Final answer:
Cells that are lost from tissues via programmed cell death are those that are no longer necessary or are damaged.
Step-by-step explanation:
When cells in tissues reach the end of their effective lives or are genetically damaged, they undergo programmed cell death, or apoptosis. This is a process where cells are cleared from tissues and replaced by stem cells. The cells that are lost from tissues via programmed cell death are those that are no longer necessary or are damaged in some way.