Final answer:
Terminally differentiated cells are cells that can only reproduce their own specific cell type when they divide, as they have exited the cell cycle and entered a non-dividing phase called G0.
Step-by-step explanation:
Terminally differentiated cell types can only give rise to more of their own specific cell type when they divide. These specialized cells have exited the cell cycle and entered a phase known as G0, where they perform a specific function for the remainder of their lifespan. For example, red blood cells, which have a half-life of about 60 days, are regularly replaced by reticulocytes produced in bone marrow. Totipotent stem cells give rise to any cell type in the human body during the early days post-fertilization. As differentiation continues, multipotent, oligopotent, and unipotent stem cells emerge, each with progressively restricted potential. Multipotent cells can differentiate into cell types within a given lineage, oligopotent cells are limited to becoming one of a few different cell types, and a unipotent cell is fully specialized and can only reproduce its own type.