Female Reproductive System Flashcards
Mons pubis
Cushion of fatty tissue over pubic symphysis-covered by skin and pubic hair.
- many touch receptors, few pressure receptors
- distribution/amount of public hair differs
Labia majora
Major lips-homologous with scrotum
- large fatty skin folds covered with hair, sweat, and oil glands
- few touch or pressure receptors
Labia minors
Minor lips-homologous to prelude of penis.
- thin skin folds covering vaginal+urethra opening in unstimulated condition
- oil but no sweat glands or hair (secreted smegma)
- few touch/ pressure receptors
What forms the boundary of the vestibule
Labia minora
Vestibule
Contains the opening of the vagina (vaginal introitus) and the urethral orifice (meatus or urethral opening). Also an opening for glands.
Paired lesser Vestibule glands
Below either side of urethral orifice are the openings of two small ducts leading to the paired lesser vestibular glands (skene’s glands)
- secrete a small amount of fluid for lubrications and or anti microbial
- homologous to prostate gland
Greater vestibular glands
Near the bottom to each side of the introitus (bartholins glands)
- secrete mucus for lubrications
- homologous to bulbourethral gland
Clitoris
- the glans clitoris is a small visible portion of the clitoris (1-1.5cm long and 0.5cm in diameter)
- just above the junction of the labia minora
- highly innervated erectile tissue, homologous to glans penis.
- covered by a good/head of skin called the prepuce (like male)
The clitoris has an internal anatomy consisting of 4 main areas…
Body, crus, root, and bulb
Body of clitoris
1-2cm wide and 2-4 cam long
- deep to the glans
- connected to the pubic symphysis by the string suspensory ligament
- compromised if the paired erectile corpora cavernosa surrounded by fibrous tunica albuginea.
- initially extends upwards, then reverses direction and branches into the two crura (wishbone configuration)
Crus of clitoris
- each crus is attached to the ischiopunic ramus: lateral and deep to the skin of the labia minora
- each crus is 5-9cm long and narrower than the body
- the most vascular part of the clitoris
Root of clitoris
- Deep to the skin of the vestibule
- connects the body to the crura
- overlaps the bulbs of the vestibule (clitoris)
Bulbs of the vestibule (clitoris)
- lie deep to the labia majora and against the distal vaginal wall
- fills the gap between the crus, body and urethra
- continuous with the glans and body
- triangular (3-7cm long)
- consists of erectile tissue (homologous to the corpus spongiosum)
- engorge during arousal (may perform some lubricative function as well
The clitoris plays an essential role in female…
Sexual pleasure
Components of the vulva
Mona pubis Labia majora Labia minora Clitoris Vaginal introitus Hymen
4 week olds do not have any differentiated…
External genitalia
Space between anus and genitals
Larger in males than females
Appearance of the ovary
+
innervated with
- paired
- small, oval, almond shaped, 2.5-5cm long
- white/yellowish colour
- lumpy surface
- located in the upper pelvic cavity against the back of the pelvic wall lateral to the uterus
- supplied by autonomic nerves and have a rich blood supply
Two main roles of ovaries
- Produce female gametes (oocytes)
- secrete hormones (estrogen, progesterone, androgens (testosterone) and Inhibin.
Ovaries are anchored by
Ligaments
- ovarian ligament: (thin, rope-like), attached ovary to uterus
- suspensory ligament (attached lateral surface of ovary to the pelvic wall, carries blood supply to ovary)
- the board ligament (thin sheet of connective tissue covering the ovaries, uterus, and fallopian tubes and anchoring them to the walls and floor of the pelvic cavity to keep in alignment. Is an extension of the peritoneum that covers the uterus as a double fold, attaching the lateral uterus to pelvic sidewalls. Contains a number of structures: the Fallopian tubes, the ovaries, round, suspensory and ovarian ligaments, uterine and ovarian blood vessels, never and lymphatic.
Sun compartments of the broad ligament
- mesomentrium
- mesosalpinx
- mesovarium
Mesometrium
The mesentery of the uterus= the largest portion of the broad ligament
Mesosalpinx
The mesentery of the Fallopian tube
Mesovarium
The mesentery of the ovaries
Mesentery
The mesentery is a fold of membrane that attaches the intestine to the abdominal wall to hold in place and bring blood vessels
The ovaries are covered by a thin ……., underneath which is the fibrous….
