Apoptotic detection methods--from morphology to gene.

To date, many terms have been given for cell death and forgotten before they became widely accepted. Most researchers studying cell death use some terms for cell death that have survived over centuries and regard apoptosis and programmed cell death (PCD), and necrosis and oncosis as synonymous. The different terminologies used for cell death depending on the preference of researchers sometimes cause confusion in the study of apoptosis. The study of apoptosis was first based on cell morphology using transmission electron microscopy (TEM): chromatin condensation, cellular shrinkage, budding and apoptotic body formation. Recently, marked progress in biochemistry, molecular biology and genetics provided researchers of apoptosis various tools for apoptosis detection, such as the terminal deoxynucleotidyl transferase (TdT)-mediated dUTP-biotin nick end-labeling (TUNEL) method, agarose gel electrophoresis using extracted DNA, staining methods using fluorescence dyes, and flow cytometry. This review focuses on the following topics: history of the study of cell death and its classification, apoptosis-related proteins and their signal pathways, morphological, biochemical and molecular biological methods of apoptosis detection, and the transcriptional regulation of bcl-2 using the real-time Southwestern method and cancer gene therapy. In addition, the merits and demerits of the above-mentioned apoptosis detection methods are discussed.