Embryology Research Today is a free monthly online journal that collates and summarizes the latest research about Embryology, including details on stem cells, reproduction, transplants, cloning.

Cell death in development: shaping the embryo.

Penaloza C, Lin L, Lockshin RA, Zakeri Z

Department of Biology, Queens College and Graduate Center of CUNY, Flushing, NY, 11367, USA, Zahra_Zakeri@qc.edu.

Cell death in animals is normally classified as type I (apoptotic), type II (autophagic) or necrotic. Of the biologically controlled types of death, in most embryos apoptosis is the most common, although in metamorphosis and in cells with massive cytoplasm type II is often seen, and intermediate forms are seen. For vertebrate embryos other than mammals, apoptosis is not seen prior to gastrulation but thereafter is used to sculpt the organs of the embryo, while overproduction of cells with subsequent death of excess cells is a common means of generating high specificity with low information cost. In zebrafish at least, the inability of embryos prior to the maternal-zygotic transition to undergo apoptosis appears to derive from the inability of the cells to resist lysis once apoptosis begins, rather than any inhibition of apoptosis. In mammalian embryos, apoptosis is seen during cavitation. Thereafter, as in other embryos, cell death plays a major role in shaping and sculpting the embryo. In those situations that have been carefully studied, cell death is under tight genetic control (including regulation of gene products whose function in cell death is not yet known, such as cdk5), with activation of apoptosis sometimes regulated by local environmental variables.

Published 11 August 2006 in Histochem Cell Biol, 126(2): 149-58.
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