日本血吸虫子胞蚴超微结构的研究：产孔的形态学证明

本文用透射电镜观察我国大陆品系日本血吸虫子胞蚴前端、收缩区和扩张区的超微结构。发现子胞蚴前端存在体被凹陷区及括约肌的构造,同时可见神经细胞。这个子胞蚴精细分化区可能具有产孔的生理功能,尾蚴从产孔中逸出是非创伤性逸出功能的一种生理适应。并与曼氏血吸虫子胞蚴产孔的超微结构进行了比较。     

Transplantation of Schistosoma japonicum daughter sporocysts in Oncomelania hupensis

Schistosoma japonicum daughter sporocysts obtained from infected Oncomelania hupensis hupensis were successfully transplanted to parasite-free O. hupensis hupensis. Survival and infection rates of recipient snails were 80% and 75% respectively. Intramolluscan development of transplanted daughter sporocysts in recipient snails appears to proceed in a similar manner as those reported for transplanted S. mansoni and S. haematobium in their respective snail intermediate hosts. Complete colonization of the digestive gland of recipient snails by sporocysts was observed 80 days after transplantation. Cercarial production during a 10-day observation from recipient snails was characterized by periods of high and low and irregular daily emissions. The average daily cercarial production was 150 per snail. Cercariae produced by recipient snails were infective to mice. Of those cercariae exposed to mice, approximately 30% developed to adult schistosomes. These results have definitive utility in the maintenance of S. japonicum in the laboratory.     

The development of the primitive epithelium and true tegument in the cercaria of Schistosoma mansoni.

The formation of the final cercarial tegument of Schistosoma mansoni is preceded by that of a so-called primitive epithelium. The primitive epithelium is derived from the tegument of the daughter sporocyst. The final cercarial tegument is formed from peripherally located somatic cells of the cercarial embryo, which expand and coalesce beneath the primitive epithelium. The primitive epithelium degenerates and disappears. The ultrastructure of both epithelia in the course of the development of the cercaria is described in detail. Possible functions are discussed.     

长尾蚴吸虫幼虫在菲律宾蛤仔的寄生部位及其组织化学的研究

本文报道长尾蚴吸虫幼虫在菲律宾蛤仔的寄生部位及其组织化学的研究,长尾蚴吸虫幼虫主要寄生于哈仔的生殖腺组织中,仅少部分进入生殖腺附近的消化腺,鳃等。受感染严重的蛤仔,其生殖腺的滤泡等组织被虫体占满并被耗尽,长尾蚴吸虫子胞蚴的胞壁及尾蚴的皮导主要含碱性蛋白质和粘蛋白,子胞蚴的胚球,尾蚴的吸盘,生殖原基,单细胞腺体主要ＤＮＡ阳性物质,排泄囊含丰富的碱性蛋白质;尾蚴体的中部含有呈颗粒团的粘蛋白和抗淀粉酶的     

Schistosoma mansoni: topochemical features of cercariae, schistosomula, and adults

The teguments of developing and mature cercariae, recently transformed, and 1-wk-old schistosomula and adult worms were examined for the ultrastructural location of macromolecular carbohydrates and polyelectrolytes. The surface of mature cercariae within sporocysts and cercariae released from the snail is covered by a filamentous coat which reacts with cytochemical reagents for the demonstration of vicinal glycols, but neither the coat nor the surface of the tegument plasmalemma binds cationic colloidal iron at low pH.Upon penetrating mammalian skin, the cercaria sheds its surface coat; the tegument surface of newly transformed schistosomula, older schistosomula and adult worms stains en bloc with acidic colloidal iron, as does the tegument plasmalemma of mature cercariae if the overlying filamentous coat is first removed by physicochemical means. The cercarial coat thus serves to mask anionic groups at the surface of the tegument plasmalemma which become functionally exposed after penetration of the mammalian host. The distribution of colloidal iron binding sites coincides with those for the carbohydrate-complexing phytohemmagglutnin, concanavalin A, which suggests that these membrane-fixed anions are acid mucopolysaccharides, glycoproteins or glycolipids. Carbohydrate-containing material was also localized within membrane-bound vesicles of the tegument matrix and perikarya of developing cercariae and postcercarial schistosomes, suggesting that surface mucosubstances contributing to the tegument glycocalyx of these worms are elaborated, at least in part, by the tegument itself.     

