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.</p
