Evidence of de novo membrane generation in the mechanism of mast cell secretory granule activation.

Evidence which suggests the occurrence of a rapid new membrane assembly has been observed in the secretory granules of the rat peritoneal mast cell during the early stage of granule activation. The rapid insertion of these newly generated vesicles enables the perigranular membrane of the activated granule to enlarge and expand prior to fusion with the plasma membrane and/or with the neighboring granule membranes. If the newly inserted membrane represents "specialized fusogenic membrane patches", then the presence of de novo membrane generation as an integral step in the mechanism of mast cell granule exocytosis would constitute a fail-safe mechanism in histamine release.