These pigs were made by zygote injection of the CRISPR CAS-9 system with guides targeting both exon 1 and exon 2 of the GDF9 gene, in an effort to elucidate the function of GDF9 in pigs. Resulting pigs were knockouts for the GDF9 gene. Mature gilts never demonstrated standing estrus and had a severely underdeveloped reproductive tract with large ovarian cysts. Further examination revealed that the follicles from the GDF9 −/− gilt did not progress past preantral stages.
- Chen PR, Uh K, Monarch K, Spate LD, Reese ED, Prather RS, Lee K. Inactivation of growth differentiation factor 9 blocks folliculogenesis in pigs†. Biol Reprod. 2023 Apr 11;108(4):611-618. doi: 10.1093/biolre/ioad005. PMID: 36648449; PMCID: PMC10106843.