Flashcards in Reproductive System Deck (392):
What are the benefits of sexual reproduction?
Production of new individuals and mixing of genotypes to create genetic diversity.
Why is infertility becoming more common?
Cigarette smoking (can cause erectile dysfunction and poor sperm)
Increasing age at childbearing
How many couples does infertility affect?
1 in 7
Name two assisted reproductive techniques (ART). What percentage of babies born in most Western countries are by ART?
In vitro fertilisation (IVF)
Intracytoplasmic sperm injection (ICSI)
Describe the production of spermatozoon and the fertility in males over life.
Describe the fertility of females over their lifetime.
Constant production at ~300 million per day from puberty.
Constant fertility. Gradual decline with age.
Cyclical fertility from puberty, 3-5 days per month.
Compare the number of follicles in utero and the number that will be ovulated.
In utero, 7 million follicles, declining to near zero at menopause, only ~400 follicles will be ovulated.
Compare the sizes of sperm and eggs.
Sperm: smallest cell in the body
Egg: largest cell in the body
What is the rate of production of sperm per testicle? Compare the weights of sperm and eggs.
1500 per second per testicle
175,000 sperm weigh as much as one female egg.
How far must sperm swim to reach the egg?
List the endocrine glands controlling the reproductive processes. What happens with regard to the endocrine system when puberty starts?
- Hypothalamus, pituitary, adrenal glands, testes and ovaries
- Activation of the hypothalamic-pituitary axis and production of hormones.
What are the two main functions of the gonads?
Produce reproductive hormones
What does testosterone bind to in the body?
Cells with an androgen receptor
List the main water soluble reproductive hormones.
Gonadotrophin releasing hormone (GnRH)
Follicle stimulating hormone
Water soluble hormones are usually _______ and ________
What is the site of secretion of GnRH?
What is the site of secretion of FSH and LH?
What is the site of production and secretion of oxytocin?
Secretion: Posterior pituitary
List the main lipid soluble reproductive hormones.
Lipid soluble hormones are _______ _________
What are the two main types of androgens?
5 alpha dihydrotestosterone (more active form)
What are the three types of oestragen?
What is the one type of progestagen?
Oestradiol (most potent)
What are steroid hormones made from? What percentage of steroid hormones are free?
Cholesterol - obtained from diet
2-3% free (able to diffuse into cells whilst bound hormones cannot)
Which is faster out of action due to water soluble hormones vs lipid soluble hormones?
Action due to water soluble hormones
If a person were to lose their pituitary gland, what would be the result?
They would be castrate: loss of all reproductive function
Compare the sizes of the posterior and anterior lobes of the pituitary
The posterior lobe is much smaller
Out of the hypothalamus and pituitary, which is part of the central nervous system?
What kind of arrangement is the hypothalamic/pituitary/gonadal axis? What is beneficial about this?
Hierarchical arrangement: allows signal amplification
What is the main function of the hypothalamus?
To act as a homeostatic regulator for reproduction, stress, body temperature, hunger, thirst, and sleep.
Why is the hypothalamus called a neuroendocrine organ?
It processes both neural and hormonal information.
What is another name for the posterior pituitary?
How are nerves situated between the hypothalamus and the posterior lobe?
The cell bodies are found in the hypothalamus and the long axon tracts extend down to the lobe.
What are neurosecretory neurones able to do?
How are the cell bodies of the neurosecretory neurones arranged?
- Can conduct a nerve impulse, and synthesise, carry and release neurosecretory peptide hormone.
- They are aggregated into nuclei.
Where are neurosecretory peptide hormones synthesised?
How do neurosecretory peptide hormones travel to the axon terminals?
What are neurosecretory peptide hormones stored as?
- In the cell bodies of the neurones situated in the hypothalamus.
- They travel bound to carrier proteins.
- Secretory vesicles
What do nerve impulses that travel along the axons of neurosecretory neurones trigger?
What are the two neurosecretory peptide hormones released from the posterior pituitary?
- Exocytosis of the secretory vesicles, releasing the peptide hormones.
- Oxytocin and antidiuretic hormone
What is another name for ADH?
Where are oxytocin and ADH synthesised and transported to?
- Hypothalamus, Posterior pituitary
Compare and contrast oxytocin and ADH.
Very similar structures (Both short and differ by 2 aa's) but remarkable differences in specificity of action.
What type of muscle contraction does oxytocin have a major effect on? Give examples.
What is secretion of oxytocin stimulated by?
Smooth muscle contraction
- Milk ejection
- Contraction of uterus during childbirth
Stimulation of nipples, hearing the cry of a baby or uterine distension.
What is oxytocin used to induce?
What is the function of ADH?
Acts on kidneys to retain water.
What is another names for anterior pituitary?
Describe how the hypothalamus is connected to the anterior lobe.
The nuclei and short axons of the neurones are found in the hypothalamus. Axons join with the capillary bed in the hypothalamus. A linking portal (humoral) system joins the capillary to secretory cells in the anterior pituitary.
Describe the mechanism for hormone release into the anterior pituitary.
Neurosecretory neurones synthesise releasing and inhibiting hormones in their cell body into vesicles which travel to the axonal terminus. In response to nerve impulses, these neurosecretory peptide hormones are secreted into the linking hypophyseal portal vessels.
