Direct transfer in cattle

During the past 10 years vitrification has revolutionized human IVF by contributing substantially in the success of blastocyst culture, single embryo transfer and PGD/PGS.

However, in spite of the excellent results achieved under experimental conditions, the commercial application in cattle

is negligible. Direct transfer, a most convenient procedure widely used for traditionally frozen embryos is supposed to be impossible after vitrification.

However, it is not true.

There is a simple way to make in-straw dilution and direct transfer of OPS vitrified embryos. No lab, no microscope is required, a modified transfer straw filled with medium, a scissor and a water bath is enough - almost the same as for traditional in-straw dilution. All can be done on the farm, and requires approximately 1 min work per transfer (see below).

If yes - why not?

1. Most vitrification methods used in human IVF

are unsuitable for direct transfer.

The robust OPS technology is the best -

- also for this purpose

2. Commercial embryology is conservative,

does not like "risky" challenges

Why to use OPS vitrification and direct transfer in cattle?

1. It is simple and produces excellent quality embryos

2. High pregnancy rates can be achieved

also with OPU/IVF, doubling its overall efficiency

3. No need for expensive traditional freezers

See how easy it is (below)

we will provide you all required help,

if help will be required at all...

OPU/IVF was also disregarded for a decade a brave attempt was needed

What is needed?

1. Warming-transfer straw (part of our Direct Transfer Kit)

2. TCM Hepes (0.2 ml/straw) with 20% serum and 0.2 M sucrose

3. Water bath or a jar with warm water (39C) or a heated stage (39C)

4. Scissors

Preparation:

Fill the straw with the sucrose medium. Aspirate from the funnel end to the cotton

with air bubble

leave approx. 1 cm from the wide end empty

as shown on the picture

Keep it warm (vertically in the bath, or horizontally on the stage)

0 s

1-2 s

Warming

1. Place the straw vertically in front of a dark even surface (lab bench) for better visibility.

Hold it firmly, support your hand with the edge of the bench.

2. Remove OPS from liquid nitrogen by holding it with thumb and middle finger. The index finger should be in a convenient position for closing the thick end (later).

When the OPS leaves liquid nitrogen, start to count loudly: 1, 2...(approx. 1 s each)

Approach quickly the funnel end.

3 s

3. When you count 3, you should be inside the funnel. Touch the wall and proceed slowly.

4 s

4. When you count 4, immerse the end of the OPS into the warming medium, submerge the embryo-containing column in the OPS entirely.

1-2 s

5 s

7-10 s

5. When you count 5, just 1 s or even less after immersion, you will see solution ascending in the OPS because of the capillary effect.

If you see that, close the thick end of the OPS with your index finger.

Hold firmly, do not release! If the closure is airtight, the warming air in the OPS will press out entirely the solution into the warming straw.

6. When the air reaches the end of the OPS, but before air bubbles start to form,

lift and remove it slowly from the warming-transfer straw - while still holding firmly the end. Keep touching the inner surface of the wall with the tip, helps to get all solution - and all embryos - removed from the OPS.

No solution in OPS means all embryos are out. No microscopic control is required.

You may make transfer immediately, or after another 5-10 min incubation of the straw in water bath or on a heated stage (do not forget to cover it with a plastic box).

Just before the transfer, cut the funnel end of the straw (above the solution level) with decontaminated scissors.

NOTE: if solution remains in the OPS, you cannot repeat the same process again!

In that case, just add a syringe or a pipette to the open end of the OPS, and expel carefully the medium into the warming straw. You may also flush the end of the OPS with several pipetting.

(This is an emergency procedure for beginners, very rarely needed in routine practice.)

Please make a little practice, a few rounds of sham warming-expelling by using degenerated embryos.

Don't forget, you have to cool down OPS properly (10-15 min in liquid nitrogen) to be able to expel the content with the warming air inside - as above.