adjacent frozen samples from the same heart were processed by freeze-substitution ( followed by embedding and thin sectioning ) , freeze-fracture/etch ( followed by platinum/carbon replication ) and frozen sectioning ( followed by freeze-drying ) , respectively , and examined with the electron microscope for fidelity of reproducing the in vivo state of heart muscle geometry , especially that of the narrow intercellular clefts between frog cardiac muscle cells .
C0027061
of heart
C0225828
cardiac muscle cells