Final answer:
The T-cell development experiment and vertebrate limb development are examples of how programmed cell death (apoptosis) is cell type specific, highlighting the importance of apoptosis in maintaining proper function and development by selectively targeting certain cells for destruction.
Step-by-step explanation:
The experiment that demonstrates that programmed cell death (apoptosis) is cell type specific refers to various studies conducted in the field of developmental biology and immunology. For example, during T-cell development in the immune system, there is a process where immature T-cells are screened to ensure they don't recognize self proteins. If they do, apoptosis is initiated to prevent autoimmune diseases. This shows that apoptosis is not just a general process but one that can be highly specific to cell type, ensuring proper development and function of the organism.
Another example is the use of external signals to control digital separation in vertebrate limb development. Web-like tissue between developing digits undergoes apoptosis through cell signaling, allowing for the formation of separated fingers and toes. This specificity in apoptosis is crucial for normal anatomical development, again highlighting that apoptosis is induced in a cell type-specific manner.