How often do the signals for release of neurosecretory peptide hormones occur?
Once every 1 or 2 hours
What is a hypophyseal portal system?
A vascular arrangement in which blood flows from one capillary bed to another without going through the heart on its journey.
Why a hypophyseal portal system instead of a normal capillary system?
We don't want the hormones to get diluted in the rest of the body.
What do the releasing and inhibiting hormones act on in the anterior pituitary?
Act on specific secretory cells arranged in clumps at the termini of the portal blood vessel.
How many types of releasing hormone are there? Do they have a positive or negative effect on the secretory cells?
What do gonadotrophs produce?
The two gonadotrophins: FSH and LH
For the reproductive system, how does the hypothalamus affect the anterior pituitary?
It releases a positive acting hormone called Gonadotrophin releasing hormone. This causes the anterior pituitary to release FSH and LH. Sex hormones are released by the gonads which have a negative effect on the pituitary and hypothalamus.
List 5 types of secretory cells in the anterior pituitary.
Describe the release of hormones from the pituitary.
Pulsatile: not being released all the time. Hypothalamic secretions are released in discrete bursts, separated by periods of little or no secretion.
What does the pulsatile release of hormones prevent?
Receptor desensitisation and down-regulation
What receptors do FSH and LH bind to?
What do FSH and LH promote?
Receptors in the ovary and testis
The synthesis of sex steroid hormones and gametogenesis.
What does the FSH stimulate in females and males?
F: Growth of ovarian follicles
M: Growth of spermatozoan
What does LH stimulate in females and males?
F: Secretion of female sex hormones and stimulates ovulation
M: Stimulates production of testosterone
What is the main secretory product of the testis?
What is testosterone associated with?
The development and maintenance of male characteristics and fertility
What do androgens promote?
Male sex development
Out of testosterone and 5 alpha dihydrotestosterone, which is more active?
5 alpha dihydrotestosterone
Do females make androgens? What is its role in females?
Yes but to a much lesser extent than males. Important for sexual behaviour.
WHat is the main reproductive hormone of females?
What is the main role of oestrogens?
Development and maintenance of female characteristics and fertility.
What is the main site of oestrogen production?
The granulosa cells of the growing follicle (oestradiol).
When and where are the three types of oestragen produced?
Oestradiol: produced by follicles. Beginning at puberty to menopause, women produce it in great fluctuating amounts.
Oestrone: produced from adipose tissue throughout a woman and man's life. As a weaker oestrogen, it is important after menopause.
Oestriol: Made by the placenta prior to birth to allow the cervix to widen.
What does oestrogen control?
Female sex development
Regulation of the menstrual cycle
Growth of the endometrium
Bone growth (in both men and women)
Do men make oestrogen? What is it important for?
Yes in much smaller amounts. For bone growth and spermatogenesis.
Do men produce progesterone?
What is progesterone important for?
Preparation and maintenance of pregnancy
What is the major steroidal hormone made by the corpus luteum and placenta?
Where are leydig cells situated? Describe them.
Just outside the seminiferous tubule. They are triangular in shape and are not directly involved in the production of sperm, but without them, sperm cannot be made because they are endocrine cells.
What is found next to the leydig cell?
List the layers found in the seminiferous tubule from basement membrane to lumen.
Sperm cell or spermatozoon
Where is the only location for spermatogenesis?
Seminiferous tubules of the testes
When are all eggs made by in the life of a female?
3 months before birth
When does spermatogenesis occur?
Only occurs after puberty
What is the rate of production of sperm?
300-600 sperm/gram of testis tissue/second constantly
What are the tree phases to spermatogenesis?
1) Mitotic division
2) Meiotic division
What happens at puberty with regard to spermatogenesis?
The primary germ cells are reactivated
What is the name for the primary germ cells of spermatogenesis? Where are they found? What shape are they? What do they divide by?
Spermatogonial stem cells
On the basement membrane
What do spermatogonia divide by?
Why does one daughter cell remain undifferentiated when spermatogonial stem cells divide by mitosis? What happens to the other daughter cell?
To maintain the stem cell population.
The other daughter cell continues to divide by mitosis, forming spermatogonia. The spermatogonia continue to divide by mitosis.
Describe the first round of cell division of spermatogonial stem cells.
Asymmetrically because we need to leave one daughter cell behind on the basement membrane.
What is formed after mitosis of spermatogonial stem cells?
A chain of cells called spermatogonia
What happens after mitosis of spermatogonia?
What do we call the area down at the basement membrane?
The basal compartment
Where do mitotic divisions of the spermatogonia occur?
Basal compartment of the seminiferous tubules
How many chromosomes do spermatogonia have?
What do spermatogonia move between after the completion of mitotic divisions?
Adjacent sertoli cells
To the adluminal compartment of the seminiferous tubules
When they are in the adluminal compartment, spermatogonia are in very close contact with the _________ ______
Once the spermatogonia move from the basal compartment to the adluminal compartment, what do we refer to them as?
Spermatocytes are the first cells to undergo __________ cell division
The first cells that enter the adluminal compartment during spermatogenesis are called?
How many chromosomes do primary spermatocytes have?
