Volume 49/Number 3/Abstract 7
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Acta Parasitologica, Vol. 49, No. 4, 2004, 300-308
Zdzislaw Swiderski(1,2)*, Ruslan V. Salamatin(2,3), Barbara Grytner-Ziecina(2), Vadim V. Kornyushin(3) and David Bruce Conn(4) - Electron microscope study on oncospheral envelope morphogenesis in the dilepidid cestode, Dilepis undula (Schrank, 1788)

(1)W. Stefanski Institute of Parasitology, Polish Academy of Sciences, 51/55 Twarda Street, 00-818 Warszawa; (2)Department of General Biology and Parasitology, Medical University of Warsaw, 5 Chalubinskiego Street, 02-004 Warszawa; Poland; (3)I. Schmalhausen Institute of Zoology, National Academy of Sciences of Ukraine, 15 Khmelnitsky Street, MSP, 01601 Kiev, Ukraine; (4)School of Mathematical and Natural Sciences, Berry College, Mount Berry, Georgia 30149-5036, U.S.A.
*Corresponding author: z.swider@twarda.pan.pl

The origin, differentiation and ultrastructural characteristics of oncospheral envelopes surrounding invasive oncospheres of the dilepidid cestode Dilepis undula are described. In the early preoncospheral phase three primary embryonic envelopes are formed: (1) the capsule; (2) the outer envelope formed by two macromeres; and (3) the inner envelope originating from fusion of two or three mesomeres. Both the outer and inner envelopes of D. undula are therefore cellular in origin and syncytial in nature. Mature eggs of D. undula are slightly oval, measuring 40-50 56 um in diameter. Within fully formed eggs, the mature, invasive oncospheres, 36-40 um in diameter, are surrounded by five oncospheral or egg envelopes: (1) outer shell; (2) outer envelope; (3) inner envelope; (4) oncospheral membrane; and (5) hook region membrane covering only one pole of the hexacanth. The ultrastructural characteristics of D. undula oncospheral envelopes are discussed in comparison with those of previously examined dilepidids and other cyclophyllideans.

KEY WORDS: Dilepis undula, Dilepididae, Cestoda, oncospheral envelopes, morphogenesis, cestode eggs, ultrastructure

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