日本血吸虫胞蚴期超微结构的初步观察

本文用扫描与透射电镜观察了我国大陆品系37日和45日龄日本血吸虫母胞蚴及其体内未成熟子胞蚴体被的结构。同时观察了取自螺肝组织的62日龄成熟子胞蚴。初次揭示日本血吸虫胞蚴期体被的超微结构,基本上与曼氏血吸虫胞蚴期相似。日本血吸虫母胞蚴和成熟子胞蚴除体被无体棘外,其他很相似。比较未成熟的子胞蚴与未成熟的尾蚴,揭示外质膜由两层结构构成;随后,外层结构溶化消失,而同时出现微绒毛。构成这样母子二代胞蚴及其体内胚胎既相同又有差别,认为与幼虫寄生部位及生殖生理状态有关。     

腔阔盘吸虫尾蚴及后蚴穿刺腺等腺体的组织化学及其功能的初步研究

本文报道应用组织化学反应方法初步观察了腔阔盘吸虫(Eurytrema coelomaticum)尾蚴及后蚴体中单细胞腺的组织化学成分及其生理功能。尾蚴的5对大单细胞腺主要分泌粘蛋白、酸性粘多糖及微量碱性蛋白质,当子胞蚴被排到外界时,此腺体物质分泌出充满子胞蚴内囊腔并包被着各尾蚴。尾蚴在此腺体分泌物保护下渡过其在外界生存的时间。尾蚴的4对小单细胞腺主要包含中性糖蛋白及结合氨基的蛋白质(可能是含酶物质),此腺体物质可能是在尾蚴进入昆虫宿主(草螽)体内穿钻其胃壁进入血腔时分泌出能溶解胃壁组织帮助尾蚴的穿钻行为。成熟后蚴的穿刺腺对PAS反应呈强阳性,其分泌物可以溶解囊蚴的囊壁,使后蚴迅速脱囊。各幼虫期其他器官组织的组化成分也经观察。     

Differential expression of LacdiNAc,fucosylated LacdiNAc,and Lewis x glycan antigens in intramolluscan stages of Schistosoma mansoni

We report the expression of 3 well-characterized adult Schistosoma mansoni glycan antigens among molluscan stages of the parasite. These antigens are LacdiNAc (LDN; GalNAcbeta1-4GlcNAc-R), fucosylated LacdiNAc (LDNF; GalNAc[Fucal-3]beta1-4GlcNAc-R), and Lewis x (Le(x); Gal[Fucalpha1-3]beta1-4GlcNAc-R). The presence of the glycans was determined by both immunoblot and immunohistological methods using monoclonal antibodies that specifically recognize each glycan epitope. Immunoblot analyses reveal that LDN and LDNF epitopes are expressed on many different glycoproteins, including eggs, mother sporocysts, daughter sporocysts, and cercariae, although LDN expression among daughter sporocysts is greatly reduced. LDN and LDNF epitopes are localized on the tegument and in the intrasporocyst cell masses of both in vitro-derived and in vivo-derived mother sporocysts and in the daughter sporocysts derived on day 16 after infection. Unexpectedly, high levels of LDN and LDNF glycans were detected in the infected, but not in the uninfected, snail hemolymph, suggesting that the infecting larvae secrete LDN and LDNF glycoconjugates into the snail hosts. In contrast, the expression of Le(x) antigen among the molluscan stages is highly restricted. Le(x) is present on a few high-molecular weight glycoproteins in eggs and cercariae but is undetectable in mother and daughter sporocysts. Taken together with our earlier studies on vertebrate stages of S. mansoni, these results show that LDN and LDNF glycans are conserved during schistosome development. The study further extends the evidence that Le(x) is a developmentally regulated antigen in schistosomes.     

