Glandular tissue is tissue that is designed to secrete something. It is one of the major forms of epithelial tissue, which is the tissue that lines and covers most of the body, from the skin to the inside of the stomach.There are several different kinds, differentiated by how they function.t is one of the major forms of epithelial tissue, which is the tissue that lines and covers most of the body, from the skin to the inside of the stomach. There are several different kinds, differentiated by how they function.