Irreversible Cellular Changes in Old Mice

CELLULAR changes accompanying ageing are known to occur in a number of organs, for example, liver 1 , bile ducts 2 , pancreas 3 , thyroid 4 and prostate 5 , and may be due to an intrinsic change in the tissue cells or to humoral changes in the host. Most of this work, however, is based on histological investigations of fixed material and little is known about the biological potential of these tissues. In a preliminary investigation 5 the response to hormones of prostatic tissue from young (1.5 months), adult (4–5 months) and old (24 months) mice was investigated in organ cultures and differences in reaction were described. The prostates of the old mice also showed a general epithelial atrophy, but with areas of giant cells and presumed hyperdiploid cells with large irregular nuclei. When these tissues were maintained in vitro on a medium containing normal adult human serum some of these changes regressed, but the cultures were maintained for a relatively short time (21 days). To investigate the effects of the humoral environment on tissues of different ages for longer periods, a series of experiments were carried out by grafting old and young prostatic tissue into hosts of different ages. These animals can be described as age chimeras 6 .