衰老的机制关于多细胞有机体的衰老问题目前存在着两百多种学说。有些学者认为衰老过程可以分为两个阶段。开始是内分泌系统发生改变,然后神经系统、绍缔组织和血液循环系统才接着发生变化。而机体其他一些衰老性变化则仅是上述各系统机能障碍的结果。由于细胞学说的发展,以及能使组织培养物长期存活,因而又产生了许多新的学说。有的新学说认为衰老是由于在细胞成长过程中原生质和细胞核的比例变得越来越不相称的结果。有的新学说则认为是由于细胞高度分化,失去了分裂的能力,也就是返老还童的能力。还有一种新学说主张衰老是由于原生质逐渐 Mechanisms of aging There are more than two hundred doctrines of aging for multicellular organisms. Some scholars believe that the aging process can be divided into two stages. The beginning is the endocrine system changes, and then the nervous system, Shao connective tissue and the circulatory system only then change. Some other aging changes in the body are only the result of the above system dysfunction. Due to the development of cytology and the long-term viability of tissue culture, many new theories have emerged. Some new doctrine argues that aging is the result of an increasingly disproportionate proportion of protoplasm and nucleus during cell growth. Some new doctrine is that because of the highly differentiated cells, the ability to lose the division, that is, the ability to rejuvenate. There is also a new doctrine advocating aging is due to gradual protoplasm