[Paradoxical embolism: clinical situation and approaches to treatment].

The authors describe two clinical cases of paradoxical embolism of greater-circulation vessels in patients with thrombosis of deep veins of the lower extremities and patent foramen ovale, also discussing different variants of clinical course of paradoxical embolism, as well as approaches to treatment and prevention.

[Reproduction of trematode Leucochloridium paradoxum sporocysts (Trematoda: Leucochloridiidae)].

The histological study of the trematoda sporocysts Leucochloridium paradoxum confirmed the presence of three morphological zones in it: 1) central part (reproductive), where embryos are forming, 2) narrow tubes through which the embryos penetrate in colored broodsacs (3), where the development of metecercaria completes. It was found that germinal mass only is the reproduction organ of the sporocysts, located in reproductive zone. There are young (without embryos), mature (with embryos) and degenerated germinal masses. So, in the process of sporocysts development the centre of multiplication of germinal elements was changed. The old parts of central part are degenerated, but the new ones with young germinal masses appear. The multiplication of generative elements does not take place in the broodsacs which are breeding cameras functionally.

[Morphoprocess and life cycles of organisms].

In developing the ideas of V.N. Beklemishev about an organism as a form, existing in a process of determined transformation and matter/energy exchange, we consider different aspects of the term "morphoprocess" and introduce corresponding additional terms. Momentary morphoprocess characterizes an organism in the given moment of time. This term reflects a constancy of the form ("momentary form"), where the existence of an organism can be imagined as a sequence of "momentary forms". "First derivative" of this momentary characteristic is particular morphoprocess--an organism from its origin to fission/division or death. Compound particular morphoprocess is a determined and reiterating sequence of different particular morphoprocesses. And, at last, general morphoprocess--a "second derivative" of momentary morphoprocess--is rhythmical reiteration of a particular morphoprocess on the long-term scale, an ancestors/descendants lineage. To describe consecutive changes in this material system, the terms ontogenesis and life cycle are used. Ontogenesis characterizes a sequence of the morpho-functional changes of an individual organism during its life, whereas life cycle reflects a sequence of changes during one complete segment of the general morphoprocess represented by a single or several particular morphoprocesses. We also discuss morphoprocess uniformity along with the phase nature of morphoprocesses, both particular and compound particular ones.

[Reproduction of the trematode Echinostoma caproni parthenites (Digenea: Echinostomatidae)].

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.

[Development of the partenitae infrapopulation of Echinostoma caproni (Digenea: Echinostomatidae)].

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.

[Morphology and chaetotaxy of Sanguinicola armata cercaria (Trematoda: Sanguinicolidae)]. / Morfologiia i khetotaksiia tserkarii Sanguinikola armata (Trematoda: Sanguinicolidae).

A morphological description of Sanguinicola armata cercaria is given. This larva belongs to the group of brevifurcate and apharingeal cercariae. Mouth opening is on ventral surface of the anterior organ. The body and branches of the furca bear a membrane. The body/tail ratio is much more than in other cercariae of the family Sanguinicolidae. The gland apparatus of the larva is represented by several types of secretory cells. The penetration glands form a group of 5 pairs of cells on the ventral side. Their ducts form a single bunch directed anterior, go through the anterior organ and open terminally on the proboscis, which is able to turn outside. Other gland cells apparently represent specialized cytones of the tegument. Excretory formula: 2[(1 + 1) + (1 + 1)] = 8. The external surface of the larva bears a small number of sensilla. Some similarities of the families Sanguinicolidae and Schistosomatidae in the cheatotaxy of cercaria have been noticed.

[Dynamics of infection of Bithynia tentaculata (Gastropoda: Prosobranchia) with trematodes]. / Dinamika zarazhennosti Bithynia tentaculata (Gastropoda: Prosobranchia) trematodami.

