The International Satellite Symposium on the "Reproductive and
Developmental Biology of Parasitic Platyhelminths" was held in Olsztyn on
10 September 1998, during the 18th Jubilee Meeting of the Polish
Parasitological Society (PPS), commemorating the 50th Anniversary of its
My aim as organizer of this Symposium, on behalf of the Institute of Parasitology, Polish Academy of Sciences, was to invite the original contributions as well as pertinent but unavoidably selective reviews of recent advances in our understanding of the reproduction and development of parasitic Platyhelminthes. It is hoped that the original contributions and review papers presented at this Symposium supply not only the background of critically evaluated past work on these groups of parasites but also provide an indication of the directions in which research in this field is progressing at the moment. Some of the contributions presented there highlighted surprising gaps in our knowledge; if their publication here can stimulate further research to fill these voids, the main function of this Symposium would be partially realized. Due to a long Polish tradition in this field of research, we would like also to organize similar meetings in the future, at more or less regular intervals. The next occasion will be the 8th European Multicolloquium of Parasitology, which will take place in Poznan, Poland, between 10th and 14th September 2000.
The Polish school of parasitology (C. Janicki, L. W. Wisniewski, J.S. Ruszkowski, W. Michajlow, K. Rybicka, L. Jarecka) has a long tradition in this field of research and always significantly contributed towards its development and current progress.
The topic of the Symposium was a broad one and included papers on the spermatogenesis, vitellogenesis, fertilization, embryonic development and larval stages of all groups of parasitic platyhelminths studied by means of different methods and techniques including light and electron microscopy, cytochemistry, biochemistry and immuno-cytochemistry.
The first speaker, Professor David W. Halton, presented results of his fascinating studies on the role of the neuroactive substances in reproduction and development in Platyhelminthes. Using antisera to endogenous flatworm FMRFamide-related peptides (FaRPs) and to biogenic amine, 5-hydroxytryptamine (5-HT), comparison has been made, through confocal imaging, of the immunostaining of ootype innervation in trematodes. He showed that the neuropeptic substances may have a hormonal-like influence on reproductive development in flatworms, as well as serving to regulate motility of the ootype wall and associated ducts, essential for oviposition. The second paper on the functional morphology and ultrastructure of the eggs, uterus and paruterine capsules of Distoichometra bufonis (Cestoidea, Nematotaeniidae) was presented by Professor David Bruce Conn. His original results expanded the basis for comparing eggs and associated reproductive structures that occur among the more common cestodes of terrestrial hosts. Three other papers presented on the ultrastructure of cestode eggs were on comparative ultrastructure of some cyclophyllidean eggs (Chomicz and Walski), and the original results on infective eggs of dilepidid Hepatocestus hepaticus (Swiderski and Tkach), as well as original results on egg morphogenesis and ultrastructure in the hymenolepidid cestode, Staphylocystoides stefanskii (Tkach and Swiderski).
Professor Willi E. R. Xylander concluded his paper on larval biology of Gyrocotylidea and Amphilinidea and the evolution of Cestoda with a statement that the extremely high egg production in these parasites compensates offspring loss by lower rates of host finding due to a passive mode of infection.
The results of Professors L. Jarecka, M. D. B. Burt, and B. MacKinnon on the tegument ultrastructure of the larval forms of some Pseudophyllidea, Haplobothridea, and Cyclophyllidea may provide further evidence in support of Janicki's Cercomer Theory.
Two papers were presented on the ultrastructure and cytochemistry of Mehlis' gland and egg-shell formation in Schistosoma haematobium and Schistosoma japonicum (Moczon and Swiderski, and Swiderski, Moczon and Eklu-Natey). In both schistosome species, the glycoprotein expelled from the Mehlis' gland forms a relatively thick "cocoon" around the ovum-vitellocytes complex and apparently induces degranulation of vitelline cells (expulsion of "shell-globules" = polyphenolated proteins).
Two review papers were presented on the comparative ultrastructure of fertilization in parasitic Platyhelminthes (Swiderski and Conn) and on the comparative ultrastructure of vitellocytes and vitellogenesis in cestodes (Swiderski and Xylander). The ultrastructural studies on fertilization in parasitic flatworms are rare: two on cestodes, three on digeneans and two on monogeneans. Their results indicate that the gamete fusion in species with uniflagellate and biflagellate sperm is essentially similar. This homogeneity in flatworm fertilization patterns contrasts sharply with the great variety in their sperm ultrastructure. The second review on vitellogenesis, in particular a comparison of interrelationships which exist between types of vitellocytes, vitellogenesis, types of embryonic development, ovoviviparity and life cycles indicated parallelism and analogies in adaptation to the parasitic way of life in different groups of cestodes.
