[The ultrastructure of leptospires after freeze-etching]

The ultrastructure of three strains of leptospires, i.e. L. interrogans serovar Lai strain 017, L. biflexa serovar patoc strain Patoc I and L. illini strain 3055, were studied with the technique of freeze-etching replica. The results showed that (1) the ultrastructure of leptospires after freeze-etching are similar to that observed by means of negative staining and ultrasectioning. There are no dramatic differences among strains of leptospires studied. (2) Globular particles exposed on the resulting two inner membrane faces are asymmetrically distributed. Large areas on EF face studied with numerous globular particles, whereas the PF face had few of them. The density of globular particles varies in different parts of leptospires, from 776/microns2 to 2303/microns2. The globular particles, 14.25 +/- 2.25 nm in diameter, represent membrane proteins in outer envelope of leptospires. (3) Axial filament, 20 nm in diameter, were seen closely surrounded by a 7 nm sheath-like structure. (4) There are subcellular structures in cytoplasm of leptospires. They appear to be ribosomes, chromatins and inclusions.