"To remove the tissue" means to take out or extract a part of the body that is made up of cells, such as muscle, skin, or organs, usually during a medical procedure or surgery. Full definition
It involves removing some tissue from the dog's vocal cords. (dog-health-guide.org)
Cell culture studies involve removing tissue (or even individual cells) from a plant or animal and growing them in a laboratory environment. (science.howstuffworks.com)
Right now such cancers are usually confirmed by way of a biopsy — a doctor literally removes tissue and sends it to a lab for analysis, which can take days. (canadianbusiness.com)