Conception & Sub-Fertility Flashcards
How much ejaculate does a male produce?
1.5-5ml
What is in male ejaculate?
- Seminal vesicles secretions: rich in fructose (nutrient), proteins, semen clotting factors, ILs and PG E
- Prostate gland secretions: PO4 and HCO3- buffers, PSA, coagulase (liquefying), zinc, citric acid, spermine, spermidine and putrescine
- Testicles and epididymis secretions: sperm, testosterone and L-carnitine (anti-oxidant affecting motility)
- Bulbourethral and urethral gland secretions: lubrication which can include anti-sperm Abs
What is the key characteristic of male ejaculate?
It is ALKALINE (pH 7.2) so must get out of the vagina quickly to survive the acidic environment
What concentration of white blood cells in the ejaculate indicates an infection?
> 5 million per ml
If a womens period is irregular, what phase is this usually in?
Follicular phase
What are the key characteristics of a mature human oocyte?
Oolemma
Ooplasm (contains nutrients)
Polar body
Zona pellucida
Arrested in metaphase II of meiosis ideally
What are the 4 main events which must happen to sperm that are essential for fertilization?
- Motility to swim against action of tubal cilia (perhaps by chemotaxis)
- Capacitation: changes to outer glycoprotein coat
- Sperm needs to get there before the egg or the egg will decrease in quality (have sex just before ovulation)
- Acrosome reaction to penetrate the oocyte’s zona pellucida
What female characteristic aids fertilisation?
Uterine contractions (not directly orgasm related although it is thought that this helps too)
What occurs in the process of fertilisation?
- Mature capacitated sperm meet the metaphase Ii oocyte in the ampulla of the oviduct
- Hyperactivation and acrosome reaction of sperm allows it to penetrate the zona pellucida and bind to oolemma
- Final maturation of oocyte and release of 2nd polar body
- Sperm entry and binding to oolemma causes Ca2+ transients that:
- Activate oocyte for further development
- Release cortical granules avoiding polyspermy
How does the movement of the sperm change as it moves through the female reproductive tract?
Starts by quickly moving forward in a straight line
Begins to thrash head aggressively when it gets to the egg to breach the zona pellucida (caffeine makes these movements occur too early so sperm do not get far enough)
What can happen if a fertilisation is dispermic?
Abnormal conceptus e.g. diploid
Possible abortion
What are the stages of embryo development?
- Pronucleate (6-20hrs)
- Cleavage (18hr-3dys)
- Compaction (3-4dys)
- Blastocyst (5-6dys)
- Hatching out of zona pellucida to interact with endometrium (5-7dys)
What occurs in embryonic genome activation?
mRNA inherited from oocyte supports embryo development through fertilisation and early cleavage and then mRNA production from the embryonic genome occurs principally at the 4-8 cell stage (but some transcription from pn stage) - oocyte has capacity for DNA damage repair
What arrests the oocyte at the 4-8 cell stage?
α -amanitin found in several species of the mushroom genus Amanita
Why is prediction of embryo viability difficult?
They are often mosaic in the early stages where individual blastomeres differ from eachother so there is differences between cells that are both genetic and biochemical
What is the inner cell mass?
Undifferentiated area that becomes the embryo with stem cell markers but making up the minority of cells (~20%)
What is the trophectoderm?
An invasive/adhesive structure that accommodates some abnormal cells (pre-natal diagnosis is via Chorion Villus Sampling) and secretes hCG
What occurs in implantation?
Immunologically complex process including apposition, adhesion and attachment occurs in the upper part of the uterus around 7 days after ovulation via specific orientation and maternal/embryonic communication mechanisms - difficult to study in humans
What is the most likely stage of failure of IVF treatment?
Implantation of embryo into uterus: 40% manage and 60% fail - if it manages failures after this stage only occur in ~15-20%
What is happening to the population of women having babies?
The amount of babies being born to women over 40 years old has more than doubled so the population of pregnant women is getting dramatically older
What is infertility?
1-2 years of attempting pregnancy occurring in ~ 1 in 6 Western couples
What is the average age of a women’s first pregnancy?
31 (35 for IVF patients)
What is the average age of menopause?
51 although fertility declines from 30 years declining rapidly at 37 years (bi-exponential fall of follicles in ovaries) and being very low from 40 years
What are the common causes of infertility?
Coital problems Endometriosis/cervical mucous Tubal damage Ovulatory failure Sperm problem Age Unexplained Combination
