Preparing living pollen material for scanning electron microscopy using 2,2-dimethoxypropane (DMP) and critical-point drying.

A simple, quick, and inexpensive method for preparing any type of pollen material is described. Fresh, mature pollen grains without previous chemical fixation are dehydrated in acidified 2, 2-dimethoxypropane (DMP) followed by critical-point drying in CO2. This method helps preserve size, shape and surface details of both fragile pollen grains and pollen grains that are heavily covered with pollenkitt. Handling of already opened anthers and avoiding loss of pollen grains during the preparation steps are also described. With the DMP direct method, many morphologically and functionally important details that may be lost by conventional methods are well preserved without shrinkage, distortion, or dissolution. The DMP direct method is performed with pollen grains and the results are compared with two other frequently used methods, acetolysis and critical-point drying of chemically fixed material.