What do primary spermatocytes undergo? What happens to the chromosome number during this process?
Meiosis I - the DNA content doubles so each spermatocyte still has 46 chromosomes.
What are the cells called at the end of meiosis I? How many chromosomes do they have?
Secondary spermatocytes. These have 23 chromosomes with two chromatids.
How do secondary spermatocytes divide? What does this give?
Very rapidly by meiosis II to give four spermatids each with 23 chromosomes.
Why is it difficult to see secondary spermatocytes?
Because meiosis II occurs very quickly.
Describe the shape of spermatids.
Still round cells and have a round morphology
What is the final process in spermatogenesis?
Spermiogenesis in which the round spermatids differentiate their shape and become spermatozoa (sperm).
What is another name for spermiogenesis?
Describe the movement of the spermatids as they undergo spermiogenesis.
Move from the adluminal compartment to the lumen
What occurs during spermiogenesis?
Round spermatids form a tail, mid piece and a head
What is the midpiece of the sperm packed with?
Mitochondria to produce energy
What does the head of the sperm contain? What is it covered by?
Covered by the acrosome
What is the acrosome?
A compartment filled with enzymes required for egg penetration.
What happens to the excess cytoplasm of the spermatid? How does this affect the shape of the sperm?
It is lost into a structure called the residual body that is phagocytosed by the Sertoli cells after the sperm leaves so that we don't waste the aa's and sugars.
Elongates the sperm.
Where is mature sperm found?
In the lumen of the seminiferous tubules.
Describe the process administering the production of FSH and LH.
GnRH produced by the hypothalamus is released into the portal blood system to the anterior pituitary where we find the gonadotrophs that produce two hormones: FSH and LH
How does FSH and LH travel through the blood?
It exits the anterior pituitary and enters the peripheral blood until it reaches the testes.
What does LH bind to?
Receptors on the surface of the Leydig cells
How does LH affect Leydig cells?
Causes them to produce testosterone.
What is testosterone important for?
Production of sperm and development of secondary sexual characteristics.
What is dihydrotestosterone important for?
Development of secondary sexual characteristics in males, in particular, baldness.
What type of cell does FSH bind to receptors on?
Where are sertoli cells found?
Inside seminiferous tuules in direct contact with spermatogonia.
How does FSH affect Sertoli cells?
Causes them to make proteins, in particular, androgen-binding protein.
What type of hormone is testosterone?
What is the function of androgen binding protein?
To move the testosterone and DHT around the body via the blood because these are lipid hormones that are insoluble in the aqueous blood.
How is DHT related to sperm production?
Some is secreted into the seminiferous tubule where it is bound to androgen binding protein and becomes trapped as it can no longer cross membranes. This creates a reservoir of androgens in the seminiferous tubules.
What happens to spermatogenesis if no testosterone is present?
The mitotic cell divisions still occur at the basement membrane, but the spermatogonia cannot progress through to spermatocytes and spermatids.
Give examples of secondary sexual characteristics.
- Pubic hair growth
- Deepening of voice
What are the general effects of testosterone on the body?
How is the production of sperm a negative feedback system?
Testosterone feeds back to the hypothalamus and turns down the production of GnRH.
Also acts at the level of gonadotrophs to reduce the production of FSH and LH.
How is the level of FSH separately controlled?
It causes Sertoli cells to produce a peptide hormone called inhibin. It travels via the blood to the pituitary to interact with receptors on the gonadotrophs to reduce the production of FSH.
What causes the production of GnRH?
Kisspeptin: a neurotransmitter that regulates the production of GnRH and probably the onset of puberty.
What is a common feature of infertile men?
A reduced sperm count
What are three types sperm defect that can cause infertility in men?
Oligospermia - reduced sperm
Azoospermia - no sperm
Immotile - cannot swim
What is the percentage of infertility in the general population?
What occurs in an IVF (in vitro fertilisation)?
Oocytes (1 or more) are harvested and fertilised ex vivo (implanted into woman's uterus).
How many motile sperm are required for IVF?
What does ICSI stand for?
Intracytosplasmic sperm injection
What happens in an ICSI?
A single sperm is collected using a micropipette and is injected with an injecting pipette directly into the oocyte which is held by a holding pipette. Sperm is pushed past the zona pellucida and into the cytoplasm of the egg.
What is beneficial about ICSI?
Sperm does not have to be motile
Can use sperm collected by biopsy from the testes.
Where are the testes located?
In the scrotum
When do the testes move to the scrotum in humans?
What is cryptorchidism?
When the testes do not descend. These people are infertile.
What is meant by cryptorchid?
What percentage of boys does cryptorchidism occur in?
What are the stages of movement of the sperm from the seminiferous tubules to the penis?
Produced in seminiferous tubules
Move into the rete testis
Into the epididymis
Into the vas deferens
To the ejactulatory duct
To the penis
Do sperm move or swim from the seminiferous testes to the penis?
Move: it is suspended in fluid and pushed through by the muscular tubules.
What is the epididymis?
A comma shaped organ that runs from the top pole to the bottom of the testes. It connects to the vas deferens at the bottom.
What is the epididymis important for?
What happens to the sperm in the epididymis?