In addition to the few invited review papers, numerous authors presented original result of their recent or current research in this field in the poster session. The Symposium involved 30 participants from 8 countries of Europe, and from the USA, Canada and Senegal. The abstracts of all accepted contributions were published in the special number of Wiadomosci Parazytologiczne, vol. 44, no. 3, 1998, which was distributed to all participants at the Meeting in Olsztyn.
The publication of the selected, complete papers presented at this Symposium was in the hands of Editor in Chief of Acta Parasitologica. The style and format of the Symposium contribution correspond to those of this journal. Our original idea was to publish full versions of all selected, invited papers presented at the Symposium, in one issue of Acta Parasitologica. Due to various reasons and to our sincere regret, this was not possible and thus only 6 papers appear as review or original, reviewed papers in this issue. As some authors were already committed to publish somewhere else or they were not ready to meet the rather short deadline, their contributions will follow as regular, reviewed papers published in forthcoming issues of Acta Parasitologica.
I would like to take this opportunity to express my sincere thanks to Professor David W. Halton, Queen's University of Belfast, U.K. and Professor D. Bruce Conn, Berry College, Georgia, U.S.A., for their chairmanships of the Symposium.
My gratitude is also due to Professor Katarzyna Niewiadomska, the President of the PPS for her suggestion to schedule our Symposium as a "satellite meeting" in the framework of the 18th Jubilee Meeting of the PPS as well as for her assistance and advice in all stages of its organization.
Scientific Programme of the International Satellite Symposium:
Ultrastructure of oncospheral envelopes at the final stage of infective
egg formation in some species of Cyclophyllidea - Lidia Chomicz
and Michal Walski (Warsaw, Poland)
Functional morphology and ultrastructure of the eggs, uterus and
paruterine capsules of Distoichometra bufonis (Platyhelminthes:
Cestoidea: Nematotaeniidae) - David Bruce Conn (Mount Berry,
Neuroactive substances in reproduction and development in
platyhelminths - David W. Halton, Aaron G. Maule and Chris Shaw
Tetraphyllidean cercoid ultrastructure: Janicki's "Cercomer Theory"
revisited - Lena Jarecka, Michael D. B. Burt and Barbara M.
MacKinnon (New Brunswick, Canada)
Cell compound of parenchyma and extracellular matrices of Triaenophorus
nodulosus (Cestoda) in ontogenesis - Janetta V. Korneva
Striated rootlets in spermatids of Anoplocephaloides dentata
(Anoplocephalidae) and Dipylidium caninum (Dipylidiidae): a new
finding in the Cyclophyllidea - Jordi Miquel, Cheikh Tidiane Ba
and Bernard Marchand (Barcelona, Spain; Dakar, Senegal and
Schistosoma japonicum: the chemical nature of the secretion
the Mehlis' gland - Tadeusz Moczon and Zdzislaw Swiderski (Warsaw,
The fine structure of uterine, prostatic and Mehlis' glands of
Caryophyllidea and Cyathocephalata - Larisa G. Poddubnaya (Borok,
Implication of Phyllobothrium lactuca (Cestoda, Tetraphyllidea,
Phyllobothriidae) spermiogenesis on phylogenesis within the
Tetraphyllidea - Aminata Sene, Cheikh Tidiane Ba, Jordi Miquel and
Bernard Marchand (Dakar, Senegal; Barcelona, Spain and
Comparative ultrastructure of fertilization in parasitic
Platyhelminthes - Zdzislaw Swiderski and David Bruce Conn (Warsaw,
Poland and Mount Berry, U.S.A.)
The ultrastructure and cytochemistry of Mehlis' gland and egg-shell
formation in Schistosoma haematobium - Zdzislaw Swiderski,
Tadeusz Moczon and D. T. Eklu-Natey (Warsaw, Poland and Geneva,
Fine structure of the infective eggs of the dilepidid cestode
Hepatocestus hepaticus (Baer, 1932), a parasite of shrews -
Zdzislaw Swiderski and Vasyl Tkach (Warsaw, Poland and Kiev,
Types of vitellocytes and vitellogenesis in the Cestoda in relation to
different types of embryonic development, ovoviviparity and life
cycles - Zdzislaw Swiderski and Willi E. R. Xylander (Warsaw,
Poland and Gorlitz, Germany)
A study of egg assembly in the monogenean (plathyhelminth) fish skin
parasite, Entobdella soleae, using a fast preservation technique
and transmission electron microscopy - Tracy Tappenden and Graham
Kearn (Norwich, U.K.)
Late stages of egg morphogenesis and ultrastructure of infective eggs in
the cestode Staphylocystoides stefanskii (Cyclophyllidea,
Hymenolepididae) - Vasyl Tkach and Zdzislaw Swiderski (Kiev,
Ukraine and Warsaw, Poland)
Larval biology of Gyrocotylidea and Amphilinidea and the evolution of
Cestoda - Willi E. R. Xylander (Gorlitz, Germany)