Ultrastructure of the daughter sporocyst and developing cercaria of Schistosoma japonicum in experimentally infected snails, Oncomelania hupensis hupensis

Ultrastructure of daughter sporocysts and cercariae of Schistosoma japonicum were studied 2 and 4 months after infection of Oncomelania hupensis hupensis. The body walls of daughter sporocysts are similar at all infectious stages. They consist of an external syncytial tegument on a basement membrane, and an internal cellular subtegument surrounding a body cavity containing developing cercariae. The cercariae embryos develop 2 months after infection from germinal balls in the brood chamber of the daughter sporocyst. They are at first enveloped by a primitive epithelium rising from the daughter sporocyst. Four months after infection, the cercariae were almost fully developed and the primitive epithelium had degenerated. The body wall of the cercaria consists of a thin tegument covered by a surface coat of fibrous material and connected to the subtegumental cells by cytoplasmic processes. The matrix of the tegument contains numerous dense bodies, vacuoles, and spines. Two types of sensory structures - uniciliated and multiciliated - are found at the anterior tip of the cercaria. There are five pairs of penetration gland cells of two distinct types differentiated by the morphology of secretory granules. Flame cells are found in both daughter sporocysts and in cercariae. The cilia of the flame cells are characterized by the typical 9 and 2 cilium pattern.

Microtopography of the surface of adult Schistosoma japonicum-like (Malaysian) as observed by scanning electron microscopy

The surface of adult Schistosoma japonicum-like (Malaysian) was studied by scanning electron microscopy. The basic pattern of surface microtopography is similar to other strains of S. japonicum as previously reported. However, among male member there are some unique differences in the types, number and distribution of surface papillae and morphology of ridges. Three kinds of papillae were observed: (1) the large fungiform papillae (3.5-4 micron in diameter, most without cilia) are more numerous than in other strains of S. japonicum, they concentrate on the lateral aspect of the anterior and middle parts close to the edge of the gynecophoral canal, and on the dorso-lateral aspect of the posterior part towards the tail tip; (2) the small hemispherical papillae (1.5-2 micron in diameter, all bearing cilia) are especially numerous in the suckers, the gynecophoral canal and parts of the tegument around the suckers and close to the tail tip; on the rest of the surface they are evenly distributed; (3) the cratered papillae (3-4 micron in diameter, about half having cilia) are more numerous than on other strains, they concentrate on the lateral aspect of the middle part and on the edges of the gynecophoral canal. The surface ridges (about 0.2-0.3 micron in width) are tall, highly branching and perforated; they are most developed in the middle part. Spines were observed only in the suckers and the gynecophoral canals. In contrast to the male, the female has numerous spines on all parts of the surface except the most anterior, where a large number of long cilia were observed. All three kinds of papillae were present; fungiform papillae are more numerous than in females of other strains; they concentrate on the latero-dorsal aspect of middle and posterior parts, and around the excretory pore. Ridges are much less developed than in the male and are prominent only in the middle part.

Morphological alterations of Schistosoma japonicum associated with the administration of amoscanate

Morphological alterations of Schistosoma japonicum induced by the administration of a curative dose (20 mg/kg) of the schistosomicide, amoscanate (4-isothiocyanate-4'-nitrodiphenylamine, CGP4540), were studied. Worms from amoscanate-treated ddY mice exhibited remarkable changes on the surface of male and female worms, as well as in the vitelline cells of females. Various types of lesions, such as swelling and ballooning of the tegument, constriction of folds and channels, disruption of sensory receptors and exfoliation of surface layers, were prominent in many areas of the worm body. These alterations were variable in different worms recovered from the same host. The extent of the lesions was not dependent on the period of recovery after treatment.

Schistosoma japonicum: ultrastructural changes in the tegument during cercaria-schistosomulum transformation

The tegumental changes of Schistosoma japonicum cercaria were initiated when introduced into NCTC 109 containing antibiotics for axenizing. In some regions the tegument was covered with a penta- or heptalaminate membrane, and the surface coat changed into an electron-dense, amorphous material. Large vacuoles limited by a multilaminate membrane were evident in the tegumental cytoplasm, and some appeared to join or open to the tegument. After 4 h incubation in NCTC 109 containing 50% fresh rabbit serum, the outer tegumental membrane of schistosomulum became heptalaminate. The amorphous material was still present on the surface of the tegument. Within 72 h the tegument was covered with a heptalaminate membrane over a greater part of the body, and the amorphous material was very reduced. Large vacuoles in the tegument disappeared and tegumental folds developed in some regions. No amorphous material existed on the surface of 10-day schistosomulum and the outer membrane of the tegument was heptalaminate in almost all regions of the body.

Parasite-parasite interaction of Salmonella typhimurium and Schistosoma

The parasite-parasite interaction of Salmonella and Schistosoma was studied. Salmonella typhimurium LT2 was found to associate in vitro with three human species of Schistosoma: Schistosoma mansoni, Schistosoma haematobium, and Schistosoma japonicum. Genetic mutants of S. typhimurium were allowed to interact with ligatured and unligatured worms of S. mansoni in vitro. These studies were undertaken to elucidate the mechanism(s) of the parasite-parasite interaction of Salmonella on the surface of Schistosoma. The ga/E and fla mutants showed 100% association with male schistosomes, but a reduced interaction with female worms. The rough A and pili mutants showed a significant reduction in the ability to associate with both male and female S. mansoni. Observations with the scanning electron microscope revealed that pili function in adhesion of Salmonella to the surface tegument of S. mansoni and S. haematobium. The association of Salmonella and Schistosoma may contribute to persistence of salmonella infection.

Schistosoma japonicum-like ova in liver and rectal biopsies of three cases in Sabah, Malaysia

Three cases of schistosomiasis in 2 Filipinos and one Chinese in Sabah are reported. Diagnosis was based on incidental histological findings of Schistosoma japonicum-like ova in the liver and rectal biopsies. As these 3 patients are immigrants to Sabah, it is assumed that they are imported cases, and that Sabah has been free of the disease from 1970 to 1977.