Module 4: Reproductive System Flashcards
What are gonads?
- Ovaries
- Testies
Are ovaries connected to the fallopian tubes?
No, they’re attach to a ligament
Are fallopian tubes unidirectional?
No, they’re bidriectional
What is the structure of the ovaries?
- strong matrix (connective tissue, nerves, lymphatic and blood vessels
- Follicles
- Tunica albuginea
- Surface epithelium
What is the name of the follicle that has been developed during birth
Primordial follice
What are the 7 phases of follicles?
- Primordial follicle
- Primary follicle
- Secondary follicle
- Early Antral follicle
- Antral follicle
- Preovulatory follicle
- Ovulatory follicle
What size follicle is estrogen produced by?
Larger follicles
When does menopause start?
When there’s about <1000 primordial follicles
What are the different cell types during folliculargenesis?
- Oocyte
- Granulosa cells
- Basement membrane
- Inner and outer theca cells
- Stromal cells
What is the cluster of cells surrounding the oocyte after ovulation?
Cumulus cells
How does primordial and preantral cells grow?
From factors release by the ovary. They are gonadotropin independent (no gonadal receptors)
What does exogenous mean?
To have external factors affecting your development
When are gonadotropin receptors developed?
In the early antral and preovulatory phases
Where are the gonadotropin receptors developed?
On the granulosa cells
What factor does follicles create themselves?
Inhibin
Why do follicles create inhibin?
To create a negative feedback loop to the pituitary gland so only 1 egg becomes dominant
Which follicles create high oestogen?
Early and antral follicles
Which follicles creates high amount of oestogen for 24 hours?
Preovulatory
What are the 4 phases of arrest in meiosis?
Prophase
Metaphase
Anaphase
Telaphase
When does mitosis happen in oogenesis?
Prenatal only
When does the primary oocyte arrest?
Prophase 1
Which follicles grow during prophase 1?
Primordial into secondary
When is meiosis 1 complete?
From childhood to adolescent, becomes an antral follicle.. will arrest at metaphase 2
When does meiosis 2 complete?
After fertilisation
What happens to polar bodies?
They degenerate
What is the life cycle of an oocyte?
Primordial germ cell migrates to gonads
Becomes oogonia and begins meiosis
Becomes oocyte
Primordial follicle
Primary follicle
Secondary follicle
Early antral follicle
Antral follicle
Preovulatory follicle
Fetus
Baby
What is the hypothalamic-pituitary-gonadal-axis?
The loop relationship between gonadoreleasing hormones and see hormones
Describe the hypothalamic-pituitary-gonadal-axis
- Hypothalamus stimulates anterior pituitary gland to release GnRH
- Anterior pituitary releases LH and FSH
- FSH and LH moves to the gonadotropin to stimulate follicle growth
- Follicles sends negative feedback loop back to AP and Hypo through inhibin to stop the release of FSH and LH
This is done in a pulsatile fashion
Why is hypothalamic-pituitary-gonadal-axis done in a pulsatile fashion?
The gonadotrope cells become desensitised to GnRH. Which will reduce LH and FSH release, which will reduce steroid production
What will a fast pulse of GnRH achieve?
Increased LH
What will a slow pulse of GnRH achieve?
Increase FSH
What is the 2 cell gonadotropin hypothesis?
- Cholesterol is released by the blood to the theca cells where the g couple protein receptor LHR accepts LH. This produces androgen (steroids- testosterone)
- Androgens move across basement membrane of granulosa cells and triggers the FSHR to accept FSH.
- Activation causes the enzyme aromatase to release and convert androgens to oestrogens
- The peptide hormone inhibin creates a negative feedback loop to reduce release of LH and FSH from the pituitary gland
- This causes smaller eggs to deteriorate and enables and single egg to fertilize
How is ovulation initated?
Through a surge of LH via a positive feedback loop due to oestogen.
What is the purpose of the corpus luteum?
To crate progesterone, which maintains the pregnancy
What happens to the corpus luteum if no pregnancy?
It deteriorates and menstruation occurs
What is another name for the menstrual cycle?
Uterine cycle
Define the uterine cycle
A cyclic change in endometrium in response to fluctuating ovarian hormone levels
Des rive the timeline and phases of the uterine cycle
- Days 1-5 menstrual phase
- Days 6-14 proliferative phase (preovulatory)
- Days 15-28 secretary phase (post ovulatory)
What are the 2 layers of the endometrium?