The dynamics of infection of Bithynia tentaculata with 7 trematode species was examined during 5 years. Stability of parasite fauna with significant changes of infection rate has been recorded. During the period of observations the infection rate of Sphaeridiotrema globulus, Notocotylus imbricatus, Holostephanus volgensis, Pleurogenoides medians and Metorchis intermedius has decreased, while that of Psilotrema tuberculata has increased. The infection rate of Plagiorchis sp. slightly fluctuated. It was found out that the infection rate of S. globulus, P. tuberculata, Plagiorchis sp., H. volgensis and M. intermedius increases by the age of hosts. Maximal infection rate of N. imbricatus was observed in mollusks of 2-3 years old. Based on peculiarities of infection dynamics during the year, 3 groups of parasites have been recognized. 1. S. globulus, P. tuberculata and N. imbricatus show an increase of infection rate from April to August with subsequent decrease. 2. Infection rate of H. volgensis increases during the Summer and reaches maximum in Autumn. Age group of host 2+ and older ones showed some decrease of infection in the beginning of Summer. 3. First cases of infection with M. intermedius occur in May, then the infection rate increases and reaches maximum in the end of July. The infection rate gradually decreases and in the end of October the mollusks infected with M. intermedius are usually absent. An emission of cercariae is usually observed in June-August. The difference in infection rate of Bithynia tentaculata males and females was not found. Based on a complex analysis of infection dynamics and population dynamics of mollusks, different aspects of the life cycle of parasites (periods of emission, maturity and longevity of local microhemipopulations) are discussed.

[Parthenogenetic generations of Sanguinicola armata (Trematoda: sanguinicolidae)]. / Partenogeneticheskie pokoleniia Sanguinicola armata (Trematoda: Sanguinicolidae).

Daughter sporocysts of Sanguinicola armata are represented by several generations, changes of which goes synchronously with the changes of year seasons. Young individuals beginning the reproductions form exclusively cercariae. The old sporocysts begin to produce sporocysts only. These young sporocysts do not quite the organism of the old sporocyst. Therefore, series of sporocysts inside other sporocysts are often observed in hystological cross-sections. Germinal masses of daughter sporocysts of S. armata have some specific characters, which are not observed in analogous organs in daughter sporocysts of other trematode species.

[The organization of germinal material and dynamics of mother sporocyst reproduction in the genus Echinostoma (Trematoda: Echinostomatidae)]. / Organizatsiia germinal'nogo materiala i dinamiki razmnozheniia materinskikh sporotsist roda Echinostoma (Trematoda: Echinostomatidae).

