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Fine structure of the infective eggs of the dilepidid cestode Hepatocestus hepaticus [Baer, 1932], a parasite of shrews

100%

Swiderski Z., Tkach V. V., Vaucher C.

Acta Parasitologica

2000

tom 45

nr 2

Ultrastructural characteristics of the eggs of the dilepidid cestode, Hepatocestus hepaticus, is described. The mature oncosphere is surrounded by three envelopes: (1) an outer envelope; (2) an inner envelope consisting of three layers - an extraembryophoral cytoplasmic layer, a thick, fibrillar, low electron-dense embryophore, and intraembryophoral cytoplasmic layer, (3) a thin oncospheral membrane, surrounding the oncosphere. The whole surface of the oncosphere is covered by the cytoplasmic oncospheral tegument with numerous short microvilli and a layer of subtegumental somatic muscles. The following cell types were distinguished in the mature oncospheres: the U-shaped penetration gland a containing a large amount of tightly packed secretory granules; bi-nucleate perikaryon of the oncospheral tegument; somatic cells (= myocytons of somatic and hook muscles); and the germinative cells. The hook-muscle system consists of three pairs of embryonic hooks and a complex system of specialised muscle fibers responsible for the coordinated hook movements. The ultrastructural characteristics of H. hepaticus oncosphere are discussed in comparison with those of previously studied dilepidids and other cyclophyllideans.

Ultrastructure of embryonic development of Inermicapsifer madagascariensis [Cestoda, Anoplocephalidae] with emphasis on the cellular organisation of the infective eggs

80%

Swiderski Z., Tkach V. V.

Acta Parasitologica

2002

tom 47

nr 2

The cellular organisation of the infective eggs of I. madagascariensis has been reconstructed at light (LM) and electron microscopy (EM) level from serial semithin (LM) and ultrathin sections (EM). The oncospheres are surrounded by parenchymatic capsules. The total number of oncospheral cells' is about 44 (50 nuclei). Among them, five major cell types have been distinguished. These consisted of: (1) a six-nucleate, U-shaped penetration gland; (2) a bi-nucleate medullary centre (= sunken perikaryon of oncospheral tegument); (3) two nerve cells of neurosecretory type; (4) about 30 somatic cells (= myocytons of hook and somatic musculature); and (5) about 12 germinative cells (two groups of 6 cells), localised in the posterior pole of the hexacanth. The functional ultrastructure of hook-muscle system and penetration gland and their role in host tissue penetration are discussed.

Ograniczanie wyników

2 Acta Parasitologica

2 Swiderski Z.

2 Tkach V. V.

1 Vaucher C.

1 2002

1 2000

Wyniki wyszukiwania

Fine structure of the infective eggs of the dilepidid cestode Hepatocestus hepaticus [Baer, 1932], a parasite of shrews

Ultrastructure of embryonic development of Inermicapsifer madagascariensis [Cestoda, Anoplocephalidae] with emphasis on the cellular organisation of the infective eggs