jones Flashcards
1
Q
what is the HPG axis
A
The hypothalamic–pituitary–gonadal axis (HPG axis) refers to the hypothalamus, pituitary gland, and gonadal glands t regulate development, reproduction and aging
2
Q
where do endocrine glands secrete hormones
A
into the bloodstream; the hormones travel to and act on other organs or tissues
3
Q
what is the hypothalamus
A
part of the forebeain that regulates core (homeostatic) functions eg metabolism, growth, reproduction and stress
4
Q
what is a critical component of the reproductive system that is secreted for the hypothalamus
A
peptide hormone gonadotrophin releasing hormone (GnRH)
5
Q
anterior pituitary is an endocrine gland. made up of different groups of cells which all secrete different hormones. which cells secrete FSH and LH
A
gonadotrophs
6
Q
gonadotroph proliferation and hormone production is positively regulated by signalling through a what
A
G-protein coupled receptor GnRHr
7
Q
activation of G-protein coupled receptor causes gonadotrophs to secrete
A
FSH and LH
8
Q
there are 3 main types of sex steroid. these are..
A
progesterones, androgens and oestrogen
9
Q
all sex steroids are derived from which common precursor
A
cholesterol
10
Q
once inside a cell, steroid-receptor complexes bind to steroid response elements on DNA and impact on transcription
A
T
11
Q
what does oestrogen bind
A
oestrogen receptor on the gonadotroph
12
Q
binding of oestrogen to its receptor on gonadotroph leads to what
A
complex translocates into nucleus and mediates negative transcriptional control of target genes through oestrogen response elements
13
Q
binding of oestrogen to the oestrogen receptor on the gonadotroph leads to the reduction of what
A
production of FSH and LH
14
Q
male and female gonadal cells express inhibins and activins what do these do
A
bind to receptors on gonadotroph cell and regulate FSH and LH expression
15
Q
feedback control happens at the level of what
A
pituitary, hypothalamus or testes and ovaries
16
Q
LH and FSH output is predominantly regulated by secretory products of which female organ
A
ovary
17
Q
which secretory products from ovary exert a depressent effect on gonadotrophin output (FSH and LH)
A
oestrogens, progesterones and inhibins
18
Q
which secretory products from ovary cause a surge on gonadotrophin output (FSH and LH)
A
activin, oestradiol
19
Q
oestradiol acts to negatively regulate LH expression at low concs but when its at high concentrations..
A
it acts to positively regulate expression
20
Q
progesterone has 2 effects. these are
A
high conc seen in luteal phase - enhances negative feedback of oestradiol
- at certain levels of progesterone, positive feedback of oestradiol is blocked
21
Q
inhibins selectively negatively regulate … secretion
A
FSH
22
Q
what cells does FSH act on
A
granulosa cells
23
Q
what cells does LH act on
A
thecal cells
24
Q
what is the difference in regulation of gonadotrophs in males
A
mechanisms similar to females except that there is absense of positive feedback in male (continual production in male)
25
which cells secrete androgens (mainly testosterone)
leydig cells
26
leydig cells secrete androgens that exerts a negative feedback response which causes a decrease in ....
GnRH
27
as in females, what acts at the level of the pituitary to supress FSH secretion
inhibin
28
GnRH is essential for gonadal function. when there is destruction of GnRH neurons what happens
gonadal atrophy
29
when do GnRH pulses begin
puberty
30
what are the 2 ways in which alterations of the output of LH and FSH can be achieved
- increasing or decreasing the amplitude or frequency of GnRH pulses
- modulating the response of gonadotrophs to the pulses
31
kisspeptin 1 is a 54 amino acid neuropeptide that binds to which receptor on GnRH neurons
GPR54
32
kisspeptin is a potent GnRH stimulator T/F
T
33
binding to oestrogen to kiss1 positie neurons results in...
negative feedback by decreasing GnRH expression
34
leptin is a peptide hormone produced by...
adipocytes
35
leptin levels relate to ... levels
fat
36
leptin may be involved in activating the HPG axis at puberty via...