Infectivity of a microsporidium of mosquitoes (Nosema algerae) to larval stages of Schistosoma mansoni in Biomphalaria glabrata

Lai P. F. and Canning E. U. 1980. Infectivity of a microsporidium of mosquitoes (Nosema algerae) to larval stages of Schistosoma mansoni in Biomphalaria glabrata. International Journal for Parasitology10: 293–301. Nosema algerae derived from a closed colony of Anopheles stephensi was fed to Biomphalaria glabrata infected with Schistosoma mansoni. Mother and daughter sporocysts became hyperinfected but the snail tissues remained free of the microsporidia except for rare small aggregates of spores. These lay close to the sites occupied by mother or daughter sporocysts and were probably liberated from them. Irrespective of dose, fewer snails contained infected sporocysts when spores were given at 7 days post-miracidial infection than when given at 14 days. These periods corresponded respectively to stages when mother sporocysts only or daughter sporocysts as well were present in the snails. Infection of the sporocysts began in the tegumental cells, spread to the brood chamber and ultimately to the cercariae themselves. Heavily infected sporocysts contained fewer developing embryos. Doses of 10⁶ and 10⁷ spores/snail caused significant depression of cercaria output when given at 14 days but not at 7 days.     

Observations on the host-parasite relations between Echinostoma revolutum and lymnaeid snails.

Echinostoma revolutum from Taiwan was studied in lymneid snails at 29 +/- 0.5 degrees C. Given 3-5 miracidia, 95% of Lymnaea ollula and 40% of Lymnaea swinhoei became positive; the prepatent periods were 18 and 25 days, respectively. The following are based on the observations in Lymnaea ollula: The time required for miracidial penetration was about one hour. The sporocysts developed only in the ventricle of the snail but mother rediae developed in the heart and other organs. Mature daughter rediae were not found in the heart cavity. The sporocysts reached the ventricle within 3 days. Mother rediae were released after 6 days and daughter rediae after 8 days. Given 5 miracidia, 1-3 sporocysts reached the heart and 2-20 mother rediae were found per snail. The number of mature daughter rediae was usually 100-200 although more than a thousand may develop in a snail. The sporocysts and mother rediae attained maximal size 9 days postinfection and started degeneration 13 days postinfection. Daughter rediae were largest at the beginning of cercarial emergence and decreased in size thereafter. Simultaneous production of daughter rediae and cercariae by the mother redia was seen only once in this snail mature cercariae were obtained in 10 days postinfection. The cercariae emerged from a small area of mantle collar near the posterior corner of shell aperture. They were negatively phototactic and positively geotactic. An estimation showed that each snail shed about 350 cercariae a day. The cercariae reached the pericardial cavity of snail in one hour via the renal orifice and metacercariae were seen 4-5 hours after exposure. The infectivity of cercariae at various times after shedding, as expressed by cyst recovery rates, were: 51.6%, O-hr old; 76.1%, 2-hr; 68% 4-hr; 32%, 6-hr; 3%, 8 and 10-hr. Cyst recovery rates were not different within the dosage of 50-500 cercariae per snail. Most metacercariae recovered 1-2 days after cercarial exposure were viable; only 5 among 6,533 cysts were dead.     

