In the context of cryopreservation, adding 10% DMSO to 90% FBS refers to mixing two solutions to create a freezing medium for cells or biological samples. Here's a breakdown of the components: • 10% DMSO (Dimethyl sulfoxide): This is a cryoprotectant. During freezing, water in the cells can form ice crystals, which can damage the cell structure. DMSO helps prevent this by reducing the formation of ice crystals and protecting the cell membranes. • 90% FBS (Fetal Bovine Serum): This is a cell culture medium supplement that provides essential nutrients and growth factors for cells. It also contains proteins that can further protect cells during freezing. Therefore, adding 10% DMSO to 90% FBS creates a freezing medium that offers both cryoprotection (DMSO) and cell support (FBS). All the best for your experiment.