Surface epithelium
Tunica albuginea
Inside the ovary has the stigma, with an:
- outer cortex: dense tissue that contains developing oocytes
- inner medulla: contains blood vessels, lumps this vessels and nerves
Ovarian follicles
An enclosed tissue sac around each germ cell (oocyte)
Each oocyte I surround by a thin transparent membrane called…
The zona pellucida that is secreted by the oocyte
Within the ovary of a female of childbearing age- there are many ____ at different stages of development
Follicles
How are oocytes picked up by Fallopian tubes
When follicles rupture, the oocyte (with surrounding oophorous) is free within the body cavity to be picked up by the Fallopian tubes.
Fallopian tubes anatomy
Aka oviduct, salpinx, uterine tube
- paired tubes running from near the ovary to the top of the uterus
- muscular
- 10cm long (diameter of 1cm)
- made up of 3 layers of tissue
3 layers of tissue of Fallopian tubes
Oviductal serosa
Oviductal muscularis
Internal lining
3 primary regions of Fallopian tubes
Infundibulum
Ampulla
Isthmus
Outer layer of Fallopian tube tissue
Thin outer membrane, termed the ovuductal serosa
Middle layer of Fallopian tube tissue
Contains muscle, both inner circular and outer longitudinal muscle termed the oviductal muscularis
Contractions help transport the ovum/ embryo toward the uterus
Inner layer of Fallopian tube tissue
Has many folds, contains ciliated cells and non ciliated secretory cells that produce mucous and other secretions to help nourish eggs/sperm
Ciliary beating and mucous secretion also help with ovum/embryo transport
-these cells increase in activity near ovulation time
Infundibulum
- Funnel shaped and captures the egg
- opening=ostium
- has ciliated, finger like projections of erectile tissue (fimbriae)
- the cilia best towards the uterus (at ovulation, fimbriae engage and become turgid to assist with picking up of oocyte)
Ampulla
- Wide portion, adjacent to the infundibulum
- sure if fertilization
Isthmus
- narrow portion at proximal end
- where it opens into the uterus is called the uterotubule junction
- tubes held in place by the mesosalpinx portion of the broad ligament
Location of the uterus
- Anterior to the rectum and posterior/superior to the bladder
- normally slanted forward in body cavity anteverted, but can top backwards-retroverted
In a nulliparous female the uterus is the size and shape of a
Small pear
Uterus is comprised of what
Fondus and corpus (have 3 tissue layers) and cervical canal
The uterus is held in place by
4 uterine ligaments
A pair of Broad ligaments attach the
Uterus to pelvic wall on each side (mesometrium portion)
A pair of uterosacral ligaments attach the
Lower end of the uterus to sacrum (tail bone)
A pair of lateral cervical ligaments connect
Cervix and vagina to the pelvic wall
Round ligaments attach on
Uterus near entrance of oviducts and connect to the lower pelvic wall in the internal tissues of the labia majora. Ligament runs through the inguinal canal.
Females have a smaller ______ than males
Inguinal canal
What runs through the inguinal canal
The Round ligament of the uterus, nerves, blood and lymphatic vessels
Fundus
Dome shaped region above the points of entrance of the oviducts
Corpus (body) of uterus
- tapering central portion
- ends at the external constriction: the uterine isthmus (leads to uterine cervix)
Cervical canal
- small channel connecting the vagina and uterine cavities
- opening to uterine cavity (internal cervical os)
- opening to vaginal cavity (external cervical os)
- viewed through the vagina
- appears as a dome; bulges into the top of the vagina= ectocervix
Walls of the fundus and corpus layers
Perimetrium
Myometrium
Endometrium
Perimetrium
Thin outer membrane of connective tissues- continuous with covering in oviducts
Myometrium
- thick layer of smooth muscle and connective tissue: thickest in the corpus
- responsible for very strong contractions during labour: mass increase 24 fold during pregnancy
Endometrium inner layers can be divided into 2 layers
Stratum functionalis
Stratum basalis
Stratum functionalis
- thicker, inner layer
- cyclic changes to uterine glands and blood vessels due to female sex hormones
- contains coiled arteries which construct prior to menstruation and this ischemia causes degeneration and area to be shed during menses.
- during pregnancy develops the maternal part of the placenta
Stratum basalis
- thinner, outer layer
- contains blood vessels that add to menstrual flow
- generative layer, rapid mitosis, reforms a new stratum functionalis every month
- contains straight arteries for constant supple, which do not undergo cyclic changes
During pregnancy the myometrium (smooth muscle+ connective tissue)…..
