new technologies in assisted reproduction Flashcards
(43 cards)
what is the definition of infertility?
failing to get pregnant after 2 years of unprotected sex.
causes for infertility?
male - 30% female - 30% combined - 10% unexplained - 25% other - 5%
how many couples does infertility affect?
1 in 6 couples
what is the aim of assisted reproductive technology?
to bring the sperm and oocyte close together to increase chances of fertilisation and achieve pregnancy
what of the types of assisted reproductive technology?
IVF intra cytoplasmic sperm injection (ICSI) preimplantation genetic diagnosis mitochondrial donation gene editing
what is causing infertility in animals?
pollution
deforestation
rising global temperature
1/3 of male fish in UK rivers are feminised due to pollution events.
reasons people may want assisted reproductive technology?
infertility - female and male
absence of a partner (lesbian, gay transgender parent, single woman, death of spouse)
genetic engineering (eliminate hereditary disorders, sex selection, promote beneficial trades, generate transplant tissue, produce engineered species)
what are the steps in IVF?
super ovulation semen collection insemination embryo culture embryo transfer luteal support.
how is super ovulation achieved?
stimulation of ovaries to produce multiple follicles - manipulation of the hypothalamic pituitary gonadal hormone axis
- suppression of normal cycle using GnRH agonist
- high dose FSH and LH increase follicle number
what are the risks with super ovulation?
there are mild and severe effects
if drug regime is not ideal for the individual
- ovarian hyper stimulation syndrome - acute inflammatory condition that can be fatal
- IVF patients more likely to develop ovarian cancer - thought not to be from treatment but from original pathology.
what is the process of oocyte collection?
monitor follicular development by transvaginal ultrasound.
when there is 2+ follicles 16-18mm diameter
10000 IU hCG (LH like action) induces oocyte maturation
oocytes aspirated by ultrasound guided catheter
tell me about the process of sperm preparation and selection?
preparation - removal of seminal plasma, WBC and bacteria.
selection - sperm viability (motility - percale swim up, plasma membrane integrity, acrosome integrity), genetic characteristics (sex sorting)
what are the different ways of collecting sperm?
natural
electro-ejaculation (if men are unable to produce samples) - insert a probe into rectum next to the prostate gland - you get lots of seminal plasma but very few sperm as the testis are not being stimulated.
in animals you can use an artificial vagina
boar mate - a chemical which is the same as the pig male pheromone - they will mate with the woman because they think there is competition. It can also be used to see if woman are in oestrous
how can sperm viability be tested?
- basic sperm assessment: motility, morphology
- fluorescent staining assess viability
- plasma membrane integrity - DNA specific probe SYBR14 stains sperm with an intact plasma membrane green, DNA specific probe propidium iodine stains sperm with damaged membranes red.
- acrosome integrity - FITC PNA (peanut agglutin) stains outer acrosomal membrane green.
- assess using flow cytometry ( evaluates thousand sperm in a short time, measurements in real-time allowing continuous assessment in response to an experimental treatment)
how does flow cytometry work?
- sperm stained with fluorescent probes
- each fluorescent probe emits light at a specific wavelength when excited
- The flow Cytometer consists of: (a laser beam directed onto a stream fluid containing fluorescent labelled sperm, fluorescent detectors aimed at the point where the fluid passes through the laser)
- passage through the laser excites the fluorescent particles in the sperm causing them to emit light
- fluorescent detectors assess the number of sperm passing through the laser beam emitting light of a specific wavelength.
- Determine the proportion of membrane intact sperm
how can sex be sorted?
- it is a specialised type of flow cytometry
- sorts sperm into sub-populations based on fluorescent labelling
- one cell at a time
- FACS machine assigns electrical charge to sperm fluorescing at a specified wavelength
- sperm sorted by electrical charge
(routinely done in animals but can’t be done in humans) - common in pigs as testosterone makes pigs taste bad so farmers want females.
what is robotic sperm?
it is sperm controlled by magnets - a robotic addition to sperm
it has a corkscrew shaped motor
was created in germany 2016
been tested in bovine sperm and oocytes
drives sperm with abnormal motility
could be used to deliver drugs? - put drug in sperm head and drive it towards cancer.
when does cleavage occur in IVF?
embryo cleavage is 24 hours after IVF
what happened when bovine embryos were exposed to human maturation media prior to blastocyst stage?
large offspring syndrome
often fatal for mother and calf at birth
organ defects in surviving calf
when are the embryos from IVF transferred to the uterus?
2-5 days after IVF (4-8) cell stage
when are 2 embryos transferred?
in the UK if the woman are over 38 or if they have other risks.
how is the embryo transferred?
using a transfer catheter, with a trans-abdominal ultrasound to guid it
what can be done with excess embryos?
cryopreservation
need permission from both partners to use embryos
what are the success rate of IVF?
approximately 25%
