Mar 6th Flashcards
broad ligament anatomy
- mesovarium (ovaries)
- mesosalpinx (oviducts)
- mesometrium (uterus, cervix)
broad ligament function
- Supports (“hangs”) several anatomical
components of the reproductive tract - Prevents friction
- Houses vascular supply, lymphatics and nerves
What are the ovaries?
Glandular organs that house female gametes within ovarian follicles.
What are the three anatomical layers of the ovary?
- Tunica albuginea – outer connective tissue
- Cortex – houses follicles & corpus luteum
- Medulla – contains blood vessels, lymphatics, & nerves
What are the three main functions of the ovary?
- Oocyte production (oogenesis)
- Ovarian follicle development (folliculogenesis)
- Hormone production (estradiol & progesterone)
what are the oviducts
Dual channels between the ovaries and uterus that transport oocytes, embryos
and spermatozoa
what is the anatomy and function of the oviducts
- Infundibulum
- Capture cumulus-oocyte complex - Ampulla
- Site of fertilization - Isthmus
- Transport and short-term* storage of sperm
what is the uterus
hollow, pear-shaped muscular organ situated in the pelvic cavity
anatomy of the uterus
- Endometrium
- Myometrium
- Perimetrium
function of the uterus
- Site of embryo implantation & growth
- Sperm transportation
- Responsive to hormones —–> contractions
- Prostaglandin secretion -> luteolysis
what is the cervix
muscular tunnel-like organ located at the lower, narrow end of the uterus
anatomy of the cervix
- Endocervix (monolayer columnar epithelium)
- Ectocervix (stratified squamous epithelium)
- Os
- Cervical folds + crypts*
function of the cervix
- Barrier for uterine protection
- Mucus production
- Non-pregnant: lubrication
—–> facilitate sperm motility - Pregnant: mucous plug –> seal pregnancy
what is the vagina
Elastic, muscular canal of 7 to 10 cm in length that serves as an entrance to
the female reproductive tract.
anatomy of the vagina
- cranial region
- caudal region
function of the vagina
- Copulatory organ
- Birth canal
- Mucus production for lubrication
- Low pH (3.8 – 4.5)–> microenvironment regulation
what is the primary function of the vulva
provides anatomical closure to vagina
how does the vulva help protect the reproductive tract
minimizes entry of foreign materials
what is the clitoris
A highly innervated erectile tissue, homologous to the penis.
what is a mature gamete and gonad in female reproduction
- oocyte (egg)
- ovaries
what are the Two Cycles Occurring Simultaneously
- ovarian cycle
- menstrual cycle
What is the menstrual cycle?
A series of changes in hormone production & uterine structure that make pregnancy possible (uterine cycle).
What is the ovarian cycle?
A series of changes in the ovary, including follicle maturation, ovulation, & corpus luteum formation (folliculogenesis).
What are the two main cycles involved in female reproduction?
The uterine (menstrual) cycle & the ovarian cycle.
What is folliculogenesis?
The follicular phase of the ovarian cycle, where ovarian follicles develop and support the oocyte.
What is the function of ovarian follicles?
They protect the oocyte, provide nutrition, biochemical support, and secrete hormones.
What is the first stage of folliculogenesis?
Primordial Follicle – A single layer of flat cells surrounding the oocyte, representing the ovarian reserve.
What is the second stage of folliculogenesis?
Primary Follicle – A single layer of cuboidal cells surrounding the oocyte; produces estradiol (E2).
What is the third stage of folliculogenesis?
Secondary Follicle – 2-3 layers of cuboidal cells surrounding the oocyte; continues to produce E2.
What happens in the antral follicle stage?
An antrum (fluid-filled cavity) forms, containing E2; development is dependent on LH and FSH.
What happens to the follicle immediately after ovulation?
It becomes the Corpus Hemorrhagicum, containing blood from ruptured vessels.
What is the function of the corpus luteum?
Secretes progesterone (P4) to maintain pregnancy.
What happens if pregnancy does not occur?
The Corpus Luteum regresses into the Corpus Albicans, a small white structure, which eventually disintegrates.
what is the structure and function of the antral follicles?
Structure
1. Theca externa
2. Theca interna
3. Granulosa cells
4. Cumulus-oocyte complex
Function
- Produce estradiol (E2) à regulates ovarian
and uterine cycles
- House and protect the maturing oocyte
theca externa
- loose connective tissues
- surrounds and supports the follicle
theca interna
- just beneath the theca externa
- LH receptors
- produce androgens (testosterone)
Granulosa cells
- mural granulosa cells line the inner part of the basal lamina
- FSH receptors
- convert androgens into estradiol (E2)
What is the Corpus Luteum (CL)?