Increase in mass by 24 fold and the muscle fibres increase in size about 50 micrometers to 500 micrometers
The uterus is most active when
During labour and delivery but also during menstruation (cramps) and may also contract during intercourse (orgasm)
Size of uterus during pregnancy increases from
0.2 lb to 2 lb (10 fold) at 9 months
Uterus+ contents at 9 months pregnant
7.5 pound baby 4 pound fluid 1.5 lb placenta 2 lb uterus 15 lb total (75x nulliparous)
The increase of size of uterus during pregnancy is related to
- enlargement of the muscle cells
- increase in number of muscle cells
- increase in amount of connective tissue (collagen)
Collagen is for
Strength and elastic divers for flexibility and stretch
What allows the uterus to love relative to the bladder and bowel during pregnancy
The ligaments
In addition to the ligaments, the uterus is also supported by the
Muscles of the pelvic floor-often weakened during pregnancy potentially leading to prolapse
Cervical cancel
The small channel without the cervix that connects the vaginal cavity with the uterine cavity (2-3cm)
Cervix is made up of what layers
Perimetrium
Myometrium
Endometrium
But the myometrium (muscle layer) is thinner and the endometrium is NOT shed
Cervical mucus
- glands lining the cervix decrease cervical mucus
- a mixture of water, glycoproteins, lipids, enzymes and inorganic salts
- reproductive female produces 20-60 ml/day
- changes in consistency tho right the month
- near ovulation: thinner and more alkaline to support sperm (supplements energy needs of sperm, protects from phagocytes and hostile environments of vagina/ uterus)
- other times: thicker to impede sperm penetration (cervical plug)
Anatomy of vagina
8-10cm long tube, normally collapsed
- passageway for menstrual flow, receptacle for the penis, birth canal
- made of 3 layers: tunica mucosa, tunica muscularis, tunica adventitia
- no glands in the vagina
Tunica mucosa
(With epithelial lining)=changes in thickness during menstrual cycle
- has folds (rugae) allowing stretch
- contains antigen-presenting cells
- contains lamina-propria sub-mucosa (dense connective tissue, elastic fibers and veins)
Tunica muscularis
Middle layer
-Smooth muscle embedded in connective tissue; sphincter at vaginal opening
Tunica adventitia
Outer layer= elastic connective tissue
-sensory nerve endings are located deep in the epithelium, mainly near the vaginal opening.
Vaginal epithelial cells
Within tunica mucosa, accumulate large amounts of glycoprotein, which certain bacteria metabolize to lactic acid; pH 3.5-4
Natural home of several microbes including various bacteria, fungi and Protozoa
Vagina
Some are important for maintaining the environment and others are potential pathogens and can be sexually transmitted.
What can kill off bacteria that function to produce the lactic acid (increases vaginal pH)
Antibiotics
Causes increased growth of yeast
Vaginal Douching
The washing/ flushing of the vagina with water or other fluids can disrupt the microbial balance and lead to a yeast infection or bacterial vaginosis
Anatomy of breasts
Paired, highly innervated, modified sweat glands overlying the pectoralis major muscles and ribs 2-6
Breasts and mammary glands are embryologically derived from
A “milk line” that runs from arm to leg buds
-usually in glans only one pair, through supernumerary nipples (0.2-2.5%) and glands (0.1-1%) is relatively common.
Functions of breast and mammary glands
Lactation -milk secretion
Sexual arousal
Sexual attraction
Mammary papilla
Centrally located Pigmented nipple, where lactiferous ducts empty through several openings
Areola
Area of pigmented skin surrounding the nipple (appears rough due to many sebaceous (oil) glands (prevents chapping/cracking during breast feeding)
What supports the breasts
Strands of connective tissue-suspensory ligaments of the breast (coopers ligaments) that run between the skin and fascia and extend inward into the breast as septa between the lobes of the breast-become looser with age or excessive strain.
Sensory nerves of breast
Located in the tip of the nipple and periphery of areola-respond to tactile stimulation- causes smooth muscles that run along the lactiferous ducts to contract and the nipples to become erect (excitation and nursing)- different from penile/ clitoral erection
In a non pregnant/ non nursing female the difference in size and shape of breasts is mainly related to
Fat content, not glandular tissue; size does not affect ability to produce/ secrete milk
Male mammary glands are capable of…
Growing and secreting milk if properly stimulated by certain hormones -gynecomastia
Why do females have permanently enlarged breasts
Don’t know
The breast is divided into
15-20 lobes by extensions of coopers ligaments
- surrounded by fat tissue
- subdivided into several lobules each with grape like clusters of 10-30 alveoli
Mammary alveoli
The functional unit of the mammary gland
-hollow sphere of milk-secreting cells
The ampulla or lactiferous sinus acts as a
Temporary storage area
Breast development in womb to birth
Begins with a thickening in the chest area-the mammary ridge or milk line. By birth, nipples and beginnings of milk-duct system are present.
