several preparation methods i.e. , freeze-drying and plastic-embedding , freeze-substitution ( 2 days ) and freeze-drying of ultrathin cryosections have been applied to examine the retention of sodium , magnesium , phosphorus , sulfur , ( chlorine ) , potassium and calcium in subcellular compartments ( basal cytoplasm , apical cytoplasm , mitochondria and zymogen granules ) .
C0010834
cytoplasm
C0026237
mitochondria