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Comparative ultrastructure of fertilization in