Breast development at puberty
Buds appear, lobes, and ducts begin to develop, breasts enlarge with increase in grandular tissue;areola and nipple become radishes and form a second mound.
-tissue inactive in prepubertal females but begin to development as ovaries begin to secrete estrogen=alveoli and ducts begin to grow
During monthly cycle- breast changes
Estrogen in first half stimulates growth of milk ducts, then progesterone stimulates formation of milk glands
Breast changed during pregnancy
First half of pregnancy:
- growth of epithelial portions, reduction in the amount of fatty tissue
- secretory alveoli are stimulated by high estrogen; duct system by high progesterone.
Latter half of pregnancy:
-secretions begins; distension due to accumulation of secretion
Late in pregnancy and immediately after parturition:
-secrete colostrum (rich in lactoproteins , poor in lipids, contains laxatives to help remove meconium, antibodies to remove bilirubin that causes jaundice, vitamin k and b stimulate intestinal micro biome.
Breast changes several days postpartum
- milk secretions begin a few days after birth
- contains lipids, lactoproteins, sugars (milk is richest in first 4-5 minutes each session)
Difference of breast milk and cows milk
Breast:
- 30% casein, large amount is whey
- lysozyme levels are 3000x greater in humans
- 40-50% of calories from fat
- saturated and unsaturated fat varies with the mothers diet.
Cow:
- 80% casein, little whey
- no human antibodies
- 30% of calories from fat in 2% milk
- saturated and unsaturated fat varies with the mothers diet or additives
Control of lactation in late pregnancy
- high estrogen= alveoli growth and high progesterone= duct system
- suppresses prolactin (milk production)
- stimulates breast development
- production and secretion of colostrum
Control of lactation after birth
- estrogen and progesterone levels fall rapidly
- allows prolactin secretion to increase
- breast stops secreting colostrum
- secreted milk around 2-4 days post partum
Milk ejection reflex
What can hinder this
Infancy suckles nipple, nerve impulses reach the hypothalamus. Oxytocin is then released into the blood from the posterior pituitary and regales to the mammary glands. Oxytocin causes contraction of cells surrounding each alveolus and the milk is ejected. 30s reflex.
Stress can activate sympathetic nervous system which causes constriction of mammary gland blood vessels, reduced delivery of oxytocin and I hi Orion of milk ejection.
Conditioned stimuli
Can replace suckling as an initiator of milk ejection
- baby crying
- sounds
- smell of baby
Milk production pathway
- sucking increases PRH (prolactin real eating hormone) from the hypothalamus.
- triggers secretion of prolactin from anterior pituitary.
- prolactin stimulates alveoli to produce and secrete milk.
- baby suckling more= positive feedback leading to more prolactin= more milk
Suckling also increases…
Endorphins
-cause negative feedback to hypothalamus which reduces GnRH
Prolactin also reduces
Sensitivity of ovary to LH and FSH= lactation all contraception (usually less than 4-6 months
Good and bad choices for contraception when nursing
Good:
- barrier methods
- progesterone only contraceptives
Bad:
- IUD (oxytocin stimulates uterine contractions)
- combination contraceptive pill
- contains estrogen which interferes with prolactin
- effects of high estrogen in baby unknown
Oocyte
Female germ cell after beginning meiosis
Follicle
A bag/sack of tissue in the ovary that contains the oocyte
Corpus luteum
An endocrine gland formed from wall of an ovulated follicle
Corpus albicans
Connective tissue-filled structure. A remnant of the regressed corpus luteum
Zona pellucida
Acellular glycoprotein later surrounding the oocyte in the space between the oocyte and the membrana granulosa
Oogenesuis
- where
- when
- Occurs in the ovaries
- is cyclical
- begins at puberty to middle age (menopause) 12.5-51 years
- 38.5 years and 462 cycles
- no cycles during pregnancy and sometimes breastfeeding
Every oocyte is surrounded by a ____ and during each cycle:
Follicle
- an oocyte and follicle develop and an oocyte is released
- there are changes to the endometrium and other parts of the female reproductive tract and breasts
Cycles (menstrual/ uterine and ovarian) are____ and controlled by
Synchronized and controlled by hormones via both negative and positive feedback
Maturation of oocyte/ follicles
- begins at puberty
- occurs at intervals ~28 days
- is hormonal my controlled
- several follicles and primary oocytes are stimulated to mature each month by only one will reach full maturity and be ovulated.
