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human reproduction and fertility > jones > Flashcards

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

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2
Q

where do endocrine glands secrete hormones

A

into the bloodstream; the hormones travel to and act on other organs or tissues

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3
Q

what is the hypothalamus

A

part of the forebeain that regulates core (homeostatic) functions eg metabolism, growth, reproduction and stress

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4
Q

what is a critical component of the reproductive system that is secreted for the hypothalamus

A

peptide hormone gonadotrophin releasing hormone (GnRH)

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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

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6
Q

gonadotroph proliferation and hormone production is positively regulated by signalling through a what

A

G-protein coupled receptor GnRHr

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7
Q

activation of G-protein coupled receptor causes gonadotrophs to secrete

A

FSH and LH

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8
Q

there are 3 main types of sex steroid. these are..

A

progesterones, androgens and oestrogen

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9
Q

all sex steroids are derived from which common precursor

A

cholesterol

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10
Q

once inside a cell, steroid-receptor complexes bind to steroid response elements on DNA and impact on transcription

A

T

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11
Q

what does oestrogen bind

A

oestrogen receptor on the gonadotroph

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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

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13
Q

binding of oestrogen to the oestrogen receptor on the gonadotroph leads to the reduction of what

A

production of FSH and LH

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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

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15
Q

feedback control happens at the level of what

A

pituitary, hypothalamus or testes and ovaries

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16
Q

LH and FSH output is predominantly regulated by secretory products of which female organ

A

ovary

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17
Q

which secretory products from ovary exert a depressent effect on gonadotrophin output (FSH and LH)

A

oestrogens, progesterones and inhibins

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18
Q

which secretory products from ovary cause a surge on gonadotrophin output (FSH and LH)

A

activin, oestradiol

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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

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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

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21
Q

inhibins selectively negatively regulate … secretion

A

FSH

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22
Q

what cells does FSH act on

A

granulosa cells

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23
Q

what cells does LH act on

A

thecal cells

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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)

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25
Q

which cells secrete androgens (mainly testosterone)

A

leydig cells

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26
Q

leydig cells secrete androgens that exerts a negative feedback response which causes a decrease in ….

A

GnRH

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27
Q

as in females, what acts at the level of the pituitary to supress FSH secretion

A

inhibin

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28
Q

GnRH is essential for gonadal function. when there is destruction of GnRH neurons what happens

A

gonadal atrophy

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29
Q

when do GnRH pulses begin

A

puberty

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30
Q

what are the 2 ways in which alterations of the output of LH and FSH can be achieved

A
  • increasing or decreasing the amplitude or frequency of GnRH pulses
  • modulating the response of gonadotrophs to the pulses
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31
Q

kisspeptin 1 is a 54 amino acid neuropeptide that binds to which receptor on GnRH neurons

A

GPR54

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32
Q

kisspeptin is a potent GnRH stimulator T/F

A

T

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33
Q

binding to oestrogen to kiss1 positie neurons results in…

A

negative feedback by decreasing GnRH expression

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34
Q

leptin is a peptide hormone produced by…

A

adipocytes

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35
Q

leptin levels relate to … levels

A

fat

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36
Q

leptin may be involved in activating the HPG axis at puberty via…

A

KISS1

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37
Q

leptin is necessary for what to proceed

A

puberty

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38
Q

what is spermatogenesis

A

the production of spermatozoa from spermatogonial stem cells

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39
Q

the testes are the site of spermatogenesis. what do the testes house

A

seminiferous tubules

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40
Q

what is the epididymis the site of

A

sperm storage and maturation

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41
Q

what is the vas deferens important for

A

transport of sperm from epididymis dueing ejaculation

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42
Q

what does the seminal vesicle produce

A

mucus secretion which aids mobility of sperm

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43
Q

what does the prostate gland produce

A

an alkaline secretion that neutralises acidity of any urine in urethra

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44
Q

what is the urethra

A

a tube that carries urine and sperm out of the body

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45
Q

the testis have 2 main overlapping functions

A
  • produce androgens foe sexual differentiation

- to produce spermatozoa for sexual reproduction

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46
Q

testes have stroma consisting of blood vessels, lymph and leydig cells. what do leydig cells synthesise and secrete

