bta-mir-133b: bta-mir-133b is a microRNA (miRNA) that was identified as one of the six miRNAs up-regulated in the oviductal epithelial cells (OECs) of non-pregnant cows, with no up-regulation observed in the OECs of pregnant cows [PMC7969882]. This miRNA, along with others, is predicted to regulate 37 biological pathways in OECs from non-pregnant cows when compared to pregnant ones [PMC7969882]. Despite being up-regulated in non-pregnant cows, bta-mir-133b was previously detected in bovine OECs under varying levels of estrogen (E2) and progesterone (P4), but without significant differences in expression levels when an embryo was not present [PMC7969882]. bta-mir-133b is also listed among the top 20 most abundant miRNAs across all developmental stages [PMC7073773], and its differential expression pattern has been confirmed by stem-loop RT-qPCR, reinforcing its significance as revealed by RNA-Seq [PMC4840452]. Additionally, bta-mir-133b expression was found to be upregulated in an infected compartment compared to a control group, indicating its potential involvement in response to infection [PMC4840452].