Apologies for the pause—to answer clearly: the process you’re referring to is most commonly apoptosis, a regulated form of cell death often described as "programmed cell death" (Type I). Here are the key cell types and contexts in which apoptosis typically occurs or is relevant:

• Normal development and tissue homeostasis
  • Immune system: lymphocytes undergoing negative selection and clonal contraction after immune responses.
  • Developmental sculpting: pruning of interdigital tissue, neuronal pruning, and organ shaping.
• Epithelial and endothelial cells
  • Cells that detect DNA damage, extreme stress, or oncogenic mutations may activate apoptosis to prevent malignant transformation.
  • Epithelial cells can undergo apoptosis during tissue remodeling or in response to loss of extracellular matrix attachment (anoikis).
• Hematopoietic cells
  • B and T lymphocytes during maturation and after antigen clearance.
  • Erythrocyte precursors during erythropoiesis in coordination with macrophage clearance.
• Neurons and glia
  • During development, excess neurons are removed by apoptosis; in disease, neurons may die by apoptosis in response to stress.
• Other somatic cells under stress
  • Cells with irreparable DNA damage, severe oxidative stress, or mitochondrial dysfunction often engage apoptotic pathways to safeguard organismal integrity.

How to identify apoptosis in a cell

• Morphological hallmarks: cell shrinkage, chromatin condensation (pyknosis), nuclear fragmentation (karyorrhexis), formation of membrane-bound apoptotic bodies, and eventual phagocytic clearance.
• Biochemical hallmarks: activation of caspases (executioner caspases like CASP3), mitochondrial outer membrane permeabilization (MOMP) in intrinsic pathways, exposure of phosphatidylserine on the cell surface, and DNA laddering on gels.
• Regulatory pathways: intrinsic (mitochondrial) pathway driven by cellular stress and Bcl-2 family balance; extrinsic (death receptor) pathway triggered by external ligands binding death receptors.

If you can share more about the context (e.g., organism, tissue type, developmental stage, or whether you’re asking about which cells are capable of undergoing apoptosis in a particular system), it will be possible to tailor the details more precisely.