Freeze Fracture of Membranes at the Interface between Vegetative and Generative Cells in Amaryllis Pollen

Abstract

The interface between generative and vegetative cells in Amaryllis pollen consisted of the two parallel plasma membranes of these cells. The paired plasma membranes were highly convoluted with broad lobes bulging into the vegetative cells and narrow indentations projecting into the generative cells. In thin sections, rows of knobbed projections were aligned on the inner surface of the vegetative cell plasma membrane. When these membranes were freeze-fractured, the fracture faces of the vegetative cell plasma membrane showed two distinct domains: a particulate fracture face in the lobes and oblique parallel ridges on the indentations. These two domains may correlate with separate functions. The lobes with projections appeared to be attached to the vegetative cell cytoskeleton and may be involved in movement of the generative cell through the pollen tube. The indentations may function to hold the generative cell in place within its cavity in the vegetative cell. These membrane specializations have been obse...