Female reproductive processes Flashcards
week 4
what are three difefrences between spermogenesis and oogenesis?
life limit (F= limited, M-limited)
continunity (F= interrupted meiosis, M= continious meiosus)
division (F= asymmetric division (1) M= symmertical (4)
Describe the role of Cohesins in Meiotic arrestand increasubf tisk of down syndrome
they keep sister chromatids together
Weaken with increase in maternal age
= incorrect microtubule=centromere attachment
= chromosome segregation erros (nondisjunction) in metapahse and anaphase I
What is the first follicle of Follicle development? Structure?
Primordial follicle
Oocyte surrounded by single layer of ill-defined squamous-like follicle cells
What is the second follicle of Follicle development and how is it formed?
primary follicle
Differentiation –> single layer of cuboidal/ columnar type follicle cells surrounding oocyte
What is the third follicle of Follicle development? Structure?
Secondary follicle
Two or more layers of stratified granulosa cells surround oocyte
What is the fourth follicle of Follicle development? Structure?
Late secondary follicle
Fluid-filled spaces between granulosa cells appear
Thecal cells and zona become visible
What is the fifth follicle of Follicle development? Structure?
Tertiary follicle
Central fluid filled cavity forms
Corona radiata (cumulus cells) Ooccyte
What is the sixth follicle of Follicle development? Structure?
ovulating follicle
Follicle ruptures
Oocyte ovulated with cumulus cells
How is the seventh element of follicle development formed and what is its function?
Corpus luteum
Residual follicle forms corpus luteum
Secretes hormones that maintain pregnancy
What is the 8th step of follicle development?
Corpora albicantia
Widespread cell death
Leaves scar tissues
What are the hormones involved in the Ovarian cycle and what are their functions?
GnRH: release of LH and FSH
LH: stimulates secretion of androgens
FSH: supports conversion of androgens –> estrogens
Osetrogen: negatively/pos regulation of GnRH, LH and FSH. Stimulates endometrium and pri/sec sex characteristics.
Inhibin: inhibits FSH
Progesterone: negative regulation of GnRH, LH and FSH, Stimulates endometrium and pri/sec sex characteristics.
What are the two main phases of the ovarian cycle and when do they occur?
Folllicular (1-14)
Luteal (15-28)
What occurs in the follicular stage before puberty?
primordial follicles spontaneously activate
What are the steps in oogensis?
- oogonium → primary oocytes (before birth) by mitosis
- primary oocyte arrested in prophase I
- completes meiosis I in response to LH surge → secondary oocyte and 1st polar body
- secondary oocyte is arrested in metaphase II
- ovulation of the secondary oocyte
- completes meiosis II in response to fertilisation → ovum and 2nd polar body
What occurs in the follicular phase after puberty? What are the changes in hormones?
growth of secondary follicles accelerated by FSH and LH
Growth follicles (due to increase estrogen/inhibin and decrease in FSH)
What are the preantral and antral follicle types?
preantral
= Primordial follicle, primary follicle, secondary follicle and late secondary follicle
antral
= tertiary antral and Graafian (amture vesicualr follicle)
In a regular cycle, when does ovulation occur?
14 dats after mensturation
Hormones of ovulation
Elevated estrogen = forms dominant follicle
Triggers LH surge = resumes meiosis in metaphase II, final growth of follcile wall and ovulation.
afterwards: oestrgen declines
What are the three layers of the uterus and their function?
Perimetrium
Myometrium – bulky contractile smooth muscle
Endometrium- startum functionalis (sheds) and stratum basalis (rebuilds finctional layer)
What is the function of the uterine cycle and how long does it take?
prepare uterus to receive fertilized embryo after ovulation.
average = 29.5 days
shorter as age
what are the three phases of the uterine cycle and when do they occur?
Menstrual
Days 1-5
Proliferative
6-14
Secretory
15-28
What occurs in each of the three phases of the uterine cycle?
Menstrual – destructive phase
-Shedding of functional endometrium layer
Proliferative – follicular, oestrogenic
-Rebuilding functional layer
Secretory – luteal, pregestational
-Enrichment of blood supply and nutrient secretion of endometrial glands
Describe the events of the shedding of the functional endometrium.
Uterine arteries extend branches into uterine wall
Arcuate arteries of myometrium send branches into endometrium= straight arteries in basal, spiral in functional.
Degenerating functional layer fragments and sloughs off.
Is there more progestrone or estrogen in the luteal phase and what is the impact of this?
Luteinized granulosa cells secretes more progesterone than estrogen = decrease in FSH and LH = pause on folliculogenesis
progesterone = dominant – singles ovulation occurs and makes endometrium receptive to implantation.
Steps of luteal phase
Ovulation ends
LH stimulates granulosa and theca cells differentiate into large and small luteal cells (respectively) = corpus luteum
Luteinized granulosa cells secretes more progesterone than estrogen = decrease in FSH and LH = pause on folliculogenesis.
Inhibin also inhibits FSH
Estrogen declines and progesterone = dominant – singles ovulation occurs and makes endometrium receptive to implantation.
compare CL in pregnant and non-pregnant cycles.
Non-Pregnant Cycle: The corpus luteum degenerates if pregnancy does not occur, leading to a decrease in progesterone and estrogen and the start of menstruation. LH initally supports it.
Pregnant Cycle: The corpus luteum is maintained by hCG and continues to produce PE and E to maintain endometrial lining.
compare the ovarian cycle w the uterine cycle
The ovarian cycle = changes that occur in the follicles of the ovary,
uterine cycle = changes in the endometrial lining of the uterus.
ovarian
-follicular and luteal
uterine
-menstural
-prolifertive
-secretory
