Review #1 Flashcards
(35 cards)
what is important in ET for the donor cow? the recipient?
donor: genetic merit
recipient: reproductive health, normal estrus cycle, sanitation
What happens to fertility in the summer?
fertility decreases because cows get hot when they are stressed
AI in pigs
when you remove the sow from her piglets she enters the estrus cycle again
always use fresh semen
Is the estrus cycle important for IVF?
no
Is it preferable to freeze the semen?
no because frozen semen is less viable than fresh semen
how much do you inseminate a cow with?
20 million sperm 250 microliters
Do all cows respond to estrus synchronization (superovulation)?
no, so you will need to use multiple cows
In ET does the recipient get superovulated?
no
How does flushing work?
can do both horns at the same time or one at a time. give cow epidural to relax, flush multiple times, use a filter to concentrate embryos
does the frequency the protocol is repeated have an effect on the ability of the cow to produce embryos?
nope
what is necessary in the recipient to receive the embryo?
needs a CL, so progesterone can maintain the pregnancy. Embryo is placed in the same uterine horn as the ovary with the CL. They talk to each other and pregnancy will be maintained. Use ultrasound to find the CL
advantages to IVF
-can collect and use oocytes from cows that are too young or too old
what do cortical granules do?
change the charge of the ZP and the sperm receptors to prevent polyspermy
what media do we use in cryopreservation?
glycerol. It kicks out the water, so crystals don’t form and burst the embryos
what is a zygote?
fertilization until cleavage
how long does it take to do embryo transfer?
60 days
can do many more cycles of IVF in this time
what percentage of IVP embryos are viable
50% - in vivo is a bit better
In vitro we waste 50% of the oocytes because they won’t produce embryos
how do we improve efficiency of IVP?
- right now we are basing it off morphological change, which is not accurate
- However, monitoring how it changes over time - dividing at the right time, will give better info
ie the use of TLC and continuous observation we can choose the most viable embryos
how do we select good oocytes?
- select larger oocytes that are NOT actively transcribing
- Collect oocyte from a larger follicle (so larger oocyte)
- Can use FSH to push the follicles to grow and then collect them at the right time
culture conditions
- can use the sheep oviduct as a live incubator, cultured on the oviduct
- best conditions are in vivo
- IVC - the calves are larger, which complicates birth, piglets become smaller,
TLC and its purpose
time-lapse cinematography
used to monitor the development of embryos in vitro culture
-look at symmetry of the cell division and cytoplasmic fragmentation, blastomere number and then select embryos accordingly
what happens in oocyte maturation?
- Redistribution o fmitochondria–surround meiotic spindle and around lipid droplets
- Migration of cortical granules to cortex
- Reorganization of endoplasmic reticulum–build-up Ca reserves–readiness for fertilization
- Retraction/lost of transzonal projections(TZPs)
- Changes in transcription , translation, mRNA stability
- Changes in pattern of protein synthesis
regulation of CC functions
proliferation apoptosis metabolism expansion Luteinisation (cause production of the CL)
what are oocyte secreted factors
sent to the CC.
GDF9, BMP15
