Genetic regulation of embryo death and senescence

The survival of the preimplantation mammalian embryo depends not only on pr oviding the proper conditions for normal development but also on acquiring the mechanisms by which embryos cope with adversity. The ability of the ear ly conceptus to resist stress as development proceeds may be regulated by d iverse factors such as the attainment of a cell death program and protectiv e mechanisms involving stress-induced genes and/or cell cycle modulators. T his paper reviews the recent research on the genetic regulation of early em bryo cell death and senescence focussing on the bovine species where possib le. The different modes of cell death will be explained, clarifying the con fusing cell death terminology, by advocating the recommendations set forth by the Cell Death Nomenclature Committee to extend to the embryology resear ch field. Specific pro-death and anti-death genes will be discussed with re ference to their expression patterns during early mammalian embryogenesis. (C) 2000 by Elsevier Science Inc.