Unit 1 - Parturition & Reproductive technologies Flashcards
What does Partuition require?
- Signal from foetus
- Cervical Softening
- Co-ordinated myometrial contractions
What occurs in stage one of Parturition? How long does this last?
(2-6 hours)
- regular uterine contractions
- cervical shortening and dilation occurs
What is a latent phase of cervical dilation? How is this different from active phase?
latent- slow dilation
active- rapid dilation
What occurs in stage two of Parturition? How long does this stage last?
(30-120 mins)
complete delivery of foetus, rupture of membranes and abdominal contractions
What occurs in stage three of Parturition? How long does this stage last?
(5-8 hours)
Delivery of placenta
What is hypertrophy in relation to Parturition?
oestrogen stimulates the muscle cell size to increase
How does the myometrium contract? (4 steps)
- spontaneous depolarizing pacemaker potential occurs
- when the magnitude of these potentials is higher than the critical threshold a burst of action potentials occur
- intracellular calcium increases in the extracellular fluid and endoplasmic reticulum
- the calcium binds to regulatory sites on actin & myosin, allowing expression of ATPase & causing contractions
What is Brachystasis?
Which cells undergo this process?
when contractions retract the lower uterine segment at the cervix to create a birth canal.
Myometrial cells
What is the junction between the upper and lower segments of a uterus called?
Retraction Ring
What is the role of hormones in Contractions?
Oxytocin lowers excitation threshold of muscle cells
Prostaglandins stimulate liberation of Calcium from intracellular stores
How is Oxytocin regulated?
What does it lead to?
- synthesised in the hypothalamus and transported axonally to the posterior pituitary.
- Released in response to the stimulation of the cervix by the foetus
Leads to..
Myometrial contraction (+ve feedback loop)
Prostaglandin release
What is the Fergusson reflex?
contraction initiated by pressure at the cervix or vaginal walls
What is Primary Uterine Inertia? What is is caused by?
failure to initiate contractions at start of parturition
caused by lack of oxytocin
What is secondary uterine inertia?
When is this most common?
uterine contractions at start, uterus then becomes fatigued and therefore contractions stop.
Common in large litters
Cervical softening involves what three things?
- reduction of collagen fibres
- increase in proteoglycan matrix fibres
- endocrine control
What hormone is involved in Cervical Softening?
Prostaglandins - breakdowns collagen & stimulate uterine contractions
What is Ring Womb?
What is it caused by?
failure of the cervix to soften despite uterine contractions being normal
Caused by -
lack of prostaglandin
also linked to selenium deficiency
How is a Vaginal/ Uterine prolapse treated?
Vulva suture, prolapse harness or cull after parturition
How is Parturition started in Sheep? [what hormones are involved?]
- Foetus becomes stressed and releases ACTH (adrenocorticotropic hormone) leading to cortisol increase
- Rise in cortical leads to decrease in progesterone
What is ART technology? What is the purpose of it?
Assisted Reproductive Technology
increase chances of fertilisation & achieve pregnancy
What are the 6 steps of IVF (in-vitro fertilisation)?
- Superovulation
- Egg retrieved from ovary
- Semen Collection
- Insemination & Embryo Culture
- Embryo Transfer
- Luteal Support
What does Superovulation mean?
What are some side effects of this?
ovary is stimulated to produce multiple follicles using FSH & LH
- IVF drugs linked to ovarian cancer (but infertile women are predisposed to develop cancer)
- ovarian hyperstimulation syndrome
How is an ultrasound used in IVF?
Hint- used mainly in egg retrieving
Use transvaginal ultrasound to monitor follicular development
oocytes are then aspirated by ultrasound guided catheter
Once an egg is fertilised in vitro (in IVF) it is allowed to mature up to…….
4-8 cell stage using maturation media
What does Luteal support in IVF consist of?
administration of medication (particularly those that help maintain the Corus Luteum e.g. Progesterone)
What is Intra-Cytoplasmic Sperm Injection?
modified IVF technique
sperm injected directly into oocyte so higher success rates
When is Intra Cytoplasmic Sperm Injection used?
If sperm is unable to fertilise due to abnormal morphology, motility or damaged acrosome
What is Pre- implantation Genetic Diagnosis?
screens embryos for genetic disease e.g. sickle cell anaemia, cystic fibrosis
What is the Method for Pre-Implantation Genetic Diagnosis?
- Patient undergoes a routine IVF treatment & embryo matures to 8 cell stage
- A sharp pipette is used to break through the Zona Pellucida to suck up blastomere (known as Zona Drilling).
- Blastomere is broken down to get the genetic content & test for markers of genetic conditions.
Why is Mitochondrial Donation performed before IVF in some cases?
defects in mitochondrial DNA affect how cells use energy
How does Mitochondrial Donation work?
- Remove the nucleus from a harvested oocyte
- Remove and discard the nucleus from a donors oocyte (healthy mitochondria)
- Insert the patients nucleus into the donor oocyte
- Fertilise the oocyte with sperm (IVF or ICSI) and implant into patient
What is gene editing?
form of genetic engineering, enables identification, removal and replacement of ‘faulty’ genes
What is CRISPR-Cas9?
restriction enzyme complex used in gene editing to edit human germ line
How does CRISPR-Cas9?
- Disable/ insert DNA into an embryo
- CRISPR RNA sequence is generated to reflect the sequence of a target gene using Cas9 as the restriction enzyme
- The CRISPR-Cas9 complex is introduced to the embryo
- The target sequence is snipped out of cellular DNA and the synthetic DNA can be introduced.
How can CRISPR-Cas9 be applied to agriculture/ farming?
Aqua Advantage Salmon- twice growth rate & consume less food Muscle Mass (Cows)- embryos edited to double muscle mass
How can gene editing be used in organ transplantation?
CRISPR-Cas9 can be used to remove disease (PERV- Porcine Endogenous Retrovirus) in pig kidneys and lungs
What is the uses of Stem Cell Transplantation in Infertility treatments?
Can introduce Spermatogonial stem cells (SSC’s) into a host testis when host does not make his own sperm or testis
What are the advantages of Stem Cell Transplantation in Infertility?
- preserve endangered species
- can be used to breed from an animal after its death
- reintroduce fertility in cancer survivors
How does Stem Cell Transplantation in relation to Infertility work?
[Spermatogonia stem cells divide asymmetrically- 1 cell enters spermatogenesis & 1 cell replaces the stem cell pool]
- Isolate the Spermatogonia using surface proteins
- Multiply these in cell culture
- Transplant the stem cells into the testis via the rete testis or vas efferentia.
