TEM analysis of membranous structures in parasitized RBCs.

A. Section through an RBC containing an early trophozoite (approximately 15–18 h post-invasion) showing a number of Maurer’s cleft-like

structures (arrows), some of which are centrally located. Bar is 500 nm.

B. Section through part of an RBC containing a more mature parasite (approximately 30–35 h post-invasion) with knobs (K) at the RBC surface.

The Maurer’s clefts (M) run parallel to the surface. Note the electron-lucent lumen and electron-dense membrane of the clefts compared with the

membranes of the PV and TVN (arrows). Bar is 200 nm.

C. Detail of the periphery of a trophozoite showing the extension of the PV to form the TVN (arrows). Bar is 100 nm.

D. Detail of the Maurer’s cleft in which there appears to be electron-dense material on the cytoplasmic side of the unit membrane compared with

the membranes of the TVN (cf. C). Bar is 100 nm.

E. Part of an infected RBC lysed in 50 mg ml-1 digitonin in which a number of spherical structures are associated with Maurer’s clefts (arrows).

K: knob. Bar is 100 nm. Insert: Part of the cytoplasm of a trophozoite at the same magnification as (E) showing a number of coated vesicles associated with an endomembrane system measuring 40–50 nm. Bar is 100 nm.

F. Detail of a Maurer’s cleft from a cell lysed with SLO showing a number of small (20–25 nm) spherical structures associated with the cleft (arrows). Bar is 100 nm.

G. Detail of a Maurer’s cleft from an intact cell in which vesicle-like structures appear to be emanating from the cleft (arrow). Bar is 100 nm. All

illustrations are of A4 parasites except insert (E, G), which are of the K1 line. Kriek N, Tilley L, Horrocks P, Pinches R, Elford BC, Ferguson DJ, Lingelbach K, Newbold CI. Characterization of the pathway for transport of the cytoadherence-mediating protein, PfEMP1, to the host cell surface in malaria parasite-infected erythrocytes. Mol Microbiol. 2003. PMID: 14622410.

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