Control of ovarian function and menstrual cycle Flashcards
1
Q
when do the early stages of gametogenesis occur in females
A
during development before birth
2
Q
females supply of oocytes is
A
limited
3
Q
male supply of gametes is
A
unlimited
4
Q
what controls female reproductive function after puberty
A
hormone cycle and interactions between the ovary and the hypothalamus and pituitary
5
Q
LH in females
A
control reproductive cycle and ovulation
stimulates oestrogen
6
Q
FSH in females
A
stimulates the growth and maturation of ovarian follicles
7
Q
what do ovarian follicles consist of
A
squamous follicular cells, oocyte and primordial follicle
8
Q
where are ovarian follicles
A
scattered throughout ovaries
9
Q
female reproductive cycle inolves two hormones
A
oestradiol and progesterone - both steroid hormones
10
Q
where are oestrogens synthesised
A
from androgens
11
Q
where are oestrogens released
A
ovaries
12
Q
primary oestrogen iin non-pregnant females
A
oestradiol
13
Q
what is progesterone
A
steroid hormone derived from same precursos as testosterone and oestrogen
14
Q
what does progesterone do
A
supports potential pregnancy - pro gestation
15
Q
what processes is prgesterone involved in
A
menstrual cycle
pregnancy
16
Q
ovary function
A
- oogenesis
- inactive primary ooctye to ovulation
- menstrual cycle
- fertilisation and implantation
17
Q
when does oogenesis start
A
before birth
18
Q
first cells of oogenesis
A
migratory germ cells; diploid
19
Q
what happens to migratory germ cells and when
A
divide by mitosis to produce oogonia
starts from 4-8 weeks of foetal development
20
Q
what happens to oogonia and when
A
divide by asymmetric mitosis to produce one oognoia and one primary ooctye
starts from week 10-20 of foetal development
21
Q
dna content of oogonia
A
diploid, 46
22
Q
what happens to oogonia after birth
A
dissappear from ovaries
23
Q
dna content of primary oocyte
A
diploid; 46
24
Q
what happens to primary oocytes
A
start meiosis but stop at prophase I and become dormant in uterus until adulthood
25
what stage of meiosis are primary ooctyes halted
prophase I
26
what happens to primary oocytes halted at prophase I
remain dormant in uterus until adulthood
27
when are primary ooctyes numbers highest
before birth
28
why do primary ooctyes reduce in numbers after birth
process of selection; only the best oocytes will survive until after puberty
29
when are primary ooctye levels too low to maintain reproductive function
post menopause
30
development of follicle in inital recruitment
- primordial follicle
- primary follicle
- secondary/antral follice
ovarian cycle
- mature follicle
31
what happens to antral follicle
enters the ovarian cycle becuase can no longer develop without stimulus
32
size of primordial follicle
40 um
33
size of primary follicle
100 um
34
size of antral follicle
200-400um
35
primordial follicle
immature dormant oocyte, surrounded by flat granulosa cells
36
primary follicle
- oocyte genome activates, causing gene transcription signalling between oocye and follicle
- granulosa cells change from flat to cuboidal
- zona pellucida forms around oocyte
- follicle develops FSH receptors
37
when does zona pellucida form around oocyte
primary follicle during initial recruitment
38
when does follicle develop FSH receptors
primary follicle during inital recruitment
39
antral follicle
- theca cells recruited to form basal lamina around follicle
- antrum forms next to oocyte
- 300 days after inital recruitment
40
what is an antrum
fluid filled cavity next to oocyte, formed 300 days after intial recruitment when antral follicle has formed
41
what happens to basal lamina around antral follicle
differentiates to two layers
- theca externa
- theca interna
provides blood supply to follicle
42
what provides antral follicle with blood supply
basal lamina that's differentiated into two layers
43
size of mature follicle
20mm
44
what causes mature follicle
follicular phase of ovarian cycle
45
what does mature follicle do
- FSH stimulates growth of follicle and releases inhibin from granulosa
- follicles compete for FSH
- continues until only one dominant follicle remains
46
selection process of mature follicles
they compete for FSH which causes weaker follicles to be destroyed, until only one dominant follicle remains
47
phases of the ovarian cycle
- follicular phase
- ovulatory phase
- luteal phase
48
when is the follicular phase
day 1-10