A

steroid hormones

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47
Q

what are primordial germ cells

A

gamete precursors

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48
Q
  • The PGC population expands by mitosis and migrates to the genital ridge primordium by 6 weeks gestation
A

T

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49
Q

the germinal epithelium eventually bcomes which 2 types of cells

A 
sertoli cells (male)
granulosa cells (female)
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50
Q

when does spermatogenesis begin and how many sperm are produced perday

A

begins at puberty

about 100 million sperm produced per day

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51
Q

what is the final differentiation step in spermatogenesis called

A

spermiogenesis

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52
Q

spermatogenesis involves mitosis and meiosis T/F

A

T

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53
Q

how many mature spermatozoa does spermatogenesis produce

A

4

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54
Q

what happens in spermatogenesis

A

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

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55
Q

what are spermatogonial stem cells

A

self regenerating pool which undergo rounds of mitosis

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56
Q

where is it determined whether spermatogonia will divide or differentiate?

A

seminiferous tubules

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57
Q

immature sperm cells are attached to sertoli cells. where do they move when they differentiate

A

lumen of seminiferous tubules

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58
Q

what happens in spermiation

A

cytoplasmic bridges are broken and fully differentiated sperm are released into lumen

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59
Q

what part of sperm is important for fertilisation

A

acrosome cap

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60
Q

the mid piece of sperm contains the…

A

mitochondria

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61
Q

when a spermatid develops into a mature spermatozoa, what happens to the remaining cytoplasm and organelles (residual body)

A

removed by sertoli cells via phagocytosis

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62
Q

X and Y chromosome transcription stops before meoitic divisions T/F

A

T

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63
Q

when does autosomal transcriptional activity stop

A

during spermiogenesis

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64
Q

germ cell development is dependent on support from

A

somatic cells - specifically the nurse cells

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65
Q

what is transported through sertoli cells to germ cell

A

all nutrients

66
Q

before the final maturation steps the sertoli cells play a role in what

A

cytoplasmic remodelling and release

67
Q

when do spermatogonium become spermatocytes

A

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
Q

why do you need different parts of the seminiferous tubules out of sync

A

so you have sperm reaching maturity everyday

69
Q

what cells regulate spermatogenesis

A

sertoli cells

70
Q

gap junctions between adjacent sertoli cells provides means for…

A

communication

71
Q

testosterone has 3 main functions in sertoli cells. these are:

A
  • maintains integrity of blood testis barrier
  • required for sertoli-spermatid adhesion
  • essential for spermiation
72
Q

androgens act autocrinology on leydig cells themselves in a ….. feedback loop

A

negative

73
Q

testosterone is converted within the sertoli cells to dihydrotestosterone and …

A

oestrogen

74
Q

FSH acts on

A

sertoli cells

75
Q

LH acts on … cells. responsible for primary production of androgens such as testosterone

A

leydig

76
Q

androgens act on the same cells that produce it - the ….. cells

A

leydig

77
Q

testosterone travels to the seminiferous tubule lumen where it binds to …. produced by the sertoli cells

A

androgen binding proteins

78
Q

testosteron-ABP travels ad stimulates the what?

A

ducts

79
Q

testosterone and oestrogen have roles in both males and females T/F

A

T

80
Q

mature sperm are stored in the tail end of the epididymis ready for ejaculation via the ……

A

vas deferens

81
Q

what is oogenesis

A

the production of oocytes from primordial germ cells

82
Q

where are oocytes produced

A

ovary

83
Q

what does the ovarian stroma consist of

A

connective tissue, smooth muscle, stromal cells, developig follicles, interstitial glands

84
Q

what are the uterine (fallopian) tubes important for

A

tranport of oocyte/embryo from ovaries to uterus

85
Q

the female genital tract serves 2 main functions. these are:

A
  • gamete production and transportation

- site of implantation; support foetal development

86
Q

what is the first half of the menstrual cycle referred to?