Basal and functional
Which layer sloughs from the endometrium?
Functional layer
How does endometrium thicken?
- A spike in endometrium just before ovulation also causes a spike in LH
- This creates the corpus luteum, and a progesterone spike
- These spikes cause a thickening of the endometrium
Describe the actions of estrogen in reproductive organs
- Within the ovary thr developing follicle and corpus luteum is the major source of oestrogen
- It is stimulated by the release of LH and FSH which creates both positive and negative feedback loops to control gonadotropin within the pituitary gland.
- These factors stimulate growth and maturation of the reproductive organs , promote the proliferative phase of the uterine cycle, stimulate watery mucus production ans activity of fimbrar and uterine tube cilia
- During pregnancy the mammary glands and genetlilia swell
Describe the actions of progesterone on reproductive organs
- The corpus luteum is the major source of progesterone and is stimulated by the release of LH to create a negative feedback loop of gonadotropin vie the anterior pituitary gland
- It co-operates with oestrogen to enlarge breasts, promote secretary phase of uterine cycle and creates viscous mucus production
- It enhances the beating of cilia in uterine tube, promotion sperm and egg meeting.
- During pregnancy it quietens myometrium and helps mammary glands produce milk
At what age does the suspension ligament elongate?
10-15 weeks, in utero
Why do testes hangoutsidr of the body?
Thermoregulation
What is the life cycle of sperm?
- Gonacyte (newborns)
- Spermatogonia
- Primary spermatoyte
- Secondary spermatocyte
- Spermatid
- Spermatozoon
What is the pampiniform venous plexus?
The veins and arteries within the scrotum to draw heat away from the testes
What is a cremastor muscle?
The muscle that moves the testes up and down for thermal regulation
What is the dartos muscle?
Afascia muscle that causes the scrotum to wrinkle, increasing surface area, allowing for cooling to occur faster
Where is sperm produced?
In seminiferous tubules
What is the rete testis?
A passage for sperm to move into the epididimus
What is the purpose of the epididmus in the male reproductive system?
To give sperm the ability to swim, it takes about 20 days. Before moving into the vas defrens
What is the purpose of the vas defrens in the male reproductive system?
Soerm ejaculation
What area of the male reproductive system is sperm stored?
The epididmus, for several months
Describe the features of the intratubular compartment of the testis
- Lines with complex stratified germinal cells
- Contains sperm and sertoli cells
Describe the features of the peritubular in the testes
- Contains androgens made by leydig cells
- Has neuronal and vascular elements
What cells great sperm?
Sertoli cells
Where do sperm first start in the sertoli cell?
On the basal layer and move into the lumen
Describe the process of spermogenesis
- Stem cell spermatogonium (diploid) undergoes mitosis
- Primary spermatocyte (diploid)undergoes meiosis 1
- Secondary spermatocyte (haploid) undergoes meiosis 2
- Spermatids undergo spermatogenesis
- Spermatozoa is formed and moves into epididmus
What is the function of sertoli cells?
- Maintains the blood testis barrier
- Provides nutrients
- Moves developing aperm towards lumen
- Secretes testicular fluid for sperm transport
- Phagocytosis in the vas defrens
- Produces androgen binding protein (ABP)
- Creates inhibit to initiate a negative feedback loop of FSH
8
When does meiosis occur in males?
Puberty
Why does the sertoli cell have a blood testis barrier?
Meiosis into a hapliod cell makes the sperm a foreign body. The blood will detect it as foreign and try to kill it with WBC
What are the 2 areas created from the tight junction in sertoli cells?
- Basal compartment (vascular)
- Alumina compartment (avascular)
What happens during spermiogenesis?
Cytodifferentiation occurs, for defective delivery of chromosomes into the oocyte
What happens during mitosis in a sertoli cell?
- Type A daughter cells stay in the basal membrane to maintain a pool of viable dividing cells
- Type B daughter cells move towards the lumen and create spermatocytes
Why is there a 15% difference of error between spermatocytes and oocytes?
Age of eggs
What happens to a spermatid during spermatogenesis?
- Becomes more streamline
- Grows a tail
- Loses excess cytoplasm
- Speratid elongates
What are the features of a sperm?
- Head with an cromosome cap (enzymatic knife) and nucleus
- Midpiece with mitochondria and olfactory epithelium
- Tail
Is the HPG axis the same in men and women?
