SFRP5 and adenomyosis: Multiplex Immunohistochemistry (mIHC) labeling E‐cadherin (protein of ECAD, an epithelial marker), sFRP‐5 (protein of SFRP5), and IHH confirmed the distribution of SFRP5+ECAD+ cells in the basal layer of endometrium, which is consistent with the spatial transcriptomics data (Figure S4E, Supporting Information), and the higher expression level of IHH at the invaginating site of adenomyosis (Figure 2L), suggesting that SFRP5+ epithelial cells are the key players in SFRP5+ epithelial ecotypes.