Hif2a–Lox mediated collagen remodelling is crucial for embryo invasion

The mouse uterine gene expressions on pregnancy day 6 were investigated by Visium spatial transcriptome. Contributions of Hif2a-Lox axis was examined by comparing uterine-specific KO mice of Hif2a or Lox with their littermate control. Overall design: The day when the vaginal plug was detected was considered day 1 of pregnancy. Pregnant mice were euthanized by cervical dislocation on designated days of pregnancy for the evaluation of pregnancy phenotypes and sample collection. Embryo attachment sites were observed as blue bands soon after intravenous injection of 1% solution of Chicago blue dye (Sigma-Aldrich) in saline on day6. Collected tissues were snap-frozen. Frozen sections (10 µm) were mounted on gene expression slides and sent to KOTAI Biotechnologies for subsequent procedures. After reaction with Proteinase K for 30 min, the sections were hybridized with spatial tags on the slides and reverse-transcribed in situ. The synthesized cDNAs were subjected to RNA-sequencing using DNBseq (MGI), producing 300 million reads/sample.