Entries time from primordial follicle to Graafian follicle is
300 days
All remaining tertiary follicles/oocytes (about 20/ovary/month) are
Degenerated and become atretic
Oo genesis and follicular stages prior to birth
- oogonia (2n) divide by mitosis to product primary oocytes (2n)
- primary oocytes enter meiosis 1 prior to birth but are arrested in prophase 1 (still 2n) until puberty.
Oogenesis and follicular stages during/after puberty (occurs monthly)
- a number of follicles/oocytes begin development each month but only one oocyte will complete meiosis 1.
- LH surge prior to ovulation initiates resumption and is linked to loss in gap junctions between cells.
- others become artistic/degenerate
- results in a secondary oocyte (n) and the first polar body (n) which usually degenerates.
- secondary oocyte (n) enters meiosis 2, but arrested in metaphase 2
- secondary oocyte is ovulated (stuck in metaphase 2, unless fertilized)
What contours the follicles/ oocytes development each month
Maturation-promoting factor (MPF)
Oocyte loss
- the number of oocytes decreases throughout a women’s life
- peaks:midway during gestation ~7M
- at birth ~500k primary oocytes (within primordial follicles) in each ovary
- at puberty ~200k/ ovary
- by 35, <100 000
- virtually depleted by menopause
Only ____ released during monthly cycles, the rest are…..
400-500 oocytes
Degenerate=artresia (type of apoptosis= programmed cell death)
Cellular remnants of oocyte degenerates are removed by
Leukocytes
Artresia begins occurring before…. And con continues throughout a women’s…
Birth
Reproductive lifespan
Artresia is the fate of the the vast majority of….
Are new oocytes delveloped?
Oocytes and ovarian follicles
No
How can gradual loss in follicle number from gestation to menopause be altered?
Can occur earlier if
- smoking
- part of a multi birth
- poor childhood weight gain
- nulliparous
- earlier age of menarche (period)
Unconsistent effects: BMi, socio-economic stays, aspects of diet (vegan/ meat)
Follicular development can be divided into 4 main stages
Primordial follicle
Primary follicle
Secondary follicle
Tertiary (Graafian) follicle
Stages of follicular growth
Prior to birth
- each oocyte is surrounded by a primordial follicle
- one layer of flattened squamous granulosa cells (membrana granulosa) bounded by a basement membrane
- total size ~50 micrometers
Stages of follicular growth
At puberty
- every day, a few primordial follicles initiate growth to be a primary follicle
- one layer of granulosa cells, but they are now cubodial and the oocyte is slightly larger
- zona pellucida develops
- total size: ~100 micrometers
Primary follicle develop into the secondary follicle over…. How long and what occurs
4 months (100 micrometers)
- mitosis of granulosa cells to produce multiple layers surrounding the oocytes, thus membrana granulosa now 2-6 cell layers thick.
- theca (muscular) layer begins forming on the periphery.
- blood vessels invade the thecal layer, but the granulosa layer is a vascular.
- follicle cells become active in secreting hormones (estrogen, testosterone)
- a few secondary follicles become tertiary follicles, many become atretic
Secondary follicles develop to tertiary follicles over how long and what occurs
~2-3 months
- granulosa cells secrete fluid which accumulates between cells
- antrum forms, containing Antral fluid (follicular fluid) which contains steroid and protein hormones, anticoagulants, enzymes and electrolytes.
- the membrana granulosa is now several layers thick
- theca differentiates into a theca interna and theca externa
Theca interna and theca externa
Containing glandular cells and many small blood vessels
Consists of dense connective tissue with larger blood vessels
Secondary follicles to tertiary follicles then begin the bulge and release which is..?
- a mass of granulosa joins the oocyte with the follicle (cumulus oophorus)
- will remain attached to the oocyte as it enters the oviduct. The spermatids need to penetrate their layer to get to egg.
- granulosa cells develop connections to oocyte and to each other, via gap junctions and allows for chemical signalling.
Stages of tertiary follicle growth
Early
Late
Graafian
Early tertiary follicle growth
Begin to accumulate antral fluid, but not yet one cavity. Grow from <1-5mm
Late tertiary follicle growth
Have single antrum, now 10-14mm
Graafian tertiary follicle growth
- largest (15-25mm) and most mature
- theca extremely vascular
- only “the chosen one” menstruated and all others become atretic and die
- growth to this stage is FSH dependent and may be stimulated by LH too.
