female reproductive system 1/2 Flashcards
follicular phase of menstrual cycle
Begins with menstrual bleeding (menstruation), which marks the first day. Bleeding occurs after estrogen and progesterone levels decrease at the end of the previous cycle. This decrease causes the top layers of thickened lining of the uterus (endometrium) to break down/be shed.
About this time, FSH increases slightly, stimulating the development of several follicles in the ovaries. Each follicle contains an egg. Later, as FSH decreases, only one follicle continues to develop and produces estrogen .
in period, bleeding occurs after _______ levels ______
why?
estrogen and progesterone; decrease
this causes thickened endometrium to be shed
what stimulates the development of several follicles in the ovary in the follicular phase?
FSH slightly increases
ovulatory phase
second phase
begins with a surge in LH and FSH. LH stimulates egg release (ovulation), which usually occurs 16 to 32 hours after the surge begins. Estrogen peaks during the surge, and progesterone starts to increase.
luteal phase
third phase
LH and FSH decrease.
ruptured follicle forms a corpus luteum, which produces progesterone.
During most of this phase, the estrogen level is high. Progesterone and estrogen cause the uterus lining to thicken, preparing for possible fertilization.
If the egg is not fertilized, the corpus luteum degenerates and no longer produces progesterone, estrogen decreases, the top layers of the lining are shed, and menstrual bleeding occurs (the start of a new menstrual cycle).
surface epithelium of the ovary?
simple cuboidal mesothelium (germinal epithelium)
gonads arise from these 3 different sources:
Yolk sac (oocytes)
Coelomic epithelium (follicle cells)
Intermediate mesoderm
when des oogenesis begin?
4th fetal month
primordial germ cells are connected by ____ and proliferate by ____
intercellular bridges
mitosis
oogenesis by 5th fetal month
- oogonia stop undergoing mitosis; begin but DO NOT complete meiosis; enter state of dormancy. Primordial follicles form
at birth all oocytes are arrested in…
temporal? physical?
prophase of meiosis 1
they are in primordial follicles
pool of oocytes is ____ early in life
fixed
oogenesis and rate of atresia
- About 7 million oocytes at 5 months gestation
- Oocytes die and follicles degenerate:
- Oogonia not surrounded by follicular cells die
- Majority oocytes die in utero
- 700,000 to 2 million oocytes remain in ovaries at birth
- About 400,000 oocytes remain in ovaries at puberty
primordial ovarian follicle
- Cells quiescent, dormant
- Junctions between oocyte and follicle cells
- Follicle cells are squamous and sitting on a basement membrane
growing ovarian follicle
-
Zona pellucida
- Glycoprotein shell
- maintains sperm binding; also induces the acrosome reaction
- Zp is pierced by microvilli of oocyte and the filipodia follicular cells
- Contacted by gap junctions
-
Granulosa cells – secrete estrogen!
- Rest on a basement membrane
- Blood vessels do not pierce the basement membrane
vesicular ovarian follicle
- Fluid filled cavities form
- Fluid in cavities contains: hormones, growth factors, ions, proteoglycans, and oocyte maturation inhibitor
- Ovarian stroma is organized into:
- Theca interna – secretes androgen (estrogen precursor)
- Theca externa
mature graafian follicle
progression of follicle stages
primordial –> growing –> vesicular –> mature/graafian
puberty and the cyclic recruitment of follicles depends on….
FSH
ovarian follicular atresia
- Atresia can occur at any stage
- Oocyte dies –> Small follicles shrink and disappear –> Spontaneous death and resorption of cells
- Apoptosis of oocyte and granulosa cells
- Oocytes are gone by 51.3 years, start of menopause
- No germ cell renewal leads to reproductive senescence = menopause
in follicular atresia what hypertrophies and what sloughs?
THECA INTERNA HYPERTROPHIES AND THE GRANULOSA CELLS SLOUGH INTO THE ANTRUM
OVULATION
lh AND fsh SURGE right before ovulation
follicle ruptures
oocyte enters the uterine tube and completes meiosis 1 and arrests at metaphase 2
what surges before ovulation?
FSH and LH
what allows a follicle to rupture in ovulation?
- Increase in volume or pressure of follicular fluid
- enzymatic proteolysis of follicular wall and stroma of the ovary
- Hormones direct the deposit of GAGs
- PGs triggering contraction of SM fibers in the theca externa
after ovulation and before fertilization, where is the oocyte arrested?
metaphase meiosis 2
luteinization
- LH secretion induces formation of corpus luteum (yellow scar)
- Follicle collapses
- Blood then fibrin then CT invades follicular cavity
- Cells of granulosa and theca interna undergo gross, morphological changes
- Become granulosa lutein and theca lutein cells
- Cells increase in size and are filled with lipid droplets
- Cells secrete estrogen and progesterone (the broad surge during secretory phase)
- Rich vascular network forms within the corpus luteum
- Functional for about 14 days if no implantation of conceptus
what happens to corpus luteum if no fertilization and implantation occur?
corpus luteum degenerates; cell undergo apoptosis and and form a scar = the corpus albicans + levels of progesterone and estrogen decline
what cells secrete progesterone and estrogen in the corpus luteum?
foamy round granulosa lutein cells
function of corpus luteum
- It produces high levels of progesterone and estrogen which inhibit follicular development
- Its function declines after 8 weeks pregnancy and the placenta becomes the major source of estrogens and progesterone
- It persists throughout pregnancy and then degenerates after birth
role of uterine tubes (oviducts and fallopian tubes)
- Provides conduit to the uterus for the ova and a conduit to the ova for the sperm
- Sperm transport facilitated by peristaltic contractions by the muscularis
- Contractions of the muscularis are stimulated by PGs in the seminal fluid from the male and oxytocin from the pituitary of the female
- Provides environment for fertilization
what stimulates the muscularis contractions to move sperm up uterine tubes?
prostaglandins in the seminal fluid and oxytocin from the female pituitary
how long does conceptus remain in tubes?