KISS1
37
leptin is necessary for what to proceed
puberty
38
what is spermatogenesis
the production of spermatozoa from spermatogonial stem cells
39
the testes are the site of spermatogenesis. what do the testes house
seminiferous tubules
40
what is the epididymis the site of
sperm storage and maturation
41
what is the vas deferens important for
transport of sperm from epididymis dueing ejaculation
42
what does the seminal vesicle produce
mucus secretion which aids mobility of sperm
43
what does the prostate gland produce
an alkaline secretion that neutralises acidity of any urine in urethra
44
what is the urethra
a tube that carries urine and sperm out of the body
45
the testis have 2 main overlapping functions
- produce androgens foe sexual differentiation
| - to produce spermatozoa for sexual reproduction
46
testes have stroma consisting of blood vessels, lymph and leydig cells. what do leydig cells synthesise and secrete
steroid hormones
47
what are primordial germ cells
gamete precursors
48
- The PGC population expands by mitosis and migrates to the genital ridge primordium by 6 weeks gestation
T
49
the germinal epithelium eventually bcomes which 2 types of cells
```
sertoli cells (male)
granulosa cells (female)
```
50
when does spermatogenesis begin and how many sperm are produced perday
begins at puberty
| about 100 million sperm produced per day
51
what is the final differentiation step in spermatogenesis called
spermiogenesis
52
spermatogenesis involves mitosis and meiosis T/F
T
53
how many mature spermatozoa does spermatogenesis produce
4
54
what happens in spermatogenesis
diploid cell undergoes lots of mitotic divisions to self renew. at some point differentiates and goes down spermatogenesis route. primary spermatocytes undergo meiosis twice to generate 4 identical in size but genetically diverse spermatids
55
what are spermatogonial stem cells
self regenerating pool which undergo rounds of mitosis
56
where is it determined whether spermatogonia will divide or differentiate?
seminiferous tubules
57
immature sperm cells are attached to sertoli cells. where do they move when they differentiate
lumen of seminiferous tubules
58
what happens in spermiation
cytoplasmic bridges are broken and fully differentiated sperm are released into lumen
59
what part of sperm is important for fertilisation
acrosome cap
60
the mid piece of sperm contains the...
mitochondria
61
when a spermatid develops into a mature spermatozoa, what happens to the remaining cytoplasm and organelles (residual body)
removed by sertoli cells via phagocytosis
62
X and Y chromosome transcription stops before meoitic divisions T/F
T
63
when does autosomal transcriptional activity stop
during spermiogenesis
64
germ cell development is dependent on support from
somatic cells - specifically the nurse cells
65
what is transported through sertoli cells to germ cell
all nutrients
66
before the final maturation steps the sertoli cells play a role in what
cytoplasmic remodelling and release
67
when do spermatogonium become spermatocytes
once they enter meiosis and move away from the basement membrane. They cross into the adluminal compartment where they receive all nutrients from Sertoli cells
68
why do you need different parts of the seminiferous tubules out of sync
so you have sperm reaching maturity everyday
69
what cells regulate spermatogenesis
sertoli cells
70
gap junctions between adjacent sertoli cells provides means for...
communication
71
testosterone has 3 main functions in sertoli cells. these are:
- maintains integrity of blood testis barrier
- required for sertoli-spermatid adhesion
- essential for spermiation
72
androgens act autocrinology on leydig cells themselves in a ..... feedback loop
negative
73
testosterone is converted within the sertoli cells to dihydrotestosterone and ...
oestrogen
74
FSH acts on
sertoli cells
75
LH acts on ... cells. responsible for primary production of androgens such as testosterone
leydig
76
androgens act on the same cells that produce it - the ..... cells
leydig
77
testosterone travels to the seminiferous tubule lumen where it binds to .... produced by the sertoli cells
androgen binding proteins
78
testosteron-ABP travels ad stimulates the what?
ducts
79
testosterone and oestrogen have roles in both males and females T/F
T
80
mature sperm are stored in the tail end of the epididymis ready for ejaculation via the ......