Yes
How does the HPG indirectly stimulate spermatogensis?
Causes sertoli cell to release ABP which concentrates testosterone
What does LH stimulate and why?
Stimulates Leydig cells to secrete testosterone
How is testosterone created in leydig cells?
From cholesterol being processed in their smooth ER. This enables gonad production
What stages of males life is there a testosterone surge?
3-9 months before birth
Puberty until about 60, then starts to wa e slightly
How does the oocyte move from ovum to fallopian tube?
It is swept up by cilia on fimbrae and moved into the infundibulum of the fallopian tube
Where is an oocyte fertilized in the fallopian tube?
In the ampulla, it is now a zygote
Where does the zygote travel after the ampulla
Through the isthmus and into the uterus
What facilitates egg transfer across the fallopian tube?
Cillia and muscular contractions
Where does capacitation occur in the fallopian tube?
In the isthmus
What areas of the fallopian tube support embryonic development?
Ampulla and isthmus
How does ovulation affect the beat frequency of the fallopian duct?
High oestrogen increases beat frequency of cilia and smooth muscle contraction
Where does the zygote stop after fertilisation?
It halts in the ampulla until the ovary moves into the luteal phase. This creates increased progesterone
What happens if there is high levels of P⁴?
Decreases beat frequency and relaxes the smooth muscle
Why is there a halt of the zygote in the ampulla?
To allow the early embryo grow to be ready for implantation
What hormone does the cumulus cells secrete?
Progesterone
What are the functions of the epidimus?
- Matures sperm cells
- DNA stabilization
- Chromatic condensation and concentration
What are the seminal vesicles?
70-75% alkaline and fructose rich solution to feed spermatocyte
What are the 3 glands of the male reproductive system?
- Seminal vesicles: nutrients
- Prostate: enhances sperm motility, antimicrobial, proteases
- Bulbo-urethral glands: secretes mucus and neutralizes acid from urethra due to urine
What is the pathway of sperm?
- Ducts vans defrens
- Ampulla of ducts defrens
- Ejaculated duct
- Urethra
What is seminal plasma?
The non sperm component to create an alkaline environment, neutralizing the acidic vagina
What is the role of fibrinogen in ejaculation?
It coagulates the ejaculate to create a sperm deposit in the vagina
What is the role of seminal plasma?
- To create fibrinogen for ejaculate clotting
- Coat sperm with capacitation inhibitors
- Activates and augments motility of sperm cells
- Supplies nutrients for ATP production
- After 15-20 minutes the enzyme fibrinolsin fluidises the ejaculate by breaking down fibrinogen
What is the anatomy of the penis?
- 3x longitudinal columns of erectile tissue
- Corpora cavernousa
- Corpus spongiosum
- Dorsal vessels and nerves
- Deep arteries
- Spongy urethra
Why does the penis become erect?
- The engorgement of corpa cavernosa via vascular and neurological events
- Non distensible connective tissue causes stiffening
What tubes are active during ejaculation?
- Vas defrens
- Prostate
- Seminal vesicles
- Smooth muscle
- Seminal glands
What happens to sperm during their journey to fertilisation?
- Swim 16-20cm to ampulla
- Most either: fall out, killed by acid, die on the way or get lost.
How does the uterus aid sperm transport?
- Endometrial secretion provides nutrients
- Changes mucus consistency to be more fluid to enable easier transport (decrease P⁴=decrease mucus viscosity
- Aids capacitation
How does the oocyte attract the sperm?
By releasing chemoattractants a s P⁴ (created by cumulus cells), which the sperms olfactory epithelium picks up.
What happens to sperm in the isthmus?
Sperm binds to the isthmus to complete capacitation and synchronizes timing between egg and oocyte for arrival to the ampulla
Why is capacitation needed?
The non-covalently bound epididymal/seminal glycoproteins and sterols (cholesterol) means that the sperm can’t fertilise the egg.
Capacitation removes these from the head of the sperm.
What happens to sperm motility during hyperactivstion during capacitation?
It increases motility
Why is the female reproductive tract ideal for capacitation?
- High acid environment
- Proteolytic enzymes enable sterol-binding albumin
- High ionic strength increases colubikity to dissolve factors from sperm
Explain fertilisation
The acrosome reaction is initiated by the sperm contacting the Zona pellucia. The acrosome swells and multiple points of fusion occur between the outer acrosomal membrane and plasma membrane. The contents of the acrosome is released, inclusive of proteolytuc enzymes.