A

oestrogenic/follicular

87
Q

what happens during the oestrogen/follicular half of the menstrual cycle

A

a mature oocyte is produced and made ready for fertilisation

88
Q

what is the second half of the menstrual cycle referred to

A

progestagenic/luteal

89
Q

what happens during the progestagenic/luteal phase of the menstrual cycle

A

uterus is made ready to allow implantation and support pregnancy

90
Q

how does adult ovarian function differ from testicular function

A
  • 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
Q

in the luteal phase what hormone dominates

A

progesterone

92
Q

girls are born with primary oocytes arrestted when

A

prophase 1

93
Q

resumption of meiosis and development of oocyte in females occurs after…

A

puberty

94
Q

asymmetric divisions in oogenesis produce 1 mature oocyte and …. polar bodies that contain chromosomes but very little cytoplasmic material

A

2

95
Q

after ovulation when fertilisation occur ….. is completed

A

meiosis 2

96
Q

the follicle provides the appropriate supportive environment for a developing oocyte in the same way that the ………… support sperm development

A

seminiferous tubules

97
Q

once you get ovulation, oocyte comes out of the follicle and the follicle becomes what

A

corpus luteum

98
Q

oocyte secretes glycoproteins which condense to form what

A

zona pellucida

99
Q

similarly to the sertoli cell in sperm development, there is contact between the oocyte and ….

A

granulosa cells

100
Q

granulosa cells proliferate to form a thick layer around oocyte. contact between oocyte and granulosa cell is maintained through cytoplasmic processes

A

T

101
Q

ovarian stromal cells condense to form….

A

thecal layer

102
Q

the thecal cells expand and further develops to form 2 layer:

A

theca interna and theca externa

103
Q

very early primordial follicle development is stimulated locally via growth factors and cytokines. further follicle development is dependent on

A

pituitary

104
Q

absense of pituitary input to follicles results in

A

atresia (degeneration)

105
Q

FSH-knockout mice arrest follicular development at …. stage

A

preantral

106
Q

LH knockout mice stop follicular development at … stage

A

antral

107
Q

in response to FSH and LH stimulation, the follicles grow and eggs,,,,,

A

mature

108
Q

as a result of LH stimulation. thecal cells produce what

A

androgens and testosterone

109
Q

under the stimulation of FSH what do granulosa cells do

A

convert androgens produced by thecal cells to oestrogen

110
Q

later in menstrual cycle, granulosa cells possess LH receptors and LH stimulation results in the synthesis of…

A

progesterone

111
Q

oestrogens promote … proliferation

A

granuloa

112
Q

increasein androgens causes oestrogen surge. this then exerts a positive feedback to stimulate an …. surge

A

LH

113
Q

the LH surge causes entry into the ……… phase of growth

A

preovulatory

114
Q

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

A

T

115
Q

after ovulation, granulosa cells switch from oestrogen production to ………. production under LH stimulation

A

progesterone

116
Q

after ovulation granulosa are stimulated by their own progesterone leading to an exponential increase in progesterone release that is characteristic of …… phase

A

luteal

117
Q

progesterone is essential for what to take place

A

ovulation

118
Q

what doe the progesterone increase in the luteal phase do

A

depresses growth of less mature follicles, promotes transition to progestagenic phase of ovarian cycle

119
Q

following ovulation the empty follicle collapses and becomes highly vascularised. it can now be referred to as the

A

corpus luteum

120
Q

corpus luteum undergoes luteolysis. once corpus luteum is broken down you get what

A

the start of the new cycle

121
Q

from the primary oocyte how many mature oocytes do you get

A

1

122
Q

from one spermatocyte how many mature sperm do you get

A

4

123
Q

sperm undergo maturation in the epididymis under the stimualtion by what

A

androgens

124
Q

when sperm mature they acquire the ability to swim progressively. they have a more rigid flagellum and the ….. content of the tail increases

