Quick Summary
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A freemartin is defined as a female that shares placental vascular connections with a male twin during fetal development and is sterile as a result of in utero exposure to masculinizing hormones produced by the male. A connection between the two fetal circulatory systems develops early in gestation (anastomosis) and leads to the exchange of blood between the fetuses. As a result of this shared blood circulation, both offspring acquire some of the other's cells, rendering both XX/XY chimeras. Exposure to male hormones leads to underdevelopment of the female twin's reproductive tract. Consequently the female twin (a freemartin) is infertile.
Not all twins share placental vascular connections, so not all females that are born co-twin to males will be freemartins. Additionally, a freemartin may be externally indistinguishable from a fertile female. This test assists owners and breeders to identify suspected freemartins and verify the freemartin status of a female born co-twin to a male.
Sample Collection
The freemartin test requires a blood sample.
VGL requires 8-10 mL of whole blood in an EDTA purple top for testing
- Label the tube with the animal's name exactly as it appears on the order
- Place the tube in a plastic bag and pack the blood well enough to withstand the rigors of shipping - we cannot test a broken sample
- Please include an ice pack to keep the sample cool while in transit
- We highly recommend sending the sample overnight through FedEx or UPS at the beginning of the week as we do not have staff on the weekend to process samples
For samples mailed through US Mail (includes priority and overnight):
Veterinary Genetics Laboratory
PO Box 1102
Davis, CA 95617-1102
For samples mailed through FedEx/UPS/DHL etc:
Veterinary Genetics Laboratory
University of California Davis
Old Davis Road
Davis, CA 95616