This enables the sperm to bind with thr plasma membrane of the oocyte
Explain fertilisation
- Acrosome reaction:sperm contacts Zona pellucida and Acrosome swells
- Multiple sites of fusion occur between plasma membrane and outer acrosomal membrane
- Acrosome bursts, contents such as proteolytic enzymes are released.
- Fusion between and oocyte occurs
What is Zona pellucida in an oocyte?
An acellular glucoprotein coat around that is synthesis and secreted by the oocyte
What is the purpose of the Zona pellucida?
Means the oocyte is viable for 12-24 hours after ovulation and enables fertilisation
Describe the process of acrosome reaction ans sperm penetration
- Hyalurondiase on head of sperm digests matrix between cumulus cells, exposing the Zona pellucida
- Sperm binds to Zona pellucida receptors triggering Ca2+ channels to open on sperm (catsper channels) triggering hyperactivation and acrosome reaction
- Acrosine is released which digests the Zona pellucida (can be done by multiple sperms)
- First sperm successfully inside chemotaxis’ to ooleme and binds
- Only centrioles enter oocyte and a membrane block occurs due to the sperm binding receptors shedding from oocyte membrane
- A corticol reaction occurs. Where Ca2+ surges from intracellular ER triggering cortical granules to fuse to oocyte plasma membrane and undergo exocytosis into the Zona pellucida.
- This causes zona reaction: a hardening of the Zona pellucida and destroys the Zona pellucida binding receptors
What is a Ca2+ spiking pattern?
A spike of Ca2+ over a couple of hours after ejaculation to facilitate fertilisation
What is the result of the Ca2+ spikes?
- Resumption of meiosis 2 “oocyte reaction”
- Hardening of Zona pelucia
- Preservation of euploid
What is the process of fertilisation?
- Meiotic division completes: Ovum and 2nd polar body formed due to Ca2+ spikes
- Formation of male and female pronuclei
- DNA from each pronuclei replicate, moves together and forms a mitotic spindle - nuclear envelope
- Maternal and paternal chromosomes combine to form a diploid zygote
- Fertilisation!
How long after fertilisation does pronuceli form?
4-7 hours
What does the sperm contribute to fertilisation?
Centrioles during spindle formation during cytokinesis
What does the oocyte contribute to fertilisation?
- Cell membrane
- Cytoplasm
- Organelles
- Mitochondria
What is preimplantation?
- The movement of the embryo through the fallopian tubes to the uterus
- Cleavage of the zygote to form bkastomeres occurs at this time too
What is clevage?
Rapid mitotic division of zygotes within the Zona pellucia
Why does cleavage occur I na zygote?
To increase surface area of the zygote to increase nutrient and oxygen uptake, and waste disposal
What does a blastomere turn into after creating about 16 cells?
A morula
What is a morula?
A solid ball of cells within a zygote
What are the 5 stages of embryonic development?
- Zygote
- 4 cell stage
- Morula
- Early blastocyte
- Mature blastocyte
What’s the difference between early and mature blastocyte?
Mature doesn’t have Zona palucia
What is the structure of an early blastocyte?
- Zona pellucida
- Trophoblast
- Embryoblast
- Blastocyte cavity
What are the 5 stages of blastocyte implantation?
- Day 4: early blastocyte hatches from Zona pellucida, floats around for 2-3 days then attaches to the endometrium (nutrients from uterine fluid and glands)
- Day 6-7 implantation: trophoblast cells adhere to endometrial epithelium. Inflammation initiated
- Day 7: invasion: trophoblast invades uterine wall, proliferates and differentiates into cytotrophoblast (inner) and syncytiotrophoblast (outer
- Day 9 continuation: embryoblasts differentiate into 2 layers: epiblast (foetus) + hypoblast (yolk sac) = embryonic disc
- Day 11-12 complete: blastocyst completes invasion, cells close over of endometrium, corpus luteum maintained by human chorionicgonadotropin ( hCG)
What is a cytotrophoblast?
A group of cells that have differentiated from trophoblasts to surround the blastocyte. Has minimal influence on placental development
What is Syncytiotrophoblast?
Differentiated cells from trophoblast that has invaded the endometrial wall, creating the placenta
What are the 2 types of contraception?
