The ultrastructure of rapid-frozen, substitution fixed parotid gland acinar cells of the mongolian gerbil (Meriones meridianus).

The ultrastructure of gerbil parotid gland acinar cells studied by rapid freezing in liquid nitrogen and freeze-substituting with OsO4 was similar in general to conventionally prepared tissue, but different in several aspects. Acceptable preservation was limited to about 10 microgram of the surface; the secretory granule membrane was a single dense line, while all others were trilaminar; the dense-cored secretory granule had a rim of low density which was homogeneous; there were many continuous profiles between the Golgi lamellae, vesicles, and vacuoles; and mitochondria were long and arborized.