute sperm → motility
(note: contains AA, PG, fibrinogen)
50
True or False: The alkaline fluid secreted by the prostate contribute an alkaline component to the semen, which is important for sperm motility and survival in acidic vagina
True
51
Sperm cells need to undergo ___ to acquire ability to interact with oocyte. This takes place in fallopian tubes.
capacitation
52
True or False: In males, there are variations in frequency of GnRH pulsatile release
False - there are NO variations
53
In males, pulsatile release of GnRH stimulates release of ___ and ____
LH and FSH
54
In males, LH stimulates synthesis of ____ in testes
FSH stimulates multiple functions of the ___ cells
LH = testosterone synthesis (leydig)
FSH = sertoli cells
55
Compare and contrast positive feedback in males vs. females
In females:
-Positive feedback of estrogen right before ovulation; progesterone, however, is always regulated via negative feedback
In males:
- No positive feedback in HPA
56
Sertoli cells are homologous to ____ cells (female reproduction)
Sertoli = Granulosa cells
57
As part of negative feedback, the plasma testosterone decreases amplitude of ____ release pulses in hypothalamus and blunts the release of ____ (major extent) and ____ (minor extent)
GNRH; LH; FSH
58
In males: Inhibin is made by ___ cells. As Inhibin increases, there is a decrease of ___ (negative feedback)
In females: Inhibin is made by ____ cells. As Inhibin increases, there is a decrease of ____ (negative feedback)
In males:
- Inhibin is made by Sertoli cells
- ↓ FSH
In females:
- Inhibin is made by Granulosa cells
- ↓ FSH
59
True or False: In males, LH receptors are expressed on Sertoli cells
False - in males, LH-R are NOT expressed on Sertoli cells
60
In males, LH binds to its receptors, located exclusively on ____ cells, stimulating testosterone from ____
Leydig cells; cholesterol
61
Testosterone diffuses into the plamsa and to the adjacent Sertoli, where it is required for both ___ and ___ of spermatogonia
mitosis; meiosis
62
True or False: Local production of testosterone is critical to spermatogenesis
True
- Testicular testosterone concentration >>>> plasma testosterone
63
What cell secreted androgen binding protein? What does this allow for?
The sertoli cell secretes androgen binding protein
- allows for higher testosterone concentration to be reached within testes
64
FSH acts on ___ cells (nurse cells) to promote spermatogenesis
sertoli cells
65
True or False: FSH-R are restricted to Sertoli cells in males
True
66
Although ___ and ___ are required for spermatogenesis, ___ in appears to be particularly essential for early functions in the process and for sensitizing sertoli cell to testosterone
testosterone and FSH; FSH
67
FSH stimulates what three things?
1) Synthesis of inhibin / androgen-binding protein (sertoli cells)
2) Formation of tight junctions
3) Synthesis of seminiferous tubular fluid
68
What are the eight roles of Sertoli cells in spermatogenesis?
(hint: TSA PIMP G)
1) tight junctions
- at puberty, under FSH stimulation
2) secrete seminiferous tubule fluid
- FSH stimulation
3) androgen binding protein
- FSH stimulation
- ABP binds to testosterone, leading to high testosterone concentration in repro tract
4) phagocytose defective sperm
- FSH stimulation
5) INHIBIN
- FSH stimulation
- local: promotes spermatogenesis
- systemic: suppress FSH
6) Mullerian Duct Inhibiting Factor
- secreted in utero
- causes regression of female duct system
7) Paracrine agents
- in response to testosterone and FSH
- stimulates sperm dif/maturation
8) generates nutrients and paracrine GF
- direct cellular dif/modulate leydig fxtion
69
Where is the majority of sperm made?
Testes
70
Of the five enzymatic steps involved in converting cholesterol into testosterone, how many lead to synthesis of androstendione and DHEA in the adrenal cortex?
Four
- note: step 5 takes place in testes
71
What is the major androgen made by the adrenal gland?
Androstenedione
- less potent than testosterone
72
Why can androstenidone not support spermatogenesis in the testes?
1) less potent than testosterone
2) plasma [androstenidone] is lower than the [testosterone] in the testes
73
Androgen synthesis occurs in the ___ and ____ glands
1) testes
2) adrenal glands
74
Why can men who take exogenous anabolic steroids become infertile?
