Stichocyte

Abstract: The cuticular lining of the lumen of the esophagus of Trichinella spiralis, although continuous with the external cuticle, is not similar to it in structure. Cuticle-lined ducts run from the lumen of the esophagus to systems of canaliculi in the stichocytes, one duct per stichocyte. Cell walls are present in the esophagus; in the infective juvenile and adult 3 cells are present in some regions of the esophagus. A cellular muscular sheath completely or partly surrounds the bulbous and stichosome regions of the esophagus. The ducts from the stichocytes to the esophagus pass through a gap in this cellular sheath. In a previous paper (Bruce, 1966), the structure of the intestine and hindgut of the infective stage of Trichinella spiralis was presented. This paper completes the study of the alimentary tract of this nematode. Chitwood (1930) first recognized that the esophagus of T. spiralis, and of the Trichuroidea as a group, was similar to the esophagus of other nematodes in that it had a triradiate cuticle-lined lumen and associated radial muscles. Hitherto the esophagus of the Trichuroidea had been regarded as a long thin duct penetrating between the glandular cells of the stichosome (Miiller, 1929). Miiller, in a study of Trichuris, concluded that the stichosome and bacillary cells were linked in absorptive metabolic activity, principally because the esophagus was supposed not to have any mechanical function. Chitwood (1935) and Chitwood and Chitwood (1937) described ducts leading from the stichocytes into the esophagus only in Trichuris and not in Trichinella spiralis. Richels (1955) detected similar ducts in a light microscope study of T. spiralis. Beckett and Boothroyd (1961), in a preliminary electron microscope study of T. spiralis, showed the lumen of the esophagus to be triradiate and lined with cuticle. They noted the presence of a "protoplasmic sheath" surrounding the esophagus but did not detect any ducts leading from the stichocytes to the lumen of the esophagus. Received for publication 19 August 1969. * Present address: Department of Zoology, University of Glasgow, Glasgow, W.2., Scotland. MATERIALS AND METHODS The methods of obtaining infective juveniles and of fixation, embedding, sectioning, and viewing were as given in a previous paper (Bruce, 1966). Adult worms were obtained by slitting the gut along its length and placing the opened gut in Tyrode's solution at 37 C for I hr. The worms were collected on a 200-mesh sieve, fixed, and processed as described for the infective juveniles (Bruce, 1966).

Abstract: The ultrastructure of muscle larvae of Trichinella pseudospiralis was studied by electron microscopy. The overall structure of muscle larvae of T. pseudospiralis resembled that of T. spiralis except for the stichocyte granules. T. pseudospiralis had at least 3 kinds of stichocyte granules distinguishable from each other by their shape, size and inclusions. The granules had some resemblance to alpha granules or beta granules of T. spiralis, but no resemblance to gamma granules. In favour of these morphological differences and similarities among T. spiralis and T. pseudospiralis, excretory and secretory (E-S) products (originating from stichocyte granules) of the 2 species differed to some degree. In an analysis by 2-dimensional electrophoresis, some peptide spots migrating at 45 kDa were shared by the 2 species but the other spots were unique to each of the 2 species. Messenger RNA encoding the 43 kDa glycoprotein of stichocyte granules was detected in the muscle larvae of both species but mRNA encoding the 53 kDa glycoprotein was detected only in muscle larvae of T. spiralis.

Abstract: This work investigated the location on the parasite ofTrichinella antigens recognized by the mouse immune system and the question as to which of them bear the epitope phosphorylcholine (PC). Wheatley's trichrome stain (initially developed for faecal smears) proved to be excellent for visualization ofTrichinella structures, enabling four types of stichocyte to be distinguished. By applying this stain on infected muscle sections after immunocytochemistry using (a) anti-PC BH8 monoclonal antibodies, (b) serum from mice that had been infected twice in the presence of 0.05% thiabendazole (to prevent reproduction by adult females) and then bled on day 7 post-reinfection, (c) serum from infected mice that were bled on day 14 postinfection, or (d) serum from infected mice that were bled on day 42 postinfection, we found (1) that PC is an abundant structural epitope on the hypodermis/muscle, genital primordium and intestinal tract but is absent from the cuticle and stichosome; (2) that the principle secretory cells of adult worms are delta- and beta-stichocytes, whereas those of migrating and encysted L1 larvae are alpha-stichocytes; and (3) thatTrichinella antigens recognized in the encysted phase of the parasite's life cycle are present in parasitized myofibres in the sarcoplasmic matrix and in the nucleoplasm of hypertrophic nuclei. The significance of these findings is discussed.

Abstract: Monoclonal antibodies (mAb) recognizing epitopes on the 48K (beta stichocyte specific) and the 50/55K antigen (alpha stichocyte specific) were used as first ligands for immunocytolocalization on de-paraffinized sections of infected gut tissue of non-immune and immune CFW strain mice. The enteral phase was studied at 6, 14, 23, 30 hr and 7 days after initiation of infection via the oral route, times corresponding in worm development to the first (L,), second (L2), and third (L3) stage larva and adult. No change in the intensity of the immune reaction with either mAb was noted in parasites developing within immune or non-immune mice for any of the time-points studied. The 48K and the 50/55K antigens were present within the stichocytes at 6 hr. Enterocytes adjacent to some worms also stained positive for both epitopes at this time. Throughout worm development, the amountil almost none was left at 30 hr. At day 7, the 48K antigen was present within a few stichocyte cells, the canalicular tree, and within the lumen of the midgut. The 50/55K antigen at this time point was localized within only a few stichocyte granules and on the lining of the worm's gut. Embryo stages did not possess either the 48K or 50/55K epitopes. A marked increase in cells bearing IgG in the lamina propria was noted in immune mice when compared with their non- immune counterparts.