Periodicity in the Cytoplasm of Freeze-Cleaved Sheep Erythrocytes

Sheep red blood cells have been freeze-cleaved and the exposed fracture faces have been replicated with carbon, shadowed at a 45° angle with carbon-platinum, and examined in the electron microscope. The cytoplasm appears to be filled with tightly packed particles, the replicas of which measure approximately 120A° in diameter. In large areas, these particles occasionally form extended linear configurations which may be straight or curved. Typically, large numbers of these lines are parallel to one another. It is suggested that the lines in these replicas may represent areas of molecular packing within the cytoplasm of sheep erythrocytes. The possibility that the individual particles may represent a contaminant adsorbed onto the cold freshly cleaved surface prior to replication or that the orderly pattern seen in replicas may be an artifact introduced during glycerination, freezing, or cleaving cannot be entirely eliminated by this data. The authors thank Mrs. Marilyn Schaefer for typing the manuscript and Miss Joyce Jakobsen for preparing the illustrations.