Ultrastructural studies on the microfilaria of Brugia malayi

Ultrastructure of microfilaria Brugia malayi was investigated with electron microscope. Microfilariae are covered by a sheath membrane with dense materials on its outer surfaces. The cuticle consists of 3 layers; namely, external cortical, internal cortical and fibrous layer. Beneath these cuticular layers, thin hypodermis is present and the muscle cells are arranged of 4 groups in a crosssection except for the head and tail. A pair of cephalic channel containing several cilial rods opens at the anterior end of the worm. A hook is situated on the anterior edge of one channel orifice, and several spines grow on the opposite side to the hook. Caudal channels paired laterally opening into the both sides of the posterior region differ from cephalic channels by the presence of a single cilial rod. A central canal runs from the buccal cavity to the inner body, and opens into the inner body cell through the filamentous apparatus. The inner body appears to consist of several cells having storage substances and a flat nucleus located on the periphery of the cell. An excretory apparatus, i. e., a cell, is composed of a nucleus and a large vesicle which has many microprojections on the luminal surfaces. The GI cell which occupies the whole width in a cross-section is larger than the R cell. R2-R4 cells appear to be in a close contact with the anal apparatus having many microprojections on the luminal surfaces. These microprojections differ from those of the excretory vesicle in their thickness and length. The characteristic patterns of these organs are compared with other microfilariae.