- Negative feedback is reinforced
- Therefore: ↓LH = ↓ testosterone made
- Hypothalamus/Pituitary will not respond
- ↓ FSH = ↓ ABP made by sertoli cells = ability to concentrate testosterone locally will be reduced
75
Two major effects of taking exogenous anabolic steroids on men?
1) Infertility
- Decline in intra-testicular testosterone → impaired spermatogenesis
2) Gynecomastia
- Excess plasma androgens →adipose/muscle (aromatase) → estrogen
76
How is testosterone transported?
SSBG/TeBG (made in liver) + albumin
- note: TeBG binds both estrogen and testosterone in the plasma, but has greater affinity for testosterone
77
What is the major end product of testosterone metabolism?
Androsterone
78
True or False: The adrenal cortical production of androsterone accountts for a large fraction of 17-ketosteroids excreted in the urine (and, therefore, 17-ketosteroids are NOT a reliable indicator of testicular androgen secretion)
True
79
Testosterone is converted to ____ and ______
DHT (dihydrotestosterone) via: 5a-reductase
Estradiol
via: aromatase (sertoli cells + adipose)
80
Where is 5a reductase primarily found?
- Skin
- Prostate
81
Which class of drugs are used to treat prostate cancer and male pattern baldness?
5a-reductase inhibitors
82
What molecules are required for spermatogenesis?
(hint: TELLS F)
T - high testosterone
E - epididymis
L - LH
L - lydig cells
S - sertoli cells
F - FSH
83
Most of the estrogen in the plasma of men is derived from the ___ converstion of testosterone/androstendione to estradiol or estrone. This occurs primarily in the ____
peripheral conversion; adipose tissues
84
True or False: Extremely high levels fo estrogen is bad for spermatogenesis and prolonged exposure to xenoestrogens can diminish sperm count
True
85
Absence of estrogen in males as a result of genetic mutation results in ___ and ____
severe osteoporosis; delayed closure of epiphyses
86
How do men develop BPH?
- As men age, their estrogen levels rise
- Estrogen may induce expression of androgen receptors on prostate gland, thereby favoring growth of prostate gland
87
What molecule is permissive for LH-stimulated testosterone synthesis?
A. GHRH
B. GnRH
C. Prolactin
D. Growth Hormone
E. Estrogen
C. Prolactin
88
True or False: Prolactin increases the number of androgen receptors in prostate and seminal vesicles
True
89
What happens in the case of a prolactinoma?
Prolactin is secreted at HIGH concentrations
- Therefore: GnRH is inhibited, which suppresses secretion of FSH and LH → decreased testosterone production → impotence
90
As one ages (60 to 70 years old), production of sperm decreases. How does this affect the LH and FSH levels in men?
Increases FSH/LH levels
91
AE associated with testosterone replacement therapy used to treat men with hypogonadism
- Increase Hg and hemocrit
- Fluid retention
- Sleep apnea
- Prostate enlargement
- Cancer????
92
AE associated with testosterone replacement therapy used to treat men with hypogonadism
- Increase Hg and hemocrit
- Fluid retention
- Sleep apnea
- Prostate enlargement
- Cancer???
93
Why is gynecomastia less likely to develop in a person taking TRT vs. body builder?
In TRT, the objective is to re-est. physiological condition of testosterone, while in the case of the body builder, the androgens plasma levels rise way beyond normal
94
The common form of contraception in women in inhibiting LH/FSH. Why does this nor work in men?
- Administration of exogenous testosterone does not completely stop spermatogenesis
95
____: contraceptive procedure by which the vas deferens are tied off and sealed, preventing translocation of sperm to ejaculatory ducts and external environment
Vasectomy
96
True or False: In a vasectomy, sperm build up and is eventually re-absorbed, but there is not liquid accumulation because seminiferous liquid is reabsorbed by the epididymis.
True
97
True or False: Vasectomy lowers production of testosterone :(
False - does not affect leydig cells
98
How is the supply of spermatogonia maintained throughout a man's life?
One differentiating cell drops out of cascade and reverts to the spermatagonium stage
99
___ → ___ → ___ → ____ → ____
spermatagonia
↓ [mitosis/differentiation]
1 spermatocyte
↓ [1st meiotic division]
2 spermatocyte
↓ [2nd meiotic division]
spermatid
↓ [differentiation]
spermatazoa