A

cAMP

125
Q

when mature sperm enter the female tract they are not ready to fertlise. what do they have to undergo

A

capacitation

126
Q

fully capacitated sperm exhibit 2 main characteristics. these are:

A
  • hyperactivated motility

- changes in membrane properties that subsequently allow the acrosome reaction to happen

127
Q

why must sperm undergo capacitation

A
  • to be more responsive to signals from oocyte

- able to undergo the acrosome reaction which is essential for fertilisation

128
Q

what is capacitation

A
  • stripping or modification of surface glycoproteins
  • changes in surface charge
  • reduction in membrane stability through loss of cholesterol and formation of lipid rafts
129
Q

how does capacitation occur

A

mechanisms not understood

130
Q

for acrosome reaction you need capacitation but also need what

A

contact with the egg

131
Q

the hyperactivated sperm motility caused by capacitation aids sperm peneatration of the what

A

zona pellucida

132
Q

In humans ..% of spermatozoa do not even enter the cervix

A

99

133
Q

oocyte and cumulus cells release what to aid sperm

A

chemoattractants

134
Q

when does the acrosome reaction occur

A

after capacitation when the sperm head binds to the zona pellucida

135
Q

what happens in the acrosome reation

A
  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
Q

which part of the sperm enters egg

A

nucleus not the tail

137
Q

the zona pellucida is composed of 4 main glycoproteins called

A

ZP1, ZP2, ZP3, ZP4

138
Q

which zona pellucida protein is a structural protein which cross links to other zona proteins

A

ZP1

139
Q

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

A

ZP2

140
Q

which zona protein is involved with primary sperm egg binding

A

ZP3 complexed with ZP4

141
Q

hyaluronidase from acrosome digests cumulus cells and exposes acrosin a proteiase on inner membrane of sperm triggering the ….. reaction

A

acrosome

142
Q

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

A

phospholipase C zeta

143
Q

calcium pulses stimulate the resumption of what

A

meiosis

144
Q

pronuclei come together, DNA replication occurs, pronuclear membranes break down and replicated chromosomes align on mitotic spindle ready for the first cleavage division

A

T

145
Q

what is infertility

A

the inability to conceive within 1 year of trying (<35) or 6 months of trying (>35)

146
Q

when men have a low sperm count what can this be referred to

A

oligozoospermia

147
Q

low sperm mobility can be referred to as

A

asthenozoospermia

148
Q

abnormal sperm can be referred to as

A

teratozoospermia

149
Q

no sperm can be referred to as

A

azoospermia

150
Q

ovulation problems can be caused by:

A 
age
hormone imbalance
polycystic ovary syndrome
thyroid problems
premature ovarian failure
151
Q

when was the first baby born by IVF

A

1978

152
Q

what does IVF consist of

A
  • ovarian hyperstimulation
  • egg retrieval
  • sperm preparation
  • coincubation
  • embryo transfer
153
Q

sperm must be matured before IVD by the addition of appropriate factors that can stimulate ….

A

capacitation

154
Q

when are oocytes collected in in vitro maturation

A

before final maturation step (follicles at antral stage)

155
Q

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

A

ovarian hyperstimulation syndrome (eg PCOS)

156
Q

what is intra-cytoplasmic sperm injection (ICSI)

A

single sperm is injected directly into egg cytoplasm.

157
Q

ICSI bypasses the normal events of fertilisation. sperm dont have to undergo what

A

capacitation

158
Q

what is gamete intra-fallopian tube transfer (GIFT)

A

eggs and sperms combined in vitro and then inserted into fallopian tubes immediately. fertilisation happens inside body

159
Q

what is zygote intra-fallopian transfer (ZIFT)

A

eggs and sperms are combined in vitro. wait until fertilisation occurs and embryo transferred into fallopian tubes

160
Q

what is cryopreservation

A

freezing egg, sperm or embryo

161
Q

what is mitochondrial supplementation to treat infertility called

A

cytoplasmic transfer

human reproduction and fertility (3 decks)

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