摘要：

Fast freezing of biological cells, called cryofixation, arrests physiological processes and makes them accessible to investigation by electron microscopy and electron probe microanalysis. We have used time-controlled cryofixation to study morphological alterations and elemental shifts during fast exocytosis of organelles. Two examples: Exocytosis of trichocysts in Paramecium caudatum and discharge of nematocysts in Hydra attenuata are considered in more detail. Although the mechanisms of both processes are not yet understood, X-ray microanalysis of cryosections from cells frozen after defined time intervals following stimulation provides data on element distribution, which might help to elucidate the underlying biological functions. Finally, possibilities and limitations of time-controlled cryofixation are discussed with respect to diffusion length of ions and freezing time.

展开