vas deferens
81
what is oogenesis
the production of oocytes from primordial germ cells
82
where are oocytes produced
ovary
83
what does the ovarian stroma consist of
connective tissue, smooth muscle, stromal cells, developig follicles, interstitial glands
84
what are the uterine (fallopian) tubes important for
tranport of oocyte/embryo from ovaries to uterus
85
the female genital tract serves 2 main functions. these are:
- gamete production and transportation
| - site of implantation; support foetal development
86
what is the first half of the menstrual cycle referred to?
oestrogenic/follicular
87
what happens during the oestrogen/follicular half of the menstrual cycle
a mature oocyte is produced and made ready for fertilisation
88
what is the second half of the menstrual cycle referred to
progestagenic/luteal
89
what happens during the progestagenic/luteal phase of the menstrual cycle
uterus is made ready to allow implantation and support pregnancy
90
how does adult ovarian function differ from testicular function
- far fewer oocytes are produced (mitotic divisions only take place in foetal development)
- ovulation occurs episodically rather than continuously being produced
- ovulation stops at menopause
- oogenesis has start of meiosis then arrest at prophase 1
91
in the luteal phase what hormone dominates
progesterone
92
girls are born with primary oocytes arrestted when
prophase 1
93
resumption of meiosis and development of oocyte in females occurs after...
puberty
94
asymmetric divisions in oogenesis produce 1 mature oocyte and .... polar bodies that contain chromosomes but very little cytoplasmic material
2
95
after ovulation when fertilisation occur ..... is completed
meiosis 2
96
the follicle provides the appropriate supportive environment for a developing oocyte in the same way that the ............ support sperm development
seminiferous tubules
97
once you get ovulation, oocyte comes out of the follicle and the follicle becomes what
corpus luteum
98
oocyte secretes glycoproteins which condense to form what
zona pellucida
99
similarly to the sertoli cell in sperm development, there is contact between the oocyte and ....
granulosa cells
100
granulosa cells proliferate to form a thick layer around oocyte. contact between oocyte and granulosa cell is maintained through cytoplasmic processes
T
101
ovarian stromal cells condense to form....
thecal layer
102
the thecal cells expand and further develops to form 2 layer:
theca interna and theca externa
103
very early primordial follicle development is stimulated locally via growth factors and cytokines. further follicle development is dependent on
pituitary
104
absense of pituitary input to follicles results in
atresia (degeneration)
105
FSH-knockout mice arrest follicular development at .... stage
preantral
106
LH knockout mice stop follicular development at ... stage
antral
107
in response to FSH and LH stimulation, the follicles grow and eggs,,,,,
mature
108
as a result of LH stimulation. thecal cells produce what
androgens and testosterone
109
under the stimulation of FSH what do granulosa cells do
convert androgens produced by thecal cells to oestrogen
110
later in menstrual cycle, granulosa cells possess LH receptors and LH stimulation results in the synthesis of...
progesterone
111
oestrogens promote ... proliferation
granuloa
112
increasein androgens causes oestrogen surge. this then exerts a positive feedback to stimulate an .... surge
LH
113
the LH surge causes entry into the ......... phase of growth
preovulatory
114
within 2 hour of the start of the LH there is a transient rise (then decline) in the output f follicular oestrogens and androgens T/F
T
115
after ovulation, granulosa cells switch from oestrogen production to .......... production under LH stimulation
progesterone
116
after ovulation granulosa are stimulated by their own progesterone leading to an exponential increase in progesterone release that is characteristic of ...... phase
luteal
117
progesterone is essential for what to take place
ovulation
118
what doe the progesterone increase in the luteal phase do
depresses growth of less mature follicles, promotes transition to progestagenic phase of ovarian cycle
119
following ovulation the empty follicle collapses and becomes highly vascularised. it can now be referred to as the
corpus luteum
120
corpus luteum undergoes luteolysis. once corpus luteum is broken down you get what
the start of the new cycle
121
from the primary oocyte how many mature oocytes do you get
1
122
from one spermatocyte how many mature sperm do you get
4
123
sperm undergo maturation in the epididymis under the stimualtion by what
androgens
