These Applications Notes are offered for guidance only. They have been supplied to us by DB1 users. However, we can offer no guarantees of their effectiveness. Biotronics Ltd accepts no liabilities for losses incurred by use of these methodologies.
Seeding when Freezing horizontally
The diagram above shows the normal arrangement of media, plugs and embryo in a freezing straw. Three bolus of media separated by air with embryo in the middle bolus.
When freezing vertically with the straw seal down it is possible, although not desirable, to seed at the top of the embryo media bolus. The embryo is particularly susceptible to damage during vertical freezing because it falls to the bottom of the bolus and is near/in the air-media meniscus. At such an interface the zona is less protected. Incautious seeding can then result in zona damage. Controlled rate freezing with seeding is carried out to keep the "freezing shock" to the minimum. The closer the seeding to the embryo the larger the freezing shock.
When freezing horizontally the embryo will be in the middle of the central bolus. Seeding should only be carried out at the bolus near the label plug. The "Seed" will pass along the straw because as the media is drawn through the straw it will leave a small "trail" to transmit the seed. This results in the minimum of freezing shock.
