ABSTRACT
Dynamics of reproduction of the Notocotylus imbricatus (Notocotylidae), Echinostom caproni (Echinostomatidae), Sphaeridiotrema globulus and Psilotrema tuberculata (Psilostomatidae) rediae was examined. Forming of germinal mass in trematodes is considered and discussed on the base of literary and original data.
Subject(s)
Germ Cells/ultrastructure , Gonads/diagnostic imaging , Trematoda/ultrastructure , Animals , Germ Cells/physiology , Gonads/physiology , Trematoda/physiology , UltrasonographyABSTRACT
Dynamic of the reproduction of the trematodes Notocotylus imbricatus (Notocotylidae), Echinostoma caproni (Echinostomatidae), Sphaeridiotrema globulus and Psilotrema tuberculata (Psilostomatidae) parthenites was observed. The formation of generative cells takes place only as a result of undifferentiated cells proliferation and following differentiation. These processes and early stages of embryogenesis are taking place only in the special reproductive organ--germinal mass. The germinal mass is always formed at the posterior part of the body. The process of reproduction had been finishing to the beginning of the generating of cercariaea of new age by parthenites. Rediae of different generations in fact stop producing new generative cells with the beginning of the appearance of a new generation.
Subject(s)
Cercaria/physiology , Embryo, Nonmammalian/embryology , Embryonic Development/physiology , Trematoda/physiology , Animals , Cercaria/ultrastructure , Embryo, Nonmammalian/ultrastructure , Reproduction/physiology , Trematoda/ultrastructureABSTRACT
Dynamics of the reproduction in the trematode Echinostoma caproni parthenites (Echinostomatidae) was observed. Early laying and maturation of the generative cells are for the first time shown to be characteristic for all parthenogenetic generations. Really the process of reproduction had been finishing to the beginning of the generating of new age by parthenites. Mother sporocysts, as well as redia of different generations, in fact stop producing new generative cells with the beginning of the generating of new age, and assume the function of a brood pouch. This feature was considered previously as peculiar mainly to mother sporocysts. Data on the autotomy of the anterior body end in mother sporocysts are verified. In our opinion, these data are an evidence of an early manifestation of the evolutionary trend to the morpho-functional regress and disintegration of the parasitic stage of mother sporocyst.
Subject(s)
Echinostomatidae/growth & development , Animals , Echinostomatidae/ultrastructure , Microscopy, Electron, Scanning , Mollusca/parasitology , ParthenogenesisABSTRACT
New data on the migration and development of Echinostoma caproni mother sporocysts in two mollusk species of the genus Biomphalaria are obtained. It is confirmed, that the formation of primary and second generative cells takes place only as a result of undifferentiated cells' proliferation and following differentiation of some of them. These processes in miracidium, as well as in the parasitic stage of mother sporocyst, take place in a special organ, germinal mass, which occupies caudal position in both cases. The supposition of the role of germinal mass as the universal centre of multiplication and development of generative elements in all generations of Echinostoma caproni parthenites is confirmed. It is established, that mother sporocysts do not relize their reproductive potential completely, and the degree of its realization depends on the conditions arising in the host organism.
Subject(s)
Echinostoma/embryology , Host-Parasite Interactions , Snails/parasitology , Animals , Echinostoma/cytology , FemaleABSTRACT
The first generation of Echinostoma caproni partenitae is represented maternal sporocysts developing in the cardium of the Biomphalaria mollusk. During all their life, they produce rediae of maternal generation. Rediae of Echinostoma caproni of all generations are similar. The first generation consists of maternal rediae forming only redoid embryos. Due to this process, the number of partenitae increases very fast. The next generations are represented by daughter rediae. In the beginning of their life they produce redoid embryos but later begin forming cercariae. The number of rediae produced before this shift of production depends on the population density. Further, the partenitae retain their potential ability to form rediae but realize it in exceptional cases. Generative organs of all generations are germinal masses. Proliferation of generative elements and beginning stages of redia and cercaria development take place within these masses. The infrapopulation of E. caproni belongs to the "prolonged type", because it is a complete microhemipopulations; its existence is limited by a lifespan of the mollusk host.