49
when is the ovulatory phase of the menstrual cycle
day 11-14
50
when is the luteal phase
day 14-18
51
follicular phase
hormonal signals cause 10-20 follicles to grow
| one oocyte is selected, remainder become atretic
52
ovulatory phase of ovarian cycle
oocyte undergoes cell division
follicle walls thin & rupture
oocyte released from ovary and enters abdominal cavity near fimbrae of fallopian tube
53
luteal phase
progesterone increases
egg travles through fallopian tube toward uterus
theca cells become small luteal cells
granulosa cells become large luteal cells
54
what happens to theca cells in the luteal phase
become small luteal cells which produce androgens and progesterone
55
what happens to graulosa cells in luteal phase
become large luteal cells which produce oestrogen and progesterone
56
why does the antral folllicles enter the ovarian cycle
needs hormonal stimulation to grow
57
follicuar phase, hormone
- antral follicles dependent on FSH to grow
- FSH high from previous cycle
- LH stimulates theca cells to produce androgens
- granulosa convert androgens to oestradiol
- as follicle grows, oestradiol increases
58
when do antral follicles become dependent on FSH
follicular phase
59
what does LH do to theca cells
stumlates production of androgens
60
what converts androgens to oestradiol
granulosa
61
ovulatory phase, hormones
- high concentrations of oestradiol has +ve effect on LH
- LH surge
- ovulation occurs which is the release of oocyte into fallopian tube
62
oestradiol and its effects on LH
- normally has negative effects
| - in ovulatory phase oestradiol levels are high enough that they have a postive effect and cause and LH surge
63
what causes LH surge
high oestradiol
64
what causes ovulation
LH surge
65
what is ovulation
release of oocyte into fallopian tube
66
luteal phase, hormones
- follicle collapses because oocyte released
- corpus luteum forms
- corpus luteum releases oestradiol and progesterone
- corpus luteum degenerates after 14 days of no fertilisation
- progesterone and oestradiol levels drop which removes negative effect on FSH
- FSH levels increase to restart cycle
67
what is corpus luteum
collapse of follicle after ovulation
68
what does corpus luteum release
oestradiol and progesterone
69
how longe does corpus luteum survive
14 days if no fertilisation
70
what do progesterone and oestradiol inhibit
FSH
71
How does ovarian cycle restart
when corpus luteum degenerates, oestradiol and progesterone levels drop which means FSH is no longer inhibited
72
when does ooctye continue meiosis
just before ovulation, day 11-14
73
what happens to oocyte during ovulation
just before oculation, oocyte completes meiosis I to form one secondary oocyte and one polar body
74
dna content of secondary oocyte
haploid, 23
75
what is a polar body
the remianing DNA of primary ooctyre after meiosis I,
76
what happens to polar body
degenerates
77
what happens to secondary oocyte during ovualtion
immediatetly starts meiosis II but stops at metaphase II
78
what stops at metaphase II of meiosis II
secondary oocyte
79
what causes proliferation of granulosa cells in follicular phase
FSH
80
why does oestradiol increase in follicular phase
becuase follicle grows
81
what causes FSH to drop in follicular phase
negative feedback
82
what controls the ovarian cycle
HPG-axis
83
how is LH inhibited in luteal phase
oestradiol levels fall because of follicle collapse and so they resume their negative effects
84
purpose of menstrual cycle
prepare for possible fertilisation
85
what is the menstrual cycle
series of changes in the endometrium in response to changing hormone lvels
86
stages of menstrual cycle
- proliferative phase
- late proliferative phase
- secretory phase
- late secretory phase
- menstrual phase
87
when is the proliferative phase
day 5-13
88
when is the late proliferative phase
day 13-14
89
when is the secretory phase
day 15-22 // week 3
90
when is the late secretory phase
day 23-28
91
when is the menstrual phase
day 1-5
92
proliferative phase
- endometrium proliferates and thickens
- tubular glands and arteries form
- stimulation of pregesterone receptor synthesis in endometrial cells
93
late proliferative phase
glands are long and tortuous due to active growth
| stroma gradully become oedematous
94
secretory phase
endometrium becomes dependent on progesterone from corpus luteum
tubular glands enlarge and secrete mucus and glycogen to prepare for implantation of fertilised ovum
