Morris G M, Hamlet R, Hopewell J W
CRC Normal Tissue Radiobiology Research Group, Research Institute (University of Oxford). Churchill Hospital, U.K.
Cell Tissue Kinet. 1989 May;22(3):213-22. doi: 10.1111/j.1365-2184.1989.tb00207.x.
The skin from rats of differing age was used to quantify variations in the cell kinetics of the epidermis and the follicular epithelium of different body sites. Four parameters were assessed, namely the basal cell density (BCD), the labelling index (LI), the duration of DNA synthesis (ts) and the basal cell turnover time (tT). The BCDs of the epidermis of the dorsum and the upper surface of the foot were similar in rats of 7, 14 and 52 weeks of age, but there was an indication of a progressive decline with increasing age in the BCD of the epidermis of the ear and tail. There were no age-related changes in the length of ts in any of the four body regions. The rate of cell proliferation, as indicated by the values of the LI and tT, was relatively rapid in the epidermis of the dorsum, foot and tail of rats aged 7 weeks (LI greater than 12%; tT less than 80 h). In rats aged 14 weeks this rate of proliferation was maintained in the epidermis of the dorsum. However, in the foot and tail the rate of cell proliferation was decreased (LI less than 10%; tT greater than 85 h). A fall in the rate of proliferation of the epidermis of the dorsum was only seen in 52-week-old animals. In these animals the rates of proliferation in the foot and tail were similar to those at the age of 14 weeks. In the epidermis of the ear there was no appreciable change in the rate of cell proliferation with age. The values of the cell kinetic parameters varied in the different body sites. For example, in 52-week-old animals values for tT were relatively short in the epidermis of the tail and foot and appreciably longer in the epidermis of the dorsum and ear. Considered overall, values for the cell kinetic parameters of the epidermis were comparable with those for the follicular epithelium. The only major differences between the epidermis and the follicular epithelium were in the upper surface of the foot at 7 weeks of age, and in the tail at 7 and 14 weeks of age, where the LI was higher and the tT shorter in the epidermis than in the follicular epithelium. The relevance of the observed age- and body-site-related variations in the cell kinetics of the epidermis are discussed in relation to previously described differential changes in the radiosensitivity of the skin in this strain of rat.
使用不同年龄大鼠的皮肤来量化不同身体部位表皮和毛囊上皮细胞动力学的变化。评估了四个参数，即基底细胞密度（BCD）、标记指数（LI）、DNA合成持续时间（ts）和基底细胞周转时间（tT）。7周、14周和52周龄大鼠背部和足背表皮的BCD相似，但耳部和尾部表皮的BCD有随年龄增长而逐渐下降的趋势。四个身体区域中任何一个区域的ts长度均无年龄相关变化。如LI和tT值所示，7周龄大鼠背部、足部和尾部表皮的细胞增殖速率相对较快（LI大于12%；tT小于80小时）。14周龄大鼠背部表皮的这种增殖速率得以维持。然而，足部和尾部的细胞增殖速率降低（LI小于10%；tT大于85小时）。仅在52周龄动物中观察到背部表皮增殖速率下降。在这些动物中，足部和尾部的增殖速率与14周龄时相似。耳部表皮的细胞增殖速率随年龄没有明显变化。细胞动力学参数值在不同身体部位有所不同。例如，在52周龄动物中，尾部和足部表皮的tT值相对较短，而背部和耳部表皮的tT值明显较长。总体而言，表皮细胞动力学参数值与毛囊上皮的相当。表皮和毛囊上皮之间唯一的主要差异在于7周龄时的足背，以及7周和14周龄时的尾部，此时表皮的LI较高，tT较短。结合先前描述的该品系大鼠皮肤放射敏感性的差异变化，讨论了观察到的表皮细胞动力学中与年龄和身体部位相关的变化的相关性。
