Placental senescence.
As the nature of any intrinsic biologic aging process or even of its existence independent of disease is unknown, it is not possible to state whether or not the placenta gets old. As term approaches, the placenta accumulates a variety of lesions which seem pathological. In most cases, however, it is not certain that they represent intrinsic disease in the sense that older people tend to develop cancer or atherosclerosis. Several placental functions decrease near term, but it is not possible to attribute these to aging. In fact, some may represent adaptive additional maturation. A variety of laboratory phenomena seen in aging cells may be detected in the placenta but again, their significance is uncertain. In short, the placenta looks and acts as if it grows old. That is clinically important and probably all the clinician needs to know, but whether or not it truly grows old remains a mystery, an important point for the biologist. For if the placenta truly ages, then the embryo and its placenta represent genetically identical tissues which age at different rates. Such a model might give us much more specific information about our limits than a currently popular reference, the 90th Psalm.
D002470:Cell Survival; D005260:Female; D006801:Humans; D008062:Lipofuscin / Q000032:analysis; D010920:Placenta / Q000098:blood supply / Q000502:physiology*; D011247:Pregnancy; D013927:Thrombosis / Q000209:etiology
D008062:Lipofuscin