Follicular growth and ovulation
- if no fertilization, the secondary oocyte degenerates
- if fertilization: completion of meiosis 2 (unequal division producing an ovum (n) and second polar body degenerate). When fertilization is zomplete= zygote.
The chosen one
Only one follicle usually develops to graafian stage and releases a secondary oocyte each month.
It is thought that the largest/ most dominant follicle…..
- accesses the most FSH
- is more vascular
- has more granulosa cells with FSH receptors
- estrogen from dominant follicle exerts negative feedback to reduce FSH secretion, which may diminish other follicles
Immediately before ovulation, the ____ appears
Stigma
- a small, pale, a vascular region where the surface epithelium and thecal layers become thinner and dissociated.
- membrana granulosa degenerates in this area
Reduction in the sidle strength of follicular wall is due to
- estrogen-induced production of collagenase from connective tissue breakdown
- induced inflammation and release of prostaglandins
- prostaglandins constrict blood vessels and reduce blood supply to degenerating tissue.
- pressure in the antral cavity causes stigma to cone and tear
- the detached oocyte with its cumulus oophorus oozes our with the escaping fluid.
After ovulation the ____ develops
Corpus luteum
How does the corpus luteum develop
- granulosa cells in collapsed follicle divide and fill antral cavity
- blood vessels from thecal layer grow/penetrate the central literal cell mass
Cells of corpus luteum secrete high levels of…
Progesterone and moderate estradiol
Delta 4 pathway and requires LH
When does the corpus luteum develop
During the second half of menstrual cycle
- if not pregnant, degenerates and fills with connective tissue= corpus albicans
- in case of pregnancy, corpus luteum persists for 1st trimester
Where are primary oocytes (2n) arrested in propose 1 of meiosis
In primordial, primary, secondary and early tertiary follicles
During follicular development- cytoplasmic bridges/gap junctions exist….
between adjacent granulosa cells and between the granulos cells and the oocyte
Cholesterol is the precursor to all sterilize hormones secreted by the ovary such as:
- estrogens (estradiol, esterone)
- progestins (progesterone)
- androgens (testosterone)
Pathway of cholesterols to the needed hormone
- first step: steroid acute regulatory protein (stAR) to move cholesterol to the inner mitochondrial membrane (enzyme locations) and smooth ER.
- then, conversation of cholesterol to intermediate, pregnenolone
- after that are two pathways: delta 4 and delta 5.
Delta 4 and delta 5 pathways
Delta 4: corpus luteum- progesterone and estradiol
Delta 5: large tertiary follicles- estradiol and esterone
In both pathways, androgens are precursors to estrogens
Within the developing follicle, neither cell type (granulosa or thecal) contains all the needed enzymes to create needed hormones…. Sooooo
They coordinate to complete steroid genesis
Ex: in tertiary follicles the theca interna makes androstenedione which diffuses to granulosa cells, which can convert it ti testosterone and estradiol, which is transported back to the theca= the two cell model of ovarian steroid genesis.
Non steroidal hormones produced by the ovary include
Inhibin, activin and follistatin
Tertiary follicle follows which pathway to produce mostly what
Delta 5
Estradiol
Preovulatory follicle (Graafian follicle after LH surge but before ovulation) and the corpus luteum follows which path and produces
Delta 4
Progesterone and some estradiol
Follicular growth and steroidogenesis are controlled by …
FSH AND LH
FSH in follicular growth and steroidogenesis
- growth to the antral stage is gonadotropin independent, through low levels of FSH promote growth of primary and secondary follicles
- rapid growth of granulosa cells in tertiary follicles, formation of antrum, and estrogen production is dependent on FSH
- regulates production of steroids by granulosa cells
LH on follicular growth and steroidogenesis
- stimulates production of androstenedione in thecal cells in late secondary and tertiary follicles
- just prior to ovulation, LH receptors also appear on granulosa cells-shift = luteinization of granulosa cells leads to final growth, maturation and ovulation.
- regulates production of steroids by theca cells and luteal cells.
