A Programmed Cell Death Process Which Begins When a Cell Receives an Internal (e.g. DNA Damage) or External Signal (e.g. an Extracellular Death Ligand) and Proceeds Through a Series of Biochemical Events (signaling Pathway Phase) Which Trigger an Execution Phase. the Execution Phase Is the Last Step of an Apoptotic Process and Is Typically Characterized by Rounding Up of the Cell Retraction of Pseudopodes Reduction of Cellular Volume (pyknosis) Chromatin Condensation Nuclear Fragmentation (karyorrhexis) Plasma Membrane Blebbing and Fragmentation of the Cell Into Apoptotic Bodies. When the Execution Phase Is Completed the Cell Has Died.
The Space External to the Outermost Structure of a Cell. For Cells Without External Protective or External Encapsulating Structures This Refers to Space Outside of the Plasma Membrane. This Term Covers the Host Cell Environment Outside an Intracellular Parasite.