Acquire the ability to be motile and to fertilise.
How long do sperm reside in the epididymis?
What does the epididymis reabsorb?
Liquid from around the sperm, making it more (100x more) concentrated.
Why is the concentration of sperm advantageous?
Makes sure that the maximum concentration of sperm is produced
The vas deferens are the major sites of _______ _________
How long do sperm take to travel from the proximal end of the vas deferens to the far end?
What is found at the end of the vas deferens?
A widened region called the ampulla of the vas deferens
How long are the vas deferens?
Describe the path of the vas deferens.
Run from the epididymis up and around the bladder and then back down to join the ejaculatory duct from behind the bladder.
Describe the ejaculatory duct.
Short duct that joins with the urethra
What is the major site of sperm storage?
The ampulla of the vas deferens
What is the fluid that is ejaculated called?
What are the components of the semen that are not sperm contributed by?
What type of glands are seminal vesicles?
What do seminal vesicles empty into?
The ejaculatory duct
Where does the ejaculatory duct join that urethra?
At the prostate.
How long is the urethra?
Where does it run from and to?
From the bladder to the end of the penis
What are seminal vesicles?
Secretory glands (not storage areas) that secrete a mucoid (sticky) substance.
What are the 5 properties/substances within the secretion of the seminal vesicles?
Fructose - energy source for sperm
What are prostaglandins?
Lipid hormones important for smooth muscle contractions. May induce contractions in the female reproductive tract.
Why is it important for the seminal vesicle fluid alkaline?
The prostatic fluid and the female uterine tract is acidic so it helps to buffer against these.
What happens to the seminal vesicle fluid and the prostate fluid after ejaculation?
Fluid from the seminal vesicles is mixed with fluid from the prostate. They form a coagulant which is important for holding sperm in the female reproductive tract.
What helps coagulate the seminal and prostatic fluid?
Clotting proteins in the seminal vesicle
What shape and size if the prostate?
A doughnut shaped organ about the size of a golf ball.
What passes through the hole in the middle of the prostate?
What does the prostate secrete? What does it secrete it into?
Secretes prostatic fluid into the urethra ahead of sperm during ejaculation
What are the 5 characteristics of the prostatic secretion?
Slightly acidic (pH 6.5)
Contains citrate (for ATP)
A milky colour
Phosphate and calcium
PSA (breaks down coagulum) and other proteases
What gives the milky colour to prostatic fluid?
Phosphate and calcium
What is PSA?
An enzyme called Prostate Specific Antigen
What is prostatic fluid neutralised by? How long does this coagulum last?
Seminal vesicle fluid
What is the function of PSA?
Breaks down the coagulum, thus freeing the sperm and allowing them to swim out of the vagina and up through the cervix into the uterus.
What does semen consist of in what proportions?
Seminal vesicle fluid 60%
Prostatic fluid 30%
Other secretions Small amounts
What is the pH of semen? Why?
Approx. 7.5, which is slightly higher than physiological pH because it is destined to neutralise the acidic conditions of the vagina.
How does semen vary between species?
Varies greatly in its volume and content
What is the volume of human ejaculate compared to boar ejaculate?
How much sperm does a human ejaculate contain?
At least 20 million sperm/mL
What are the three major structures of the penis?
1) Corpora cavernosa x2
2) Corpus spongiosum
3) Penile urethra
What are the corpora cavernosa?
Spongy tissue that fills with blood during an erection and expands to pack the penis and this causes the erection. It is the main erectile tissue
What is the corpus spongiosum?
Sits between the two cavernosa and around the penile urethra. Prevents occlusion during erection.
What is the human erection caused by?
Hydraulic pressure within the corpora cavernosa
What is the purpose of the penile urethra?
Conducts semen and urine
What causes the smooth muscle of the corpora cavernosae to relax?
Release of NO and Prostaglandin E1 due to sexual stimulation
Is the corpus spongiosum erectile (fill with blood)?
What does the blood fill during an erection?
The cavernous spaces of the corpora cavernosa
How many times blood does the erect penis contain compared to the flaccid penis?
What adds to the engorgement of the penis?
Reduction of venous outflow due to engorgement of the corpora cavernosa.
What does relaxation of the smooth muscle in the corpora cavernosa require?
Guanosine Monophosphate (cGMP)
What is cGMP?
A 2nd messenger that reduces intracellular calcium
What is GMP broken down by?
The enzyme phosphodiesterase, particularly type 5
How does viagra work?
It inhibits phosphodiesterase (type 5), leading to increased GMP, relaxation of the arteries supplying the corpora cavernosa and erection.
What is meant by benign prostatic hyperplasia? What are the consequences of this?
Excess growth of the prostate. This occludes the urethra, which causes difficulty in voiding the bladder. Eventually causes weakening of the bladder. This can cause urinary infections and kidney problems.
What is the prevalence of benign prostatic hyperplasia? It was the _____ most common surgical procedure in men.
What are the treatments for BPH?
Surgery to hollow out the prostate
Selective 5 alpha-reductase inhibitors
What action do selective 5 alpha-reductase inhibitors have?
They stop the prostate enlarging or they shrink it.
What enzyme converts testosterone to dihydrotestosterone?
