Mouse uterine gene expressions during peri-implantation period

The mouse uterine gene expressions during peri-implantation period at pregnancy day 4 and 6 was investigated by Visium spatial transcriptome. 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. On day 4, one uterine horn was flushed with saline to confirm the presence of blastocysts. 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 40 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.