What is the definition of Reserves Blood Cells?

"Reserves blood cells" is like saying we have a secret stash of superheroes hiding in plain sight in our bloodstream, ready to spring into action at a moment's notice. Just imagine this: "The superhero blood reserve was alerted to the cosmic crisis, but decided to stay in the basement for a marathon instead of saving the world today." Talk about an unsettlingly mundane superhero story!