The bag tissue layer is a type of protective layer found in some mammals, including humans. It is a layer of connective tissue that envelops and cushions organs such as the heart, lungs, and kidneys. The layer is composed of collagen and elastin fibers that are arranged in a three-dimensional network, which gives the layer its strength and elasticity. It helps protect the organs from shock, and also helps them to stay in place. Additionally, the bag tissue layer helps to regulate the temperature of the organs, and it also plays a role in controlling the amount of fluid and electrolyte balance in the body.