Parthenogenetic generations of Helicometra fasciata Rud., 1819 (Trematoda: Opecoelidae) in the Black Sea molluscs Gibbula adriatica

Morphology of the Helicometra fasciata Rud., 1819 parthenogenetic generation from the Black Sea gastropods Gibbula adriatica (Phil.) was studied for the first time. Data on seasonal dynamics of the hemipopulation of daughter sporocysts are given. Daughter sporocysts of H. fasciata infest 10 +/- 0.2 % of G. adriatica (mainly specimens of larger size and elder age classes). As a rule, local microhemipopulations of daughter sporocysts castrate mollusc hosts. Reproduction of H. fasciata daughter sporocysts is asynchronous: daughter sporocysts born specimens of next sporocyst generation during autumn and winter, and then they begin producing cercaria. In winter development of the cercaria embryo is blocked. Second change of the character of the each sporocyst' posterity is impossible because of the annual life cycle of G. adriatica. Endogenous agglomeration of the H. fasciata daughter sporocysts is extremely little: individuals of next sporocyst generation develop from no more than 2 % of embryonic balls. Energy resources of the mollusc host are used by the H. fasciata daughter sporocysts mainly for producing cercaria; this fact can be interpreted as an adaptation of H. fasciata to using medium-sized, short-living mollusc hosts.     

Effect of infection with Trichobilharzia ocellata and Schistosoma mansoni on the ultrastructure of the albumen gland of their respective hosts, Lymnaea stagnalis and Biomphalaria glabrata

The albumen gland, a female accessory sex gland of pulmonate snails, produces the perivitelline fluid. The ultrastructure of the albumen glands of control and infected specimens of Lymnaea stagnalis and Biomphalaria glabrata was studied. The albumen gland of L. stagnalis contains two types of secretory cells--light (active) and dark (inactive)--and two types of supporting cells--centroacinar and myoepithelial. The secretory cells apparently represent two activity stages of one type of cell. The gland B. glabrata possesses only one secretory cell type, which alternates with one type of supporting cell. The albumen glands of L. stagnalis and B. glabrata infected at a juvenile stage were studied 4 and 14 weeks (L. stagnalis) and 4 and 9 weeks (B. glabrata) after exposure. After four weeks' infection, B. glabrata produced some egg masses, but in subsequent stages egg mass production completely coased. Infected L. stagnalis never produced eggs. B. glabrata was apparently infected at a "physiologically" more mature stage than L. stagnalis. The morphology of the albumen glands four weeks after exposure (the daughter sporocyst stage) is in agreement with this hypothesis. At this interval the secretory cells of L. stagnalis appeared to be much more severely affected (inactive Golgi bodies and rough endoplasmic reticulum, crinophagy of the secretory granules) than the cells of B. glabrata. In the later stages studied (shedding of the cercariae), the glands of both species appeared to be completely inactive (reduced height of the epithelium, inactive organelles, crinophagy, absence of secretory granules). At this stage of infection, daughter sporocysts containing cercaria embryos were seen in the connective tissue of the albumen gland of B. glabrata, but not of L. stagnalis. The results thus indicate that the development and synthetic activity of the albumen gland are seriously affected by infection. These processes are known to be under the endocrine control of the female gonadotrophic hormones. Since it has been established that these hormones are normally present in the haemolymph of infected snails, the findings can be explained by assuming that the parasite interferes in some way or other with the snail's endocrine system.     

The Ultrastructure of the Daughter Sporocyst Tegument of Cercaria vaullegeardi Pelseneer (Digenea, Hemiuridae)

The body wall of the daughter sporocyst of Cercaria vaullegeardi Pelseneer, 1906 is unusual for a species without a birth pore in consisting of an outer anucleated, microvillous syncytial tegument and a cellular subtegument which lacks secretory cells. In contrast, most other known daughter sporocysts without birth pores have a nucleated region above the microvillous region of the tegument. The significance and functional aspects of this structure are discussed.     

青海高原二种双腔吸虫尾蚴腺体组织化学的比较观察

本文报道应用组织化学反应方法观察了青海高原中华双腔吸虫尾蚴及暂称为“B”型双腔尾蚴(可能是枝双腔尾蚴)二种单细胞腺体的组化成分及其生理功能。大单细胞腺体12—13对,内含丰富的碳水化合物——蛋白质复合物象粘蛋白之类物质,及酸性粘多糖。小单细胞腺3对,含结合氨基的蛋白质及甲性糖蛋白。二种双腔吸虫在贝类宿主体内子胞蚴及尾蚴组化威分很相似但从尾蚴粘液腺的结构可以区分二虫种。中华双腔吸虫粘球内包绕在尾蚴体外的粘液含丰富的粘蛋白。双腔吸虫幼虫期组化成分与阔盘吸虫相应的幼虫期进行了比较。     