As tertiary follicles grow they increase ____ production to make the majority produced by the body
Estrogen
Most female mammals are sexually receptive during…
Other methods
Ovulation (estrous)
- monoestrous: one cycle per season
- increased ovulation (rabbits, cats)
- spontaneous ovulation (humans, rodents)
Social interactions can influence estrous cycles
Whitten effect (only when male is present), called the dormitory effect. In humans some studies inconclusively show this. Pheromones may play a role
Who has menstrual cycles
Only a few primates-baboons, apes, monkeys and also bats (menses)
Menstrual cycle overview
- typical human 28 day cycle coordinated by neuroendocrine events (hormones), ovaries and uterus.
- day 1= fist day of menstruation.
- cycle controlled by GnRH pulse generator
- has 3 phases
3 phases of menstrual cycle
Menstrual (menses)
-day 1-5
follicular (estrogenic or proliferation )
-day 5-14 (most variable in duration)
Luteal (secretory or progestational)
-day 14-28
Growth of follicles coincides with
Following ovulation, the luteal phase coincides with the
Menstruation and the proliferation phase of the uterus
Secretory phase of the uterus
The frequency of GnRH pulses_______ closer to ovulation which cause..
Increases
Drive LH and FSH to spike
Hormonal changes during menstrual phase
- GnRH in females has Monty and diurnal cycles/pulses
- during this phase GnRH is secreted at a low level from hypothalamus, which would lead to stimulation of LH and FSH from the anterior pituitary (at low levels)
- LH and FSH stimulate beginning of tertiary follicle growth and oocyte maturation, with slight increase starting around day 3 (not ovulation initiate)
- ovarian hormones (progesterone and estrogen) are very low!!!
Ovarian/follicle changes during menstrual phase
- follicle enlarges to early tertiary stage
- initial development of the follicle to antral stage is gonadotropin independent so can proceed without FSH and LH
- oocyte grows: receives materials from blood vessels in the theca externa
- dominant follicles secrete suppressors (estrogen and Inhibin) to prevent development of additional follicles via negative feedback
- modest rise in LH and FSH at day 3 the follicle starts to slowly increase steroidogenesis to secrete estradiol and androgens
Uterus changes in menstrual phase
- sloughing of the endometrium (stratum functionalis)
- low ovarian hormones (progesterone) act to signal this event
- stratum functionalis is she’s ad menstrual flow (3-7 days)
- by day 4- epithelial cells of stratum funtionalis are being repaired by stratum basalis, blood vessels regenerate (spiral arteries)
- end of menstrual phase, the endometrium is 0.5-3mm and consists mostly of stratum basalis
Menstrual flow
Average volume: 30-80ml to 250ml (1 cup)
- volume lost may increase with IUD/ decrease with Pill
- volume lost tends to decrease with age though may become heavy in perimenopause
Contents of menstruated flow
- arterial and venous blood (plasmin dissolved clots to keep blood liquid)
- epithelial cells from stratum functionalis
- mucus and other secretory materials from uterine and cervical glands
Hormone changes in early/mid follicular phase
- secretion of LH begins to increase rapidly due to increased estrogen with low progesterone and increase frequency of GnRH
- FSH remind low or falls slightly due to differential effect of GnRH pulse frequency/ sensitivity on FSH and production of inhibit in the granulosa cells of the ovary
Hormone changes in mid to late follicular phase
- rapid increase in LH continues (increased estrogen)
- stimulates complete development of Graafian follicle and start of ovulation
- initiates production of progesterone
- stimulates the resumption of meiosis 1 in primary oocyte
- rapid rise in FSH a side effect of increase in GnRH
Hormonal changes in late stages of follicular phase
- FSH, LH, and estrogen levels start to decline
- progesterone levels slowly start to increase
Ovarian/ follicle changes during follicular phase
- ovulation occurs 12-36 hours after LH spike ~day14. Usually one follicle fully matures, those that are most sensitive to LH.
- it will ovulate that cycle (usually only one-ovaries tend to alternate)
- during ovulation, first the stigma appears
- Graafian follicle responds to LH surge, and tensile strength if wall decreases and bursts.
- secondary oocyte released from Graafian follicle
- The follicle granulosa cells that remain collapse, antral/follicular fluid released, small clot forms in collapsed follicle (corpus hemirrhagicum)
Uterus changes during follicular phase
- cause of proliferation phase of uterus
- rising estrogen levels
- secreted by the dominant ovarian follicle in response to FSH
-anatomical changes include: the stratum functionalis rebuilds/ thickens (produced from stratum basalis), tubular glands enlarge, spiral arteries proliferate and elongate.