An endocrine gland formed from the remaining follicular cells after ovulation.
What hormone does the CL primarily produce?
Progesterone (P4).
What percentage of the CL is made up of blood vessels?
~50% of its volume.
What percentage of the CL is made up of luteal cells?
~30% of its volume.
What makes up the remaining ~20% of the CL?
Pericytes, fibrocytes, nerves, immune cells, and smooth muscle cells.
What are the two transport proteins for progesterone synthesis?
Low-density lipoproteins (LDL) and High-density lipoproteins (HDL).
What type of receptors do luteal cells express?
LH receptors.
What enzyme does LH activate in luteal cells?
Adenylyl cyclase.
What is the function of adenylyl cyclase in progesterone synthesis?
It converts ATP to cAMP.
What does cAMP activate in the luteal cell?
Protein kinases.
What are the three key functions of protein kinases in progesterone
a) Enhance internalization
b) Activate cholesterase
c) Activate StAR protein
What is cholesterol converted into during progesterone synthesis?
Pregnenolone.
What is pregnenolone converted into?
Progesterone (P4).
what does the HPG axis consist of
- hypothalamus
- pituitary glands
- gonads
Endocrine Regulation
- Hypothalamus secretes GnRH à pituitary gland
- Pituitary gland releases LH & FSH (gonadotropins)
–> into systemic circulation - LH & FSH reach the ovaries –> Ovarian follicle & CL cells have LH & FSH receptors
- Ovaries secrete E2 (follicular phase) or P4 (luteal phase)
- Feedback mechanisms mediate endocrine response
What hormone stimulates follicular development in the ovarian cycle?
Follicle-Stimulating Hormone (FSH).
What hormone is responsible for triggering ovulation?
Luteinizing Hormone (LH).
What does LH stimulate in theca interna cells?
Testosterone production.
Where does testosterone produced by the theca interna cells go?
It diffuses into granulosa cells (GCs).
How does LH affect granulosa cells?
LH stimulates production of LH receptors on outer GCs.
What is the result of LH receptor production in granulosa cells?
It triggers resumption of oocyte meiosis.
What happens after the LH surge?
- Weakens follicle walls
- Collapses follicle
- Causes ovulation
Endocrine Control of Estradiol Production
- GnRH from hypothalamus —-> pituitary gland
- LH & FSH released from pituitary gland
- Theca cells
- LH binds to theca cells
- Produce testosterone - Granulosa cells
- FSH binds GCs → ↑ recruitment of aromatase
- Convert testosterone to estradiol
What structure does LH induce after ovulation?
Formation of the corpus luteum.
What is the main estrogen secreted by ovarian follicles?
Estradiol (E2).
What does E2 stimulate to increase follicular sensitivity to FSH?
Production of FSH receptors.
What effect does increased E2 in the antral follicle have on the pituitary gland?
Induces positive feedback.
How does E2 regulate ovulation?
By providing positive feedback to the pituitary gland, leading to the LH surge.
What hormonal change induces the LH surge before ovulation?
Increased estradiol (E2) during the dominant follicle stage.
How long before ovulation does the LH surge occur?
2 days before ovulation.
What structural changes occur in the follicle due to the LH surge?
Weakening of follicle walls and increased antral pressure.
What happens when the follicle ruptures?
The cumulus-oocyte complex is released.
Follicular Phase Steps
- Hypothalamus releases GnRH, stimulating the anterior pituitary to secrete FSH and LH
- FSH stimulates the recruitment and proliferation of new
follicles.
* ↑ FSH receptors on GCs → ↑ sensitivity
* ↑ aromatase activity - LH stimulates the follicles
* Theca cells generate testosterone
* Diffuses to GCs → converted by aromatase to E2 - ↑ E2 in dominant follicle → + feedback to hypothalamus
- Peak E2 à GnRH surge à LH surge
- LH surge
* Resumption of meiosis in oocyte
* Follicle weakening and collapse = ovulation
hat process does the LH surge trigger in the remaining granulosa and theca cells?
Luteinization – conversion into luteal cells.
What hormones do luteal cells produce?
Progesterone (P4) and estradiol (E2).
How does P4 contribute to the luteal phase?
Stimulates endometrial gland secretions.
What role does E2 play in the luteal phase?
Stimulates spiral artery development.
What triggers menstruation?
A decrease in progesterone (P4) and estradiol (E2) due to lack of implantation.
