Pregnancy establishment in cattle without embryonic interferon tau.

Embryonic interferon tau (IFNT) is not essential for pregnancy establishment or full-term gestation in cattle, as evidenced by successful pregnancies without it.

• Why it matters: This challenges the longstanding belief that IFNT is the critical signal for maternal recognition of pregnancy in ruminants, highlighting a significant gap in understanding of reproductive signaling mechanisms.
• What they did: Using CRISPR-Cas9, researchers created bovine embryos lacking all functional copies of the IFNT gene, then transferred these embryos to recipient cows to observe development and pregnancy outcomes.
• The result: Despite the absence of IFNT, the embryos prevented luteolysis, established normal placentation, and resulted in healthy calves, indicating alternative signaling pathways enable pregnancy in cattle.