- Hormonal
- Non hormonal
What are the different ways of administering contraception?
- Oral
- Injection
- Implant
- IUD
- Condom
Hiw does the combined oral contraceptive work?
- High plasma oestrogen causes a negative feedback loop but doesn’t cause a LH surge.
- Inhibits secretion of FSH which stops maturation of follicles, so no ovulation
Hiw does progestin work for contraceptives?
Inhibits the synthesis of of LH via negative feedback loop. This stop the surge that triggers ovulation
How do both types of oral contraception work with the hypothalamus?
They reduce the production of GnRH, which reduces LH and FSH
What does high levels of progesterone do to the cervix?
Creates a thick mucus, which forms a plug. This prevents sperm gaining access to the uterus
What does high levels of oestrogen do to the uterus?
Creates a watery mucus which enables smooth travel to the uterus
How does the oral contraceptive work?
Through monophonic spikes, which is why they need to be taken daily.
What are the non oral, hormonal contraceptives
- Vaginal ring
- Injection
- Implant
- Hormonal IUD
What is a LARC?
Long Acting Reversible Contracteptive
E.g. implant, injection, IUD
What are the non hormonal contraceptives?
- Condom
- Copper IUD
What are common causes of infertility in women?
- Endocrine abnormality (hypothalamic dysfunction/pituitary disease)
- Ovarian dysfunction (PCOS, abnormal follicle development, pre azure ovarian failure)
- Implantation abnormality (Luteal phase deficiency, reduced progesterone production, delayed maturation of endometrium)
What is the most common endocrine disorder?
Poly Cystic Ovary Syndrome
How does PCOS cause I fertility?
Disrupts follicle development from early antral phase and arrests so the theca cell hyperproliferates, creating a lot of androgens (more testosterone)
What metabolic features cause infertility in both sexes?
- Increased obesity
- Insulin resistance
- Type 2 diabetes
- CVS diseasesemesters?
- Stress
- Smoking
- Alcohol
What anatomical abnormalities can cause infertility?
- Tubal disease: inflammatory scarring (STIs, pelvic inflammatory disease)
- Septic abortion
- Surgery
- IUD scalpinitis
What is endometriosis?
An abnormal growth of endometrial outside of the uterus
What are the symptoms of endometriosis?
Pain and bleeding due to tissue reacting to hormones same wY it would in the uterus
10% women
What are the causes of infertility in men?
- Varicole:dilation of pampiniform plexus (increases temp. Reduce sperm quality)
- Vas defrens blockage
- Retrograde ejaculation
- Hypogonadaltropic hypogonadism (Kallman syndrome)
- Sperm count, motility, structure, stickiness
What is the most common cause of infertility?
A woman’s age
What is AMH?
Antimullerian Hormone: produced by granulosa cells in primary, secondary and antral follicles.
This inhibits excessive activation of primordial to primary follicles
What does blood tests and ultrasounds check for regarding infertility?
- PCOS
- Endometriosis
- Ovulation
- Fibroids
- Polyps
- Ovarian cysts
- AMH
How can semen to analysed to determine fertility?
- Count
- Motility
- Morphology
- Volume
- Consistency
- pH
- Leukocytes
- Fructose levels
What is ART?
Assisted Reproductive Technology: manipulating both soerm and egg in lab and returning to woman
1 in 25 are art babies
What is IVF?
- Hormones given to woman in controlled manner to hyperstimulate ovulation.
- About 8 embryos are collected by flushing out the uterus with warm media
- Put into diskh with capacitated sperm and placed back to woman after 5-6 days
What Is ICSI?
IntraCytoplasmic Sperm Injection: male infertility, 1 sperm injected directly to egg
Indicating increased risk of health to children
How are hormones controlled in ART?
- Daily injection of FSH to increase follicle growth (ultrasound monitored)
- Injection of LH to induce resumption of meiosis in oocyte (36-40 hours after injection
- GnRH agonist given continuously prior and during gonadotropin to suppress natural ovulation
- Progesterone given during luteal phase to support embryo after transfer
What are the contraindications to ART?
- Ovarian Hyperstimulation Syndrome (OHSS)
- PCOS
- Fatal
- Multiple borth rate
- Preterm delivery
- Low birth weight babies
- Miscarriage or no pregnancy (20% livebith)
- Costly
- Emotionally draining