Cell death during embryogenesis

[Geoff Goodhill]

Those following the current thread on cell death may be interested in
a recent experimental investigation of this during development of the
mouse by Blaschke, Staley & Chun (abstract below). The most striking
finding is that at embryonic day 14, 70% of cortical cells are dying.

Geoff Goodhill
The Salk Institute
10010 North Torrey Pines Road
La Jolla, CA  92037
Email: geoff at salk.edu
http: www.cnl.salk.edu/~geoff


      TI: WIDESPREAD PROGRAMMED CELL-DEATH IN PROLIFERATIVE AND 
          POSTMITOTIC REGIONS OF THE FETAL CEREBRAL-CORTEX
      AU: BLASCHKE_AJ, STALEY_K, CHUN_J
      NA: UNIV CALIF SAN DIEGO,SCH MED,DEPT PHARMACOL,NEUROSCI & BIOMED 
          SCI GRAD PROGRAM,9500 GILMAN DR,LA JOLLA,CA,92093
          UNIV CALIF SAN DIEGO,SCH MED,DEPT PHARMACOL,NEUROSCI & BIOMED 
          SCI GRAD PROGRAM,LA JOLLA,CA,92093
          UNIV CALIF SAN DIEGO,SCH MED,DEPT PHARMACOL,BIOL GRAD 
          PROGRAM,LA JOLLA,CA,92093
      JN: DEVELOPMENT, 1996, Vol.122, No.4, pp.1165-1174
      IS: 0950-1991
      AB: A key event in the development of the mammalian cerebral cortex
          is the generation of neuronal populations during embryonic 
          life, Previous studies have revealed many details of cortical 
          neuron development including cell birthdates, migration 
          patterns and lineage relationships, Programmed cell death is a 
          potentially important mechanism that could alter the numbers 
          and types of developing cortical cells during these early 
          embryonic phases, While programmed cell death has been 
          documented in other parts of the embryonic central nervous 
          system, its operation has not been previously reported in the 
          embryonic cortex because of the lack of cell death markers and 
          the difficulty in following the entire population of cortical 
          cells, Here, we have investigated the spatial and temporal 
          distribution of dying cells in the embryonic cortex using an in
          situ end-labelling technique called 'ISEL+' that identifies 
          fragmented nuclear DNA in dying cells with increased 
          sensitivity, The period encompassing murine cerebral cortical 
          neurogenesis was examined, from embryonic days 10 through 18, 
          Dying cells were rare at embryonic day 10, but by embryonic day
          14, 70% of cortical cells were found to be dying, This number 
          declined to 50% by embryonic day 18, and few dying cells were 
          observed in the adult cerebral cortex. Surprisingly, while 
          dying cells were observed throughout the cerebral cortical 
          wall, the majority were found within zones of cell 
          proliferation rather than in regions of postmitotic neurons. 
          These observations suggest that multiple mechanisms may 
          regulate programmed cell death in the developing cortex, 
          Moreover, embryonic cell death could be an important factor 
          enabling the selection of appropriate cortical cells before 
          they complete their differentiation in postnatal life.
      KP: RHESUS-MONKEY, POSTNATAL-DEVELOPMENT, MIGRATION PATTERNS, 
          REGRESSIVE EVENTS, DNA FRAGMENTATION, NERVOUS-SYSTEM, GANGLION-
          CELL, VISUAL-CORTEX, MOUSE, RAT
      WA: PROGRAMMED CELL DEATH, CEREBRAL CORTEX, EMBRYONIC DEVELOPMENT, 
          MOUSE