Developmental Biology Of Cysticercus Cellulosae And Mechanism Of Action Of Drugs

T.solium cysticercosis is an important parasitic zoonosis endangering the development of husbandry and healthy of human. In order to select an effective medicine against cysticercosis and to provide a theoretical basis for chemotherapy, the author studied firstly and systematically development of cystieerei in vivo and in vitro and the effect of drugs on cysticerci in different developmental stages. By optical microscope and electronic microscope the morphology and structure of cysticerci were observed in detail.A technique, in situ endabelling, was applied to detect qualitatively and quantitatively the apoptotie cell positive index (Al) in cysticerci and hosts. In combination with the detection of the levels of nitric oxide (NO) and AT of lymphocyte (LI), the clinal genesis of cysticercosis and possible mechanism of action of the drugs against cysticerci were analyzed. The results were showed as follows(1)An in vitro culture system incorporating a cell monolayer without gas phase was firstly used to induce most of the oncospheres of T. solium to enter postncosperal development. The larval can survive for 16 days.(2)ln vitro hatched oncospheres were injected intravenously into the mice. The mice were autopsied 2 months after inoculation. Cysticerci were found in the lung and 56 percent mice were infected. The mice infected intravenously by oncospheres are valuable experimental animal models for studying T. solium cysticercosis. (3)Changes of morphology, histological structure and ultrastructure of C. cellulosae in the development were firstly and systematically studied. The size of eysticerci in the same host were variable. The youngest cysticerci observed were 19 days old, but suckers and hooks were not found in scolex region. Histology showed that a lot of cells accumulated at one of the poles and at the proliferation region the tegument invaginated. With the duration of infection, scolex began to differentiate and possessed suckers and hooks. During the development the bladder wall is a transitory embryo, on the basis of which the scolex develops. 60 days later, most of cysticerci were mature. The ultrastructure showed the components of eysticerci increased in number and extent but no new cells or tisssues appeared as the cysticerci grew.Bladder wall and scolex had some differences in ultrastructures. The bladder wall seems to have different functions from scolex. The bladder wall might function in the absorption of nutrition, while the scolex was concerned with the future development.(4)It was firstly studied that apoptosis occured during the development of cysticerci.With the duration of infection Al decreased.80 days later,AI increased a little and then keeped in a stable level. When considering the relationships among NO level in the host, L桝I in the host and Al of cysticerci, the author found a strong positive correlation between NO level in the host and Al of cysticerci and a strong negative correlation between L桝I in the host and Al of cysticerci.(5)Drugs were selected firstly on the basis of studying the development of C. cellulosae. Both NX1 and NX2 ,which had been selected in vitro, were used in vivo to eliminate premature and mature cyst icerci. The results showed NX1 was effective against premature and mature cysticerci and had a better effect against the former, but NX2 was ineffictive against cysticerci in the two developmental stages.(6)After NX1 was applied in vitro for 72 hours, most of the cells in premature and mature cysticerci underwent apoptosis and necrotic cells infrequently appeared. After NX, was applied in viva for 1 day, the cells in premature and mature cysticerci also underwent apoptosis. But most of the cells in premature cysticerci underwent necrosis after NX~ was applied for 2 days in vivo and as did those in mature cysticerci the tenth day. After applied in viva, NX results in cell apoptosis of cysticerci first and then necrosis appears under the involvement of some factors from hosts.(7)According to the ultrastructural observations,absorptive and sec...