How many more times potent is dihydrotestosterone than testosterone?
Give two 5 alpha-reductase inhibitors.
Finasteride and dutasteride
What drives the growth of the prostatic tissue in BPH?What is this called?
Androgen dependent growth
What is the second most common cause of cancer deaths in men after lung?
___% of all cancer cases in men are prostate.
Why is detection of prostate cancer increasing dramatically?
Because of PSA testing: this test looks for PSA, which breaks down coagulant in the female reproductive system. It turns up in the blood when the male has prostate cancer.
Why have we not adopted a screening programme for prostate cancer despite it being cheap?
Deaths are increasing less dramatically than detection.
Autopsy cancer: 30% of men >50 years old have prostate cancer at autopsy, but only 9.5% have been diagnosed with prostate cancer. So 66% of the men didn't know they have prostate cancer and it isn't causing any problems.
What are the 4 ways prostate cancer can be treated?
1) Watchful waiting
2) Androgen depletion
3) Inhibition of testosterone action by blocking the androgen receptor
4) Surgery - prostatectomy
What can cause androgen depletion?
- 5 alpha-reductase inhibitors such as finasteride
- Inhibitors of androgen synthesis
What is a disadvantage of the screening test?
Many false positives
For 100 men undergoing prostatectomy, how many will die as a consequence of the operation, how many will have erectile dysfunction and how many will have urinary incontinence?
- 1 will die
- 20-80 men with erectile dysfunction
- 4-21 will have urinary incontinence
How is ovarian function different from the testes?
Cyclical activity from puberty to menopause. Few oocytes are released (~400). Mature oocyte is released every 28 days.
List the 4 female reproductive organs.
Uterine (fallopian) tubes
What angle does the uterus sit at compared to the vagina?
What is found at the bottom of the uterus?
What is meant by anteflexion and retroflexion?
A: Uterus faces the front of the woman
R: Uterus faces the back of the woman
What percentage of women have a retroflexed uterus? What complications can this cause?
May cause some pain during menstruation or intercourse
What are fimbriae?
Fingerlike projections of the uterine tube.
In humans, where is the semen deposited?
Outside the cervix, only a few percent can get past the cervix, where they are stored in the isthmus.
What causes the meeting of the sperm and egg?
Signals from the egg cause the sperm to meet with the egg in the ampulla?
What is the vagina?
An elastic muscular tube extending from the cervix to the exterior of the body.
How long is the vagina?
What are the three main functions of the vagina?
1) Serves as a passageway for the elimination of menstrual fluids.
2) It receives the penis during intercourse and holds spermatozoa before they pass into the uterus.
3) It forms the lower portion of the birth canal through which the fetus passes during delivery.
What shape and weight is the uterus?
A small, pear-shaped organ that weighs 30-40 grams
What is the fundus?
The top, dome shaped region of the uterus.
What is the internal and external os
Constrictions that lie above and below the cervix.
Most of the time, what stops bacteria and sperm from passing the cervix? When are they able to?
A plug of mucous in the cervical channel.
3-5 days before ovulation
What can be used to predict fetal growth?
What is fundal height?
A measurement of the distance between the top of the uterus and the pubic bone.
What does the fundal height correspond with?
The number of centimeters is approximately the number of weeks gestation.
What is fundal height increased with?
What is meant by breech birth?
Baby is the wrong way
What is gestational diabetes?
The baby is getting to much sugar and is growing faster than normal
What can reduced fundal height indicate?
Small baby or interuterine obstruction
What are the 4 functions of the uterus?
1) Pathway for sperm transport
2) Provides mechanical protection, nutritional support and waste removal for the developing embryo and fetus
3) Contractions in the muscular wall (myometrium) of the uterus are important in ejecting the fetus at the time of birth.
4) Source of menstrual flow.
What does the myometrium contract in response to?
What is the endometrium subdivided into?
Inner functional zone (stratum functionalis), that contains most of the uterine glands.
Outer basilar zone (stratum basalis), which attaches the endometrium to the myometrium.
Which layer is lost as part of the menstrual flow?
Where does fertilisation typically occur?
What type of environment does the uterine tube provide?
Provides a rich, nutritive environment containing lipids and glycogen, for spermatozoa, oocyte, and the developing embryo
Following ovulation, what is the oocyte drawn into the uterine tubes by? How does it do this?
Cilia on its surface use suction to pick up the oocyte.
Describe the epithelium lining of the uterine tube.
Has both ciliated and non-ciliated secretory columnar cells.
What is the mucosa of the uterine tube surrounded by?
Concentric layers of smooth muscle that contract to help the movement of the embryo.
What does transport along the uterine tube involve a combination of?
Both ciliary movement and peristaltic contractions
What is an ectopic pregnancy?
When the fertilised embryo is implanted in any tissue other than the uterine wall.
Where do most ectopic pregnancies occur?
In the uterine tube
How does smoking increase the chance of ectopic pregnancies
Cilia do not beat as well so chance is doubled.
What are the three risk factors for ectopic pregnancies?
Advanced maternal age
Prior tubal damage (due to chlamydia)
Where does the ovary sit?
High up in the pelvic cavity
What is the shape and weight of the ovaries?
