title: Freeze fracture study of the schizonts and merozoites of Leucocytozoon caulleryi.
abstract: The fine structure of the schizonts and merozoites of Leucocytozoon caulleryi was studied by the freeze fracture technique. Young schizonts were spherical, surrounded by a thick fibrous capsule and possessed numerous nuclei. The nucleus was surrounded by the outer and inner nuclear membrane. A number of nuclear pores were evident in the nuclear membranes. Advanced schizonts were characterized by the formation of cytomeres. Each cytomere was surrounded by a membrane. Several nuclei lay along the periphery of the cytomere. The protoplasmic face (P-face) of the membrane of the cytomere contained numerous intramembranous particles (IMP). The exoerythrocytic merozoites were surrounded by a two-layered pellicle consisting of the outer and inner membrane. During freeze fracturing, each of the two membranes could split along its hydrophobic interior to yield a total of four fracture faces. The P-faces of the outer and inner membranes were closely covered with evenly distributed IMP. The external faces (E-face) of these membranes had less IMP than the P-faces. The membrane architecture of the erythrocytic merozoites was similar to that of the exoerythrocytic merozoites. The erythrocytic merozoite was enveloped by an additional membrane probably derived from the plasma membrane of host cell.
mesh_terms: D000818:Animals; D016782:Apicomplexa / Q000648:ultrastructure*; D002462:Cell Membrane / Q000648:ultrastructure; D002645:Chickens; D005614:Freeze Fracturing; D008854:Microscopy, Electron; D009685:Nuclear Envelope / Q000648:ultrastructure