在自然界里,每一种动、植物都有一定的生命期。比如树叶临秋会凋落,蛇到一定时候会蜕掉一层皮。科学家们研究发现,生物体的细胞死亡亦称细胞凋亡,是细胞本身的一种生理性、主动性的“自杀”行为,而绝非由外在因素所致。细胞的死亡是有规律的,而且似乎是按编排好的程序进行的,即 In nature, every animal and plant has a certain period of life. For example, when the leaves fall in the autumn, the snake will pick up a layer of skin at a certain time. Scientists have found that cell death in organisms, also known as apoptosis, is a physiological, active “suicide” behavior of the cell itself, and is by no means caused by external factors. The death of cells is regular, and it seems to be carried out according to a well-planned procedure.