In situ fixation of cultured mouse peritoneal exudate cells: comparison of fixation methods.

Mouse peritoneal exudate cells grown in vitro on plastic petri dishes were fixed in situ with both glutaraldehyde and osmium tetroxide by a variety of contemporary methods. The goal of the investigation was to determine which method resulted in the best ultrastructural preservation. The parameters being tested included: (a) the method of fixation, i.e. either sequential or simultaneous; (b) the buffer vehicle for fixation, i.e. cocodylate, Mellonig's phosphate, Sorenson's phosphate, or s-collidine; and (c) the temperature of fixation. Results presented indicate that simultaneous fixation is far superior to sequential methods. Samples fixed sequentially at 4 degrees C consistently had better morphological preservation than samples fixed under similar conditions at 23 degrees C. With the exception of s-collidine, which was totally unacceptable for in vitro in situ fixation on plastic, comparable results were noted with different buffer vehicles.