What is expelled from the uterus during menstruation?
~80 mL of blood, fluid, and cell debris from the upper endometrial layer.
What is the difference between overt and covert menses?
- Overt menses: Menstrual bleeding due to endometrial spiral arteries (primates).
- Covert menses: No bleeding; endometrium is shed without spiral arteries (other mammals, estrus cycle).
1st phase in the uterine cycle
Proliferative phase
- Occurs during follicular phase
- Increased E2 stimulates growth of endometrium
2nd phase in the uterine cycle
Secretory phase
* Occurs during luteal phase
* Increased P4 from CL stimulates development of uterine glands
* Endometrium grows in thickness due to E2 & P4
3rd phase in the uterine cycle
Menstrual phase
* Necrosis & sloughing of endometrium
* Result of decrease in ovarian hormone secretion (E2 & P4) during late luteal phase
functional cysts
- follicular cysts
- luteal cysts
non-functional cysts
- dermatoid cysts
- cystadenoma
- endometrioma
PCOS
- Sparse, frequent, irregular menses
- Increased androgen production
- Multiple follicular cysts in cortex
What hormones do birth control pills contain?
Synthetic estrogen and progesterone.
How do birth control pills prevent ovulation?
- Override the system with high hormone levels.
- Inhibit pituitary secretions through negative feedback.
- Block the LH surge, preventing ovulation.
What happens to estrogen levels during menopause?
Ovaries stop secreting estrogen due to follicle depletion.
What is estriol, and where is it made?
Estriol is a weak form of estrogen made in adipose tissue.
Folliculogenesis
a continuous process
occurring cyclically for primordial follicle
recruitment to large antral follicle formation and ovulation
Oogenesis
a discontinuous process for
the development of an ovum into a cell
competent to further develop into an
embryo when fertilized
What is the main function of the oocyte cytoplasm?
Provides nourishment (vitellus/yolk) to the embryo.
Why does the oocyte undergo asymmetric cell division?
To conserve cytoplasm and sustain early embryonic development.
What is the function of the corona radiata?
Granulosa cells surrounding the oocyte that coordinate oocyte development via gap junctions.
What is the zona pellucida, and what does it do?
A protective membrane that facilitates sperm binding.
What do cortical granules do?
Prevent polyspermy by releasing enzymes.
1st step of oogenesis
Oocytogenesis
* Mitotic divisions resulting in more oogonia
* Occurs during embryonic development
2nd step of oogenesis
Ootidogenesis
* First meiotic division
* Results in secondary oocyte and
polar body
* Occurs after puberty, cyclically
3rd step of oogenesis
Oogenesis
* Completes second meiotic division
* Results in a mature ovum and two polar bodies
* Occurs after fertilization in mammals
When does oocytogenesis occur?
During embryo development.
When does mitosis of oogonia stop?
At the formation of primordial follicles.
What do oogonia differentiate into?
Primary oocytes.
What happens to primary oocytes during embryonic development?
They develop a germinal vesicle (GV) and enter meiosis I.
At which stage is meiosis I arrested in primary oocytes?
Diplotene stage of Prophase I.
Why does nuclear arrest occur in primary oocytes?
To protect DNA from damage.
When are all primary oocytes arrested in Prophase I?
At birth.
What triggers the resumption of meiosis I in oocytes?
The onset of puberty.
What is the function of the zona pellucida (ZP)?
Covers and protects the oocyte, with ZP proteins aiding fertilization.
Why are gap junctions important in oocytes?
They allow cytoplasmic communication between the oocyte and granulosa cells.
What key changes occur in oocytes at puberty?
Growth in cytoplasmic volume and cytoplasmic maturation.
What marks the completion of meiosis I in oocytes?
The formation of a secondary oocyte and a polar body.
What event triggers the resumption of meiosis I?
The LH surge.
How does high LH concentration affect mural granulosa cells (GCs)?
It stimulates LH receptors on mural GCs.
What happens when gap junctions deteriorate?
- Reduction of oocyte cAMP
- Deactivation of kinases
- Activation of MPF (Maturation Promoting Factor)
What structure is extruded after meiosis I?
the first polar body
What characterizes oogenesis?
Continuation of meiosis II and nuclear arrest of secondary oocytes.
At what stage is ovulation arrested?
Metaphase II.
when does the resumption of meiosis II and its completion occur
after fertilization
What is an oocyte?
An immature female gamete that has not yet completed meiosis.
What is an egg (ovum)?
A mature female gamete that has completed meiosis and is ready for fertilization.