Ovarian cycle phases
Uterine cycle phases
Combined menstrual cycle phases
Early follicular, late follicular, luteal
Menstrual phase
Proliferation phase
Secretory phase
Menstruated phase
Follicular phase
Luteal phase
Effects of estradiol on follicular phase of menstrual cycle during EFP, MFP and LFP
EFP-early follicular phase (low E, High FSH/ LH, no negative feedback)
MFP-Midfollicular phase (moderate E, Negative feedback on FSH/LH)
LFP- Late follicular phase (very high E, positive feedback and LH surge)
The luteal phase is generally similar in length, even with different….
Total cycle length
The menstrual cycle- early/ mid luteal phase hormonal changes
- corpus luteum secreted progesterone, estradiol and inhibin
- progesterone and estrogen surge at day 21, with progesterone to estrogen ratio high
- inhibin slows down GnRH pulses and exhibit negative feedback on FSH and LH
- An increase in inhibin A from the granulosa cells of ovary also inhibits FSH, when estrogen is high
- LH and FSH levels down from spike (low levels inhibit new follicles and ovulation)
The menstrual cycle- late luteal phase
- if no pregnancy, corpus luteum degenerates (due to LH)
- the progesterone and estrogen levels decline, with progesterone to estradiol ratio low
- no longer inhibition on GnRH, so pulses speed up
- no longer negative feedback on FSH and LH, so levels start to rise.
The menstrual cycle- ovarian/ follicle changes during luteal stage
The collapsed follicle is transformed into the corpus luteum:
- granulosa cells grow rapidly and accumulate lipid (carotene= ywllowish colour) lutein cells
- corpus luteum is a temporary endocrine gland
- development of corpus luteum required LH
Luteal phase if no pregnancy and if pregnancy
If no pregnancy:
- late in the phase the corpus luteum degenerates
- turns into the corpus albicans, which overt time will fold inward on itself and effectively disappear.
If pregnancy:
- corpus luteum becomes the corpus luteum of pregnancy
- continues secreting progesterone and estrogen until the placenta takes over
Early/ mid Luteal phase uterus changes
- changes in response to increase in progesterone
- the stratum functionalis thickens further
- edema of the tissues (swells with fluid) becomes thick and spongy
- secretion of uterine glands (secretions contain glycogen
- coiled arteries elongate, become more convoluted
Uterus changes in late luteal phase
- progesterone falls toward day 23-25 and lead to:
- premenstrual changes in the spiral arteries (construction followed by necrosis and dilation)
- endometrium shrinks to 3-4mm
- necrosis prepared endometrium for menstruation
Beyond ovaries and uterus: Fallopian tube
Follicular phase changes
Early/ mid stage
-in response to the increase in estrogen, the number of cilia in infundibulum increases as well as the rate of mucus secretion.
Late stage
- secretion rate is maximized
- blood engorgement of the fimbriae is also greatest at this time.
Beyond ovaries and uterus: Fallopian tube
Changes in luteal phase
Early stage
-ciliary beat frequency increases
Late stage
-progesterone levels increase leading to a decrease in the number of cilia and CBF as well as secretory activity
Is the cervical mucus membrane shed?
No
The cervix in early/ mid follicular phase
- low estrogen
- cervical muscles contracted
- mucus=viscous and hostile to sperm
The cervix in mid-late and late follicular phase
High estrogen
- ovulation is nearing with an increase in estrogen and low progesterone
- cervical muscles relax: opening the external cervical os slightly
- cervical mucus is thin and clear, slippery and stringy
- total volume of vaginal discharge increases as much as 10x, also changes in electrolytes and pH=more sperm friendly.
Cervix changes in the luteal phase
Due to increase in progesterone
- cervical muscles contracted
- less mucus, viscous and hostile to sperm
- if pregnancy occurs: the mucus will form a plug
Does the vagina change much during menstrual cycle
Not very much, but secretions from cervix and flow from the uterus could alter pH.
Micro biome
The collective bacteria that are on and in our bodies
Changes in vaginal micro biome during menstrual cycle
- vaginal microbial diversity increases during menses
- lactobacillus is a prominent bacteria in vaginal micro biome that decreases during menses
How does the hypothalamus respond to estrogen and other sex hormones?
GnRH neurons do not directly respond to sex steroids. Instead, the steroids act on kisspeptin secretion neurons, which release kidspeptin to signal to the hypothalamus.
Estrogen has positive feedback on which neuron
Kisspeptin neurons in the anteroventral periventricular nuclei to increase kisspeoptin release
Estrogen has negative feedback on which neurons
Kiss neurons in the actuate nucleus and reduces pulse frequency
