Ultrastructure of the microfilaria of Brugia pahangi (Buckley and Edeson, 1956) Buckley, 1958

The microfilaria of Brugia pahangi obtained from an experimentally infected dog were observed with the electron microscope. The sheath was composed of small granules and was covered with electron-dense particles on the outer surface and with small granules on the inner surface. The cuticle was composed of an outermost layer, a trilaminate membrane and an inner layer. The hypodermis was composed of four components as in the adult stage (two small ones on the lateral sides, two large ones on the dorsal and ventral sides). The muscle cells comprised a single layer under the hypodermis on the dorsal and ventral sides. On each side, two muscle cells usually appeared in a transverse section. The thick myofilament was surrounded with 8 to 12 thin myofilaments. Dense bodies were present around the cephalic space. In the cells of the nuclei column, the cytoplasm was very narrow, and the electron-dense nucleus close to each other. The cuticular central canal was connected to the buccal cavity and to the inner body. A sponge-like structure was seen at the junctional part of the canal and the inner body. The inner body showed a homogeneous granular appearance. Eight cephalic papillae were observed at the head tip. Two amphids, each having more than eight cilium-like structures, were connected with the nerve elements and open in the head part. Two phasmids, each having one ciliumlike structure, opened in the caudal part. Two types of neurosecretory granules were observed in the nerve ring and the dorsal and ventral longitudinal nerves were clear except in the anterior and the posterior part of the worm. The excretory and the anal vesicles had contacts with thin and thick cytoplasmic processes respectively, and these vesicles opened to the exterior. The nuclei of the G cell and R cells showed similar electron-density. Lamellate structures were present in the muscle and the hypodermis.