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oocyte and pipette
Equine Intracytoplasmic Sperm Injection (ICSI)

The ICSI procedure involves micro-injection of a single sperm cell into the cytoplasm of a mature oocyte, which physically causes fertilization. The fertilized oocyte is returned to an incubator and allowed to develop into an embryo, which usually occurs within 6-8 days. Because the preservation of semen is essential in many situations, we can talk to you about options for maximizing the use of semen. These options include refreezing sperm in small numbers in straws specifically designed for ICSI or cutting a small portion of a straw under liquid nitrogen.

Because ICSI utilizes a single sperm cell for each oocyte, this procedure holds tremendous potential for the production of foals using semen from stallions with low numbers of sperm or poor sperm quality.

Embryo Transfer Options

Embryos produced via ICSI can be 1) transferred into a recipient/surrogate mare right away, or 2) transferred back into the donor mare (auto-transfer), 3) vitrified (frozen) for transfer at a later date (see below),

Fresh transfer of embryos into recipient mares

CSU ERL manages our own leased recipient herd and embryos produced in our ICSI lab can be transferred (pending maturity) into a synchronized recipient mare. If the mare owner elects to use CSU ERL recipient mares, this service must be selected at the signing of the ART contract to ensure proper communication and synchronization of mares. All CSU ERL recipient mares are managed by the Mare Service team, led by Dr. Patrick McCue. Embryos can also be shipped to another embryo transfer station. Mare owners should contact their embryo transfer station ahead of time to complete appropriate contracts and provide a copy to the ART service. Communication to synchronize the recipient mare is of the upmost importance.

Auto-transfer back into donor mares

Many mare owners have a young, healthy donor mare that they would like to have carry her own ICSI produced pregnancy. This type of embryo transfer is called an “auto-transfer”. This option is primarily used with young, healthy, fertile mares that have no history of dystocia or problem pregnancies. If your mare is suitable to carry her own pregnancy this maybe an option and will need to be identified prior to the initiation of services.

Embryo Vitrification & Storage of Embryos

Embryo vitrification can be used as a means to cryopreserve (freeze) embryos from donor mares to be used at a later date. The procedure is very successful with small embryos. Once embryos are vitrified, they are placed in liquid nitrogen and can be stored indefinitely. Vitrified embryos can be warmed and transferred at a later date selected by the embryo owner. Prior to warming and transfer, embryo owners will receive a letter from CSU. This letter will ask for the desired month of warming/transfer and for those with multiple embryos, the number of embryos to be transferred during the season. An appropriate recipient mare will be synchronized to receive the embryo.

It is important for each owner/lessee to understand the regulations of their breed registry regarding registration any resulting foals from vitrified embryos, and any effect of transferring an embryo in a year other than that of the recorded breeding year.

Embryos can be stored at the ERL for $25 per month (up to four embryos). We can also ship embryos to a preferred storage facility of your choice. Additionally fees apply.

ERL Giving Fund
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​3101 Rampart Road
Fort Collins, Colorado 80523-1693

​(970) 491-8626

​(970) 491-7005