95
what do tubular glands secrete in preparation of implantaton
mucus and glycogen
96
why are mucus and glycogen secreted from tubular glands of the endometrium
to prepare for implantatium of fertilised ovum
97
late secretory phase, no fertilisation
- corpus luteum degernates
- progesterone levels drop
- endometrium degenerates
- uterine glands are wide
- arteries begin contracting
- capilary beds begin leaking blood into endometrium and uterus
98
menstrual phase
- uterine lining sloughs off and is removed from body
| once removed, endometrium will begin to proliferate again
99
what happens if fertilisation occurs
acrosome reaction and implantation
100
what happens to the secondary oocyte during fertilisatio
completes meiosis II to form oocyte and polar body
101
when does secondary ooctye complete meiosis II
fertilisation
102
what happens during fertilsation
sperm cell chromosomes fuse with oocyte to form diploid zygote, 46
103
DNA content of zygote
diploid, 46
104
what is a zygote
sperm cell fused with oocyte
105
what happens to zygote once formed
starts to divide and travel along fallopian tube for 4 days
106
what happens on day 5 of the zygote
zygote reaches uterus and becomes a blastocyst
107
when does blastocyst form
whe the zygote reaches the uterus after 5 days
108
what is a blastocyst
inner cell mass formed from a zygote that will become the embryo
109
what is a trophoblast
surrounds the inner cell mass of blastocyte and will become placenta
110
what does placenta develop from
trophoblast
111
implantation
trophoblast attatches to surface of endometrium by invading the endometrium
112
what do trophoblasts produce and why
human chorionic gonadotropin to maintain the corpus luteum in early pregnancy
113
what does human chorionic gonadotropin do
maintains the corpus luteum in early pregnancy
114
where is human chorionic gonadotropin released from
trophoblast
115
what is the effect of maintaining corpus luteum in early pregnancy
endometrium isn't shed and progesteron is still produced
116
at what level do distrubances in ovarian function occur
genetic
hypothalamic
pituitary
target tissue
117
genetic level disturbances of ovarian function
Turner syndrome
| triple X
118
triple X
genetic disturbance to ovarian function
119
Turner syndrome
genetic disturbance to ovarian function, only one X chromosome
120
what is triple X
female has XXX chromosomes
121
effects of Triple X
vary, some show no symptons.
can cause under developed ovaries and reduced fertility
other health problems e.g web of skin on neck, constricted aorta, poor breast development,
122
what is turner syndrome
when femal only has one X chromosome
123
effects of turner syndrome
most embryos will spontaneously abort or be still born
non-functional ovaries and lack of reproductive function
causes many health problems e.g short, low hairline, elbow deformity, constricted aorta, small fingernails, widely spaced nipples, brown spots
124
hypothalamic level disturbances to ovarian function
Kallman syndrome
125
kallman syndrome
hypothalamic level disturbance to ovaries or testes
126
symptoms of Kallman
same in male as female
127
pituitary level disturbances to ovarian function
hyperprolactinaemia
128
hyperprolactinaemia
pituitary level disturbances to ovary or teste function
129
symptoms of hyperprolactinaemia
same in male as female
130
ovary level disturbances to ovary function
PCOS polycystic ovarian syndrome
131
PCOS polycystic ovarian syndrome
ovary level disturbances to ovary function
132
what causes PCOS
unclear but possible genetic
133
what is PCOS
when some antral follicles halt development and release exessive androgens
134
effects of PCOS
vary, can cause hirustism and makes susceptbiel to other diseases like diabetes
135
prevalence of PCOS
affects 5-10% of females; most common femal endocrine disorder
136
other tissues disturbances that efect ovarian function
congenital adrenal hyperplasia
137
what causes congenital adrenal hyperplasia
mutation leading to inactivation of enzyme responsible for cortisol synthesis so adrenal gladn cannot produce cortisol and instead produces excess androgens
138
enzyme reponsible for cortisol synthesis
21-hydroxylase
139
effects of congenital adrenal hyperplasia
excess androgens causes development of male external genitalia. can still have normal uterus and ovarias becuase genetically female.
