The indirect immunofluorescent technique has been used to identify antigenic sources in Brugia malayi adults, infective stage larvae and microfilariae in utero employing antisera from human infected with Brugia malayi and Wuchereria bancrofti, cats infected with B.Malayi and B. pahangi and jirds infected with B.malayi and B.pahangi. The tissues exhibiting fluorescence which imply that they are the antigenic sources consist of, in order of fluorescent intensity,the basal laminae lining the body wall and surrounding the internal organs, the apical part of uterine epithelium, the egg shell, the sperm surface

the cuticle, the hypodermis and the hypodermal cords, the somatic muscle cells, the gut epithelium and its luminal conterts, the uterine epithelium and its luminal contents, the testis epithelium and its luminal contents, the developing sperm, and the egg interior. These antigenic tissues in B. malayi give similar staining pattern and fluorescence intensity with all kinds of antisera used, thus, demonstrating common antigens that exist in these three species of lymphatic worms. Inaddition, common antigens also exist in each tissue of various stages of the worms. These antigenic tissues were further studied ultrastructurally by conventional TEM in order to identify which particular parts of the tissues may contribute to the antigens as well as to understand the detailed organization of these tissues. The cuticle overlying the outer plasma membrane of hypodermis comprises basal, median and corticallayers

each of which contains fibrils arranged in different directions. The trilaminate epicuticle covers the outermost layer of the cuticle. The possible antigenic sources from the cuticle and the epicuticle may be collagen-like proteins which are the fibrillar components of the cutide itself, and phosphoryicholine containing molecules and glycoprotein locating in the epicuticle. The hypodermis is a thin strip of th cytoplasmic syncytium lying between the cuticle and the somatic muscle cells and thickens toward the pseudocoelom between the muscle sectors to form four cord, namely two lateral, one dorsal and one ventral bypodcrmal cords. The hypodermis, especially the lateral cord show particularly important and metabolically active parts of the nematode, being responsible mainly for secretion and mainteance of the cuticle. The dorsal and ventral cords participated in the nervous functions because they contain numerous nerve fibers which are related to the muscle through the formation of the interdigitating caps, and equivalent structure to the neuromuscular junctions. The possible antigenic sources from the hypodermis should be the procollagen that may be less concentrated than in the cuitcle. The somatic muscle cells underlying the hypodermis are grouped into four sectors. Each cell consists of subhypodermal myofibrillar part and nonmyofibrillar organelle-bearing part. The myofibrillar part contains thick and thin filaments,with each thick filament surrounded by 10 to 12 thin ones. The muscular processes extend from the nonmyofibrillar part to form interdigitating caps over their respective dorsal and ventral cords. In addition to contractile function, the muscle cells store a large quantity of glycogen in the nonmyofibrillar part that may serve as a reserve energy for the whole worm. Possible antigens from the muscle cells could be the components of the muscle cells themselves, somatic phosphorylcholine, and neurotuansmitters released at the neuromuscular junctions. A thin basal laminae separate the body wall and the pseudocoelom and it is continuous with the intercellular laminae surrounding muscel cells and all hypodermal cords. These laminae appear homogeneous with finely dispersed granularity. Basal laminsae encircle intestine and reproductive tract, separating these organs from the pseudocoelom. The basal lamina of the intestine and male reproductive tract possess more granularity and appears to have distince layers while that of female reproductive tract contains visceral muscle cells embedded in it. These thick basal laminze probably serve as a structure preventing the organs from collapse against the high osmotic pressure within the pseudocoelom and the lumen. Futhermore, all basal laminae act as the barriers for diffusion of nutrient materials, excretory and secretory (ES) substances, that may pass in and out of the internal tissues and the cuticle. These materials together with some structural components of basal laminae themselves may be another sources of antigens. The pseudocoelom, the body cavity of filarial nematodes, is filled with pseudocoelomic fluid which baths all the internal organs. The pseudocoelomic fluid contains dispersed electron dense precipitations which also attach to the surface of the basal laminae of the body wall and internal organs. These eletron dense materials are presumed to be nutrient materials as well ES substances and waste products, all of which are stored simultaneously in the pseudocoelom, and may be another antigenic sources. The intestine is the longest part of the digestive tract that is lined by an epithelium whose cells possess characteristics suggesting that they are actively synthesizing and secreting in addition to acting in absorption of food. The presence of microvilli, numerous ribosomes and secretory granules in the cytoplasm of intestinal cells indicates that these cells have high secretion activities perhaps of many digestive enzymes which may be represented by the moderate electron dense materials in lumen. Another important role of th eintestine is in excretion of waste products from the body as proven in other nematodes in many previous studies. The antigenic sources of the intestine could be composed of ES products in both intestinal epithelium and the lumen. All regions of th efemale reproductive tract, including the seminalreceptacle, the uppermiddle, and lower parts of the uterus, possess similar characteristic epithelium which is a syncytium that show fimbriation at the luminal surface as well as containing abundant organelles which indicate high synthesis and secretion activities. The particles observed in the uterind lumen have the same characteristics and electron density as the contents in the uterine epithelium or this strongly suggests that there are copious secretion of various materials into the lumen. The uterine epithclium secretes materials for the nutrients for the developing microfilariae in the uterine lumen as well as for the formation of the outermost layer of the egg shell. Therefore, the possible antigenic sources of the uterine epithelium could be composed of the uterine secretions and the egg shell. The ultrastructural characters of epithelium lining seminal vesicle and vas deferens also give the impression that they are actively secerting cells. The secreted substances are believed to be spermatozoa nutrients as well as stimulating substances for feritlization. These substances appear as electron dense precipitations lining the surrounding sperm plasma membrane and the epithclial cell surface, hence they may be another antigenic source.