Acta Parasitologica, Vol. 52, No. 1, 2007, 31-50. 10.2478/s11686-007-0006-3 Zdzisław Świderski (1, 2)*, Jordi Miquel (3), Daniel Młocicki (1, 4), Boyko B. Georgiev (5, 6), Catarina Eira (3),
Barbara Grytner-Zięcina (2) and Carlos Feliu (3) - Post-embryonic development and ultrastructural
characteristics of the polycephalic larva of Taenia parva Baer, 1926 (Cyclophyllidea, Taeniidae)
(1) W. Stefański Institute of Parasitology, Polish Academy of Sciences, 51/55 Twarda Street, 00-818 Warsaw, Poland;
(2) Department of General Biology and Parasitology, Medical University of Warsaw, 5 Chałubińskiego Street, 02-004 Warsaw, Poland;
(3) Laboratori de Parasitologia, Departament de Microbiologia i Parasitologia SanitBries, Facultat de FarmBcia, Universitat de Barcelona, Av.
Joan XXIII s/n, E-08028 Barcelona, Spain;
(4) Department of Medical Biology, Medical University of Warsaw, 73 Nowogrodzka Street, 02-004 Warsaw, Poland;
(5) Central Laboratory of General Ecology, Bulgarian Academy of Sciences, 2 Gagarin Street, 1113 Sofia, Bulgaria;
(6) Department of Zoology, The Natural History Museum, Cromwell Road, London SW7 5BD, UK
*Corresponding author: z.swider@twarda.pan.pl
ABSTRACT
Post-embryonic development and fully-formed polycephalic larvae of Taenia parva Baer, 1926 were examined by light (LM)
and transmission electron microscopy (TEM). Three developmental stages were recognised: (1) an early stage of exogenous
budding at the surface of the central vesicle; (2) a stage of polycephalic cyst development accompanied by segmentation of
the growing larval strobile and an obvious decrease in the size of the central vesicle; (3) fully-formed larval strobile and invaginated
scoleces. In fully-developed encysted polycephalic larvae, there are usually 14-24 segmented larval strobilae, each terminating
with an invaginated scolex; larval strobilae arise from a common central vesicle and remain attached posterior to it
during the entire development. The number of segments varies between 109 and 120 per larval strobila. The polycephalic larvae
examined closely resemble the strobilocercus type of taeniid larvae. The structure of developing and fully-formed larvae
was examined by TEM. The tegument, scolex, subtegumental musculature of the strobilar segments, protonephridial system,
calcareous corpuscles and medullary parenchyma of larvae exhibit general similarity with the same structures in adults at both
LM and TEM levels. The morphogenesis of the larva of T. parva is compared with that of the polycephalic larvae of other Taenia
spp. (T. krepkogorski, T. twitchelli and T. endothoracica) and with other asexually-multiplying cestode larvae (mesocestoidids,
hymenolepidids and dilepidids).
KEY WORDS: Cestoda, Taenia parva, polycephalic larva, post-embryonic development, ultrastructure