The ultrastructure of the neuronal growth cone: new insights from subcellular fractionation and rapid freezing studies.
In this review I have discussed the ultrastructure of the growth cone in relation to two aspects of growth cone behaviour; motility and membrane recycling. There are obvious and severe limitations in studying such a dynamic entity as the growth cone with the static images produced by the electron microscope, but these notwithstanding, electron microscopy, as I have tried to show here, has made important contributions in this area. Notable amongst these contributions is the fairly complete catalogue we now have of the organelles within the growth cone and their spatial relations, in particular the cytoskeletal and membrane bounded elements. Among the important questions that remain unanswered are those relating to the source and destiny of plasma membrane components, especially those concerned with recognising extrinsic cues, and the control of the cytoskeleton in relation to neurite extension and growth cone guidance. These questions can be approached using electron microscopy especially the rapid freezing and deep-etching methods used in conjunction with specific probes such as antibodies and we can look forward to progress in these areas in the near future.
Gordon-Weeks
P R
PR
Dept. Anatomy and Human Biology, King's College London (KQC), Strand, U.K.
D000818:Animals; D001369:Axons / Q000378:metabolism / Q000648:ultrastructure*; D002465:Cell Movement; D003599:Cytoskeleton / Q000648:ultrastructure; D003712:Dendrites / Q000378:metabolism / Q000648:ultrastructure*; D005615:Freezing; D007425:Intracellular Membranes / Q000378:metabolism / Q000648:ultrastructure; D008854:Microscopy, Electron / Q000379:methods*; D015388:Organelles / Q000648:ultrastructure; D013347:Subcellular Fractions / Q000648:ultrastructure