- Conceptus remains in uterine tube for about 4 days after fertilization (last 2 cm of isthmus stays spastically contracted)
At about 4 days, increased progesterone levels cause muscle relaxation so conceptus can now enter uterus
conceptus undergoes what while it waits in the uterine tube?
- Conceptus undergoes cleavage in the uterine tube while it is delayed in its transport to the uterus
progression of oocyte after fertilization
oocyte –> 1 cell fertilized egg –> 2 cell (day 1)–> 4 cell (day 2)–> 8 cell (day 3) –> morula (day 4)–> blastocyst (day 5)
site of fertilization in the uterine tube?
ampulla
3 layers of uterine tube
describe the mucosal layer
mucosa, muscularis, and serosa
-
Mucosa – simple columnar epithelium with ciliated cells and secretory peg cells, with lamina propria
-
Ciliated cells – most numerous in the infundibulum and ampulla
- cilia beat TOWARD the uterus
- estrogen increases the number of ciliated cells and their activity
- axoneme (core) of the cilia is made of microtubules
- protein dynein is required for ciliary movement
-
Secretory peg cells – microvilli at apical surface
- Produce a uterine tube fluid that provides nutrients to oocyte, sperm and conceptus, promotes capacitation of sperm, protective against microorganisms, and increases volume in response to progesterone.
-
Ciliated cells – most numerous in the infundibulum and ampulla
how does wall structure change from the infundibulum to the uterine portion of uterine tubes?
- Decrease in mucosal infolding
- Increase in thickness of muscularis
- Increase in number of secretory epithelial cells
- Change in temperature (sperm are thermotactic)
endometrium
role and anatomy
- Proliferates and then degenerates during a menstrual cycle
- Vasculature also proliferates and degenerates during a menstrual cycle
- Divided: a functional layer and basal layer
- Functional layer has tubular glands; shed at menstruation
- Spinal artery is in functional layer
- Basal layer is not shed at menstruation; restores functional layer
- Functional layer has tubular glands; shed at menstruation
myometrium in pregnancy
- Grows in pregnancy à hypertrophy 50-500u and hyperplasia via myofiber division and mesenchymal cell differentiation
three phases of menstrual cycle
-
Menstrual
- Results from declining hormone levels
- Spinal arteries become ischemia, glands shrink, edema lessens, epithelium and vessels are disrupted, blood clotting is inhibited, and stratum functionale is shed!
-
Proliferative
- Under the influence of estrogen; follicles are maturing
- Basal layer of endometrium proliferates
- Epithelium reconstitutes glands
- Stroma – arteries lengthen, not very coiled and collagen + ground substance are secreted
-
Secretory
- Corpus luteum developing - Under influence of progesterone
- Endometrium increases thickness due to 3 sources: hypertrophy (mitoses rare), edema, and increased vascularity
placenta
role and components
- Functions: respiration, digestive, and urinary for fetus
Consists of 2 components:
- Fetal part of the placenta formed by the villous chorion
- Maternal part of the placenta derived from the endometrium – stratum functionalis becomes decidua basalis
how does the placenta develop?
- Trophoblast invasion: trophoblasts attach to the uterus wall and then proceed to invade the tissues of the uterus -They eventually reach deep into the wall and connect with the mother’s blood vessels. As the placenta continues to develop, a network is formed of finger-like projections, called villi, which project into spaces, or lacunae, that fill up with the mother’s blood.
- hypoxia stimulates the proliferation of cytotrophoblasts but not most other cells
- cytotrophoblasts plug the spinal arteries to help maintain state of hypoxia and cell proliferation
- at 10-12 weeks, blood flow into the intervillous space begins and cytotrophoblasts replace the maternal endothelial lining
- Normally cytotrophoblasts take on an endothelial phenotype
- Maternal spiral arteries are transformed into large caliber, low resistance vessels to provide adequate placental perfusion
what stimulates the cytotrophoblasts in placenta development?
hypoxia
hormones made by the placenta?
by whhat cells?
Hormones Made by the Placenta (syncytiotrophoblast)
- hCG
- progesterone
- estrogen
is there shedding or spinal arteries in the cervix?
NO, NEITHER!
in vaginal epithelium, what does estrogen promote?
- Estrogen promotes the synthesis and accumulation of glycogen
- Cells continually desquamated
- Estrogen à glycogen à lactobacilli vaginalis (main flora) use glycogen to make lactic acid à kills other species
mammary gland is a what?
- Modified apocrine sweat gland
suspensory ligaments in the breast?
coopers ligaments
inactive vs active mammary tissue
- Inactive mammary gland
- Sparse glandular component, mostly ducts
- Active mammary gland
- Secretory cell proliferation, duct branching, and appearance of alveoli
- Intra and inter lobular ducts
