Menstruation: Once unspoken but now uncovered, one cell type at a time.

Despite the burden of menstrual disorders, menstruation is intractable for mechanistic studies because few species menstruate. A paper by Nikolakopoulou et al.1 in Cell Stem Cell introduces an in vitro menstrual cycle model based on human endometrial epithelial organoids as a starting point to reveal insights into the menstrual process.