124
when sperm mature they acquire the ability to swim progressively. they have a more rigid flagellum and the ..... content of the tail increases
cAMP
125
when mature sperm enter the female tract they are not ready to fertlise. what do they have to undergo
capacitation
126
fully capacitated sperm exhibit 2 main characteristics. these are:
- hyperactivated motility
| - changes in membrane properties that subsequently allow the acrosome reaction to happen
127
why must sperm undergo capacitation
- to be more responsive to signals from oocyte
| - able to undergo the acrosome reaction which is essential for fertilisation
128
what is capacitation
- stripping or modification of surface glycoproteins
- changes in surface charge
- reduction in membrane stability through loss of cholesterol and formation of lipid rafts
129
how does capacitation occur
mechanisms not understood
130
for acrosome reaction you need capacitation but also need what
contact with the egg
131
the hyperactivated sperm motility caused by capacitation aids sperm peneatration of the what
zona pellucida
132
In humans ..% of spermatozoa do not even enter the cervix
99
133
oocyte and cumulus cells release what to aid sperm
chemoattractants
134
when does the acrosome reaction occur
after capacitation when the sperm head binds to the zona pellucida
135
what happens in the acrosome reation
1. sperm makes contact with egg
2. acrosome reacts with zona pellucida
3. acrosome reacts with perivitelline space
4. plasma membrane of sperm and egg fuse
5. sperm nucleus enters egg
6. cortical granules fuse with egg plasma membrane which renders the vitelline layer impenetrable to sperm
136
which part of the sperm enters egg
nucleus not the tail
137
the zona pellucida is composed of 4 main glycoproteins called
ZP1, ZP2, ZP3, ZP4
138
which zona pellucida protein is a structural protein which cross links to other zona proteins
ZP1
139
which zona protein contains sperm binding domain necessary for oocyte sperm recognition and penetration of zona pellucida. it is also responsible to the primary block to polyspermy
ZP2
140
which zona protein is involved with primary sperm egg binding
ZP3 complexed with ZP4
141
hyaluronidase from acrosome digests cumulus cells and exposes acrosin a proteiase on inner membrane of sperm triggering the ..... reaction
acrosome
142
following sperm/oocyte fusion what is released into the cytoplasm of the oocyte where it facilitates the hydrolysis of membrane bound PIP2 to DAG and IP3 triggering calcium release and oocyte activation
phospholipase C zeta
143
calcium pulses stimulate the resumption of what
meiosis
144
pronuclei come together, DNA replication occurs, pronuclear membranes break down and replicated chromosomes align on mitotic spindle ready for the first cleavage division
T
145
what is infertility
the inability to conceive within 1 year of trying (<35) or 6 months of trying (>35)
146
when men have a low sperm count what can this be referred to
oligozoospermia
147
low sperm mobility can be referred to as
asthenozoospermia
148
abnormal sperm can be referred to as
teratozoospermia
149
no sperm can be referred to as
azoospermia
150
ovulation problems can be caused by:
```
age
hormone imbalance
polycystic ovary syndrome
thyroid problems
premature ovarian failure
```
151
when was the first baby born by IVF
1978
152
what does IVF consist of
- ovarian hyperstimulation
- egg retrieval
- sperm preparation
- coincubation
- embryo transfer
153
sperm must be matured before IVD by the addition of appropriate factors that can stimulate ....
capacitation
154
when are oocytes collected in in vitro maturation
before final maturation step (follicles at antral stage)
155
during IVM oocytes are collected before maturation and are cultured in vitro in the presence of FSH prior to fertilisation using IVF. this means women can avoid the use of drugs which is expecially important for women with what condition
ovarian hyperstimulation syndrome (eg PCOS)
156
what is intra-cytoplasmic sperm injection (ICSI)
single sperm is injected directly into egg cytoplasm.
157
ICSI bypasses the normal events of fertilisation. sperm dont have to undergo what
capacitation
158
what is gamete intra-fallopian tube transfer (GIFT)
eggs and sperms combined in vitro and then inserted into fallopian tubes immediately. fertilisation happens inside body
159
what is zygote intra-fallopian transfer (ZIFT)
eggs and sperms are combined in vitro. wait until fertilisation occurs and embryo transferred into fallopian tubes
160
what is cryopreservation
freezing egg, sperm or embryo
161
what is mitochondrial supplementation to treat infertility called
cytoplasmic transfer