The reproduction in the first parthenogenetic generation--mother sporocyst (MS) in two species of echinostomes (E. caproni, E. paraensei) is investigated. A group of densely packed cells, which noticeably differ from others, occupies the posterior part of the miracidium. They are characterized by large sizes and a large bubble-shaped nucleus with heterogeneous nucleolus and strong dispersed chromatin. The use of histological and electron microscopic methods has shown that with observed similarity these cells are classified in two tyoes and have a completely different origin. First of all, large secretory cells stand out. In E. caproni miracidia their number averages 6.8 +/- 0.2 and linear sizes is 10-12 microns. Secretory cells possess a large bubble-shaped nucleus. The caryoplasm looks optically empty because of strong dispersion of chromatin. A large nucleolus occupies a bit eccentric position. Eosinophilic cytoplasm contains poorly noticeable at light-optical level accumulation of small granules. The second group of cells is represented by typical germinal cells (GC). The number of GC does not exceed six. Their polymorphy is well above that of secretory cells. The sizes of GC vary from 5.4 to 9 microns. The largest cells (8.1-9 microns) occupy the front position and usually are located between secretory cells. Intensively basophilic cytoplasm surrounds bubble-shaped nucleus with a large nucleolus like border with uniforming thickness. The heterochromatin is evenly distributed over the caryoplasm. Its content of nuclei is more than that in nuclei of secretory cells. That is why they do not look optically empty. So, it is "mature" germinal cells. Four or five cells are located directly behind "mature" cells. Their sizes are gradually decrease towards the posterior of the miracidium (the diameter of the smallest cells reaches 5.4 microns). Nuclei with a centrally located nucleolus are characterized by larger amount and more condensation of the heterochromatin than those in "mature" cells. Meanwhile, they concern to nuclei of bubble-shaped type. In general, all cells of second type represent the primary germinal cells distinguished by the stage of their differentiation. Also, 2-3 undifferentiated cells occupy the most posterior part of the miracidium. Their sizes average 5.55 +/- 0.18 microns. The nucleus contains a lot of densely packed heterochromatin. On parasitic phase of MS development undifferentiated cells give rise to secondary GC. Electron microscopic data in details confirm the situation described above. The essentially similar results were received during the investigation of E. Paraensei miracidia. The differences are observed in parameterical characteristics of germinal material and in small variability of the extent of germinal material development. With E. paraensei, germinal material may be represented by not only GC and undifferentiated cells, but one germ as well. So, our investigation has shown that germinal material of echinostomes represents typical germinal mass. The germinal material condition does not change on parasitic phase of E. caproni MS development during the first day of post infection (PI). The activization of germinal material coincides in the time with the beginning of schizocoel formation in 2 Days PI. On the 3rd day of PI, the proliferation of undifferentiated cells begins and the first germs are free to float in enormous schizocoel. After 8 days of PI, MS release the first rediae. During the following 2-3 days the other rediae formed by primary GC left MS. The release of rediae derived from secondary GC was observed later. So, E. caproni MS give rise to 12-16 rediae which is much less than the number of GC formed in MS. The earlier release of the first E. paraensei rediae by MS is predetermined by the difference in the structure of germinal mass in E. paraensei miracidia. Therefore, Echinostomatidae is intermediate between two groups of trematodes. The first group has MS that completely realize reproductive function in the time of miracidial formation; but the second group includes higher trematodes characterized by the transfer of reproductive time on a parasitic phase of MS development. The question concerning to so-called "pedogenetic larvae of trematodes" is discussed.

[On the development of body-wall musculature Diplostomum chromatophorum metacercariae (Trematoda: Diplostomidae)]. / Razvitie myshechnykh élementov kozhno-muskul'nogo meshka metatserkarii Diplostomum chromatophorum (Trematoda: Diplostomidae).

The body-wall musculature of invasive cercariae and metacercariae of Diplostomum chromatophorum at different intervals after the penetration into the experimental intermediate host Cyprinus carpio (1, 3, 5, 6, 7, 10, 12, 20, 34, 40 days) has been investigated with the help of TEM technique. During the first 10 days after the invasion (in conditions of our experiment), the cercarial subtegumental muscle fibres degenerate. These muscles are replaced by newly formed ones. Mass differentiation of myoblasts beneath the tegument was observed in 7-10-day-old metacercariae. Obtained data indicate the metamorphosis of body-wall musculature during the morphogenesis in Diplostomum chromatophorum metacercariae.

[The organizational characteristics of the generative material and the the proliferative dynamics of trematode mother sporocysts]. / Osobennosti organizatsii generativnogo materiala i dinamika razmnozheniia materinskikh sporotsist trematod.

Analysis of miracidia germinal material organization and proliferation dynamics of mother sporocysts enabled us to divide them into three well-defined groups. The first one includes species whose miracidia possess only differentiated (mature) generative cells and embryos of earlier stages of cleavage. In this case during parasite phase of development of maternal sporocysts the generative function is not performed. To the first group therefore trematode species with pedogenetic larvae could be attributed also. The next group embraces species whose miracidia as well as mature generated cells have some undifferentiated cells; thus the parasitic phase of mother sporocyst development acquires restricted proliferative capacity. The third group consists of species with higher trematodes dominating. They perform generative function exclusively at parasitic phase of mother sporocyst development. Representatives of more archaic and ancient species are the bases of the first two groups on the contrary. Such type of distribution can not occur occasionally and apparently reflects first steps of emergenes of parthenogenetic generations of trematodes.