Ovarian tumours are usually _________ tumours
What are the three distinct regions that the ovary is comprised of?
1) Outer ovarian cortex containing the ovarian follicles
2) Central ovarian medulla consisting of ovarian stromal and steroid producing cells
3) Inner hilum (hilus) which acts as a point of entry for nerves and blood vessels
Most of the ovarian cortex of a young woman is filled up with _________ ________
What is a primordial follicle?
An oocyte surrounded by a single flattened layer of follicular (in future granulosa) cells.
What is a primary follicle?
A bigger cell than the primordial follicle. Immature primary follicles consist of only one layer of cuboidal granulosa cells.
What is another name for primary follicle?
State the difference between follicular and granulosa cells.
What do oocytes secrete to form?
Glycoproteins, which form a translucent acellular layer called the zona pellucida?
What do sperm bind to on the oocyte?
The zona pellucida
What does the zona pellucida prevent?
The entry of sperm from another species
What exists around the granulosa cells?
Coming from the medulla, a condensation of ovarian stromal cells known as thecal cells.
What happens to follicles in response to FSH?
They get larger, producing many layers of granulosa cells surrounding the oocyte.
As granulosa cells proliferate, what do they produce?
A viscous follicular fluid that coalesces to form a single follicular antrum.
What distinguishes a secondary follicle from a primary follicle?
The presence of an antrum.
What is another name for a secondary follicle?
An antral follicle
What is the purpose of the antrum?
Provision of nutrients for the growing oocyte.
Apart from the formation of the antrum, what else occurs during the progression from the primary to secondary follicle?
The innermost layer of granulosa cells becomes firmly attached to the zona pellucida.
What are the firmly attached granulosa cells to the the zona pellucida called?
What is the mass of loosely associated granulosa cells called? Where is it found?
Outside of the corona radiata
What are the two layers that the theca develops into? What are they found within?
Inner glandular, highly vascular theca interna, and the surrounding fibrous capsule, the theca externa.
How is the theca interna involved with hormones?
Cooperates with granulosa cells to produce reproductive hormones such as oestradiol.
What are two other names of the mature follicle?
Graafian or pre-ovulatory
How is the mature follicle different from the secondary follicle?
It is larger because the follicular antrum grows. The oocyte becomes suspended in follicular fluid. It is connected to the rim of peripheral granulosa cells by a thin stalk of granulosa cells.
What happens as the follicle continues to develop after the mature follicle?
The size of the follicle continues to increase and its position in the cortex of the ovarian stroma causes it to bulge out from the ovarian surface.
What happens during ovulation?
The follicle ruptures, carrying with it the oocyte and its surrounding mass of cumulus cells.
What word is used to describe the exit of the ovary from the follicle?
What is the oocyte collected by after ovulation?
By the cilia on the fimbriae, which sweep the cumulus mass into the uterine tube.
What occurs inside the ovary after ovulation?
The antrum breaks down, the basement membrane between the granulosa and thecel layers break down and blood vessels invade.
What do granulosa cells form after ovulation? What is this process called?
Large lutein cells called the corpus luteum.
What is meant by lutein?
What is meant by corpus luteum?
What is the function of the empty follicle?
Secretion of progestagens, especially progesterone.
What happens to the corpus luteum if there is no embryo?
It will slowly dissolve. It loses its yellow pigment and the whitish scar tissue is called the corpus albicans (white body). It is absorbed back into the stromal tissue of the ovary over weeks to months
If the oocyte is fertilised and begins to divide, what happens to the corpus luteum?
It persists past its normal 2 week life span.
What rescues the corpus luteum from degeneration? What is this produced by and when?
Human chorionic gonadotrophin (hCG).
Produced by the chorion of the embryo beginning about 8 days after fertilisation.
What is used in home pregnancy tests?
The presence of hCG in maternal blood or urine is an indicator of pregnancy
What are the two phases of the ovarian cycle?
Follicular phase: day 1 to ovulation
Luteal phase: Ovulation to menstruation
What hormone affects the follicular phase and the luteal phase?
What stages of the follicle occur in the follicular phase?
Mature (Graafian) follicle
What stages of the follicle occur in the luteal phase?
Mature (Graafian) follicle
Which stages of the follicles produce oestrogen (oestrodial)?
Mature (Graafian) follicle
Which stages of the follicles produce progesterone?
What is the effect of estradiol?
Causes proliferation of cells
What do we see in the levels of oestrogen and progesterone after ovulation?
Levels of oestrogen decrease and progesterone becomes the main hormone.
How long is the average menstrual cycle?
What are the three phases in the uterine/menstrual cycle?
3) Secretory (after ovulation)
Usually how long is each phase of the menstrual cycle?
Menstruation: 3-5 days
Proliferative: 14 days
Secretory: 14 days
Which phase of the menstrual cycle is the most fixed with regard to number of days? What is the second most fixed phase?
Which stage of the menstrual cycle is highly variable?
What are the two main functions of the female reproductive tract?
What is the first stage of the changes in hormone level during the menstrual cycle?
Corpus luteum regresses, oestrogen and progesterone levels reduce as corpus luteum dies, which causes increased FSH and LH
What is the second stage of the changes in hormone level during the menstrual cycle?