Emergence of the cercariae of Gorgoderina vitelliloba from daughter sporocysts

The daughter sporocyst of Gorgoderina vitelliloba develops attached to the gills of its molluscan host, Pisidium. It has a conical attachment structure at one end of its body through which the birth pore opens. Cercariae emerge through the birth pore, their passage being apparently lubricated by copious secretions from the stylet glands. Only after emergence does the anterior tail chamber envelop the cercarial body to form the typical cystocercous cercaria. When sporocysts were freed from gill tissue and maintained in vitro, cercariae failed to escape from the sporocyst and several encysted, in situ. It is suggested that if this occurred naturally a different host range would be encountered and the long term result might be the evolution of a new species.     

Schistosoma mansoni: development of the cercarial glycocalyx

The development of the cercarial glycocalyx of Schistosoma mansoni was studied by transmission electron microscopy and immunofluorescence light microscopy employing antibodies raised against extracted and chromatographed glycocalyx. By electron microscopy, cercariae present in the brood chamber of daughter sporocysts were surrounded by an electron-dense granular and fibrillar matrix. This material appeared structurally distinct from the glycocalyx which was coarsely fibrillar and located only on the surface of organisms that had developed a final tegument. The thickness of the glycocalyx apparently increased with the maturation of the tegument, since teguments that had many spines also had the thickest glycocalyx. Immunofluorescent staining of frozen sections of infected snail hepatopancreas showed that glycocalyx antigens were present on the surface of the cercariae and not in the matrix within the brood chamber or in snail tissues. Immunofluorescent staining of isolated larval cercariae showed staining of some but not all parasites with partially elongated tails. These studies suggest that the glycocalyx develops late in cercarial development (late in Stage 6 or in Stage 7 of Cheng and Bier), is made by the cercariae themselves, and is not a product of either the sporocyst wall cells or snail hepatopancreas.     

Up to what point are cercariogenesis and sporocystogenesis reversible in schistosomes?

A study of larval development of Schistosoma haematobium in the snail Planorbarius metidjensis infected by transplanted sporocysts showed that some embryos in daughter sporocysts have characters intermediate between cercariae and sporocysts. These embryos are interpreted to be nearly mature cercariae that have partially reverted to be secondary sporocysts. If this explanation is correct, it would mean that the embryos which develop within trematode daughter sporocysts can differentiate either into cercariae or into a new generation of sporocysts, but originate from a single type of germinal cell.     

An ultrastructural study of the early cercarial development in Prosorhynchoides borealis (Digenea: Bucephalidae) with special reference to formation of the primitive epithelium

Primitive epithelium and outer tegumental layer formation during early cercarial development was studied in Prosorhynchoides borealis using electron microscopy. It demonstrated that germinal cells freely floating in the sporocyst body cavity divide to give rise to naked cell aggregates. These early embryos are highly irregular in outline and are composed of blastomeres differing in size and structure. In embryos consisting of about 12-14 cells a few (possibly only two) superficial macromeres become concave and produce thin extensions which envelop the embryonic mass before fusing to form a syncytial primitive epithelium. This primitive epithelium forms syncytial connections with underlying embryonic cells. Primordial tegumental cells become apparent in late germinal balls below the primitive epithelium. These cells expand and fuse to give rise to an embryonic nucleated tegument. The embryonic tegument is connected to peripheral embryonic cells by thin cytoplasmic bridges until the basement lamina is formed. Subsequently, the primitive epithelium is shed by the embryos and the nuclei in the embryonic tegument undergo pyknotic degeneration. These results are analysed and compared with data from studies on other trematode species and it is concluded that the primitive epithelium is derived from the embryo in at least the majority of digeneans.