FSH stimulation leads to increased follicular growth. This occurs to a group of follicles, of which one usually dominates.
What happens if two follicles dominate?
When does the third stage of the changes in hormone level during the menstrual cycle occur? What happens?
About day 6-7
We see the selection of the dominant follicle and production of granulosa cells, with increased oestradiol.
What happens at stage 4 of the changes in hormone level during the menstrual cycle?
Oestradiol suppresses FSH and LH production in the pituitary.
Describe the steps leading to the trigger of ovulation.
1) High levels of oestrogens from almost mature follicle stimulates release of more GnRH and LH in a positive feedback system
2) GnRH promotes release of FSH and much more LH
3) LH surge brings about ovulation
What is the 5th stage of the changes in hormone level during the menstrual cycle?
Oestrogen levels rise by day 12. A threshold concentration of oestradiol is exceeded. If this is maintained for 36 hours, there is a temporary switch from a negative to positive feedback.
What is the 6th stage of the changes in hormone level during the menstrual cycle?
Oestrogen mediated positive feedback triggers a rise in GnRH, leading to an LH surge
What occurs during the 7th stage of the changes in hormone level during the menstrual cycle?
LH surge induces ovulation.
What is the eighth stage of the changes in hormone levels during the menstrual cycle?
Corpus luteum develops. Increased progesterone.
What happens in the ninth stage of the changes in hormone levels during the menstrual cycle?
Elevated progesterone levels inhibit GnRH, leading to decreased FSH and LH in a negative feedback system.
What happens in the final stage of the changes in hormone levels during the menstrual cycle?
Demise of the corpus luteum
When is a woman fertile?
3-5 days before ovulation
What is meant by sex determination?
Commitment of the gonad to a testis or an ovary
What is meant by sex differentiation?
The phenotypic development of genital structures due to the action of hormones produced following gonadal development.
How is sex determination controlled in mammals?
In males, sex determination is much more strongly controlled by _________ than in females.
The human has ___ chromosomes, ___ pairs of autosomes and __ pair of sex chromosomes.
What results if the Y chromosome is present vs not present?
Y chromosome: male gonads develop (testes)
Y chromosome absent: female gonads develop (ovaries)
In the early stages of development, the gonad is said to be __________
Bipotential: It can go either way
What are some other ways sex determination is controlled apart from genetics?
Clown fish: dominant male changes sex into a female
What provides the pathway for testes to develop?
The sex-determining region on the Y chromosome known as the SRY gene.
What does the presence of a testis determine?
The sexual fate of the embryo, against the basic feminine trend.
In the absence of SRY, the embryo develops into a ________
Describe the differentiation into a male.
The Y chromosome causes production of testicular hormones that imposes maleness against an inherent trend toward femaleness.
What on the growing embryo becomes the gonad?
A layer of cells on the genital ridge eventually becomes the bipotential gonad.
State whether the mullerian duct and wolffian duct belong to males of females.
Early in development, ___________________
Mullerian duct = female
Wolffian duct = male
Both structures are present
Describe the steps for the development of internal female genitals.
1) Ovary produces oestrogen and progestagen
2) Mullerian duct development
3) Development of internal female genitals from mullerian duct
4) Wolffian duct regresses by itself
Describe the steps for the development of internal male genitals.
1) Sertoli cells in the testes produce anti-Mullerian hormone.
2) This leads to Mullerian duct regression
1) Leydig cells of the testes produce testosterone
2) Leads to Wolffian duct development
3) Results in internal male genitals
What are the female internal genitalia?
Upper third of vagina
What are the male internal genitalia?
What is mullerian duct regression under the control of in males?
Anti-Mullerian hormone secreted by Sertoli cells.
What actively maintains the Wolffian ducts in males?
Testosterone secreted by the testes.
What does the Wolffian duct develop into in men?
Epididymis, vas deferens, seminal vesicles
When do the testes descend from its internal position in the scrotum?
Usually after the 7th month.
What does a male without descended testes have a risk of?
Infertility and testicular cancer
What does the descent of testes allow for?
When do the Wolffian ducts begin to regress in females?
From about 10 weeks
What do the Mullerian ducts persist and develop to five rise to in females?
The uterine (fallopian) tubes, uterus, cervix, and upper vagina
How does the development of the external genitals occur? What causes this?
Fusion of the urethral folds enclosing the urethral tube forming the shaft of the penis. Labioscrotal swellings fuse in the midline forming the scrotum. The genital tubercle (glans area) expands, forming the glans penis.
If the fusion to form the shaft of the penis does not occur properly, what may be a consequence?
The baby may urinate out of the side of the penis.
What is the name for the formation of the scrotum?
How does the development of the female external genitals occur?
The urethral folds and labioscrotal swellings remain separate, thus forming the labia minora and majora. The genital tubercle (glans area) forms the clitoris.
Describe the phenotype of a person with androgen resistance syndrome.
The person is XY, and has testes, but the genital ducts and/ or external genitals are female.
Describe the mutation that occurs in people with angrogen resistance syndrome.
Mutation in the androgen receptor gene which prevents androgen function. In the absence of androgen action, the external genitalia will appear female.
Do hormones play any part in differentiation of the female?
The physical, emotional and sexual transition from childhood to adulthood. The transition is gradual and is punctuated by well-defined events and milestones.
What are the two types of changes at puberty that occur in response to hormonal changes?
Following activity in the developing embryo to produce internal and external genitalia, what happens to the reproductive system?
It "goes to sleep" during childhood
When are the reproductive endocrine systems reawakened? What does this lead to?
Leads to full secondary sexual maturation with capacity for reproduction.
Plasma levels of gonadotrophins are very ____ during childhood until the initiation of events leading to puberty.
What is the first endocrine sign of puberty?
Increase in plasma LH levels. This si the result of an increase in GnRH release.
When does GnRH (LH and FSH) secretion occur?
In early puberty at night during sleep.
In late puberty, LH pulses also increase
What rises in response to the increase in plasma LH during puberty?
Level of sex steroids rises
List the changes that occur at puberty for females in order.
1) Breast development
2) Pubic hair growth
3) Height spurt
What is meant by menarche?
The first menstrual bleed
When does the first physical sign of secondary sexual maturation occur in females?
How does oestrogen secretion affect puberty in females?
Leads to the appearance of a breast bud, followed by the formation of a breast mound.
How does ovulation affect breast development?
Ovulation, with the subsequent progesterone secretion, leads to full breast development.
When does pubic hair development occur?
Usually within 6 months of the appearance of the breast bud at age 10-12
What problem may there be if pubic hair development occurs much before breast development?
An androgen problem
What is the development of pubic hair in response to?
Exposure of hair follicles to androgens
What is growth and epiphyseal closure stimulated by in both sexes?
G: Steroid hormones (oestrogen and androgen)
What is meant by epiphyseal closure?
When does growth spurt occur in females and males?
When does menarche occur in females?
Average age of 12-13 years
When does first ovulation take place?
Not until 6-9 months after menarche, because the positive feedback mechanisms of oestrogen have not developed.
When do regular ovulatory cycles become established?
1-2 years after menarche
List in order, the appearance of changes in males during puberty.
1) Growth of the testes
2) Growth of pubic hair
3) Growth of the penis
4) Height spurt
What is the first sign of secondary sexual development in males?
Enlargement of the testicles
What causes enlargement of testicles?
Leydig cells enlarging and secreting testosterone
When does penile enlargement occur with reference to testicular enlargement?
Within a year
What causes enlargement of the penis?
Conversion of testosterone to 5 alpha dihydrotestosterone
When does pubic hair growth occur in relation to testicular enlargement?
About 6 months after the beginning of testicular enlargement.
When does axillary hair and facial hair begin to grow in relation to pubic hair growth?
A: 18 months later
F: Later than axillary
What leads to pubic hair development?
Conversion of testosterone to 5 alpha dihydrotestosterone
What is meant by spermache?
The appearance of motile sperm
When is motile sperm seen in urine? What occurs soon after?
First conscious ejaculation
What is body shape in males and females determine by?
The differential affects of androgen and oestrogen
What trend is shown in the age at which females first menstruate?
Trend towards earlier menarche.
What must be attained before the activation of the hypothalamo-pituitary-gonadal axis can occur? What is the mean weight of girls at the beginning of menarche?
A critical weight must be attained
Why has attainment of a critical weight been achieved earlier?
Due to improvements in nutrition, health care, and social living conditions.
What does critical weight siginify?
Sufficient storage is required to sustain pregnancy and lactation.
What is meant by precocious puberty? What is it due to?
The appearance of the physical and hormonal signs of puberty before 7 years in girls and 9 years in boys.
Usually due to a GnRH dependent problem, often due to a CNS lesion or injury e.g. tumour in the hypothalamus.
What is considered delayed puberty?
The lack of appearance of the physical and hormonal signs of puberty at the age of 13 years in girls and 14 years in boys.
When does delayed puberty occur?
When the gonadotrophin signals from the hypothalamus and pituitary are inadequate for sex steroid hormone secretion.
What is menopause a consequence of?
The ovaries running out of follicles.
When does menopause occur?
Between 50 and 52 years of age
What does the last episode of natural menstrual bleeding signify?
The end of a female's reproductive life
Describe the decline of number of follicles in a woman's life.
During fetal development: 7 million
Birth: 1-2 million
Steady decline of follicles with puberty: 400000
What are the different phases associated with the end of reproductive life in women?
Pre-menopausal: 40-46 regular menstrual cycles
Menopausual transition of variable duration: 46-50 irregular cycles
Peri-menopause: After premenopause to before ovarian senescence
Ovarian senescence: ovary shuts down
What do we see in hormone levels one year after menopause?
The ovary has essentially ceases producing hormones.
Oestrogen production reduces to less than one-tenth of previous. Oestrogen (oestrone) arises mainly from production in the stromal cells of adipose tissue.
What is meant by ovarian senescence?
When the ovary stops producing hormones.
Oestrone is a ______ _________
What causes the menopausal symptoms?
Decrease in oestrogen
List the perimenopausal symptoms.
- Vasomotor: hot flushes and night sweats
- Genitourinary symptoms: vaginal dryness
- Bone metabolism: osteoporosis
- Behavioural/Psychological changes: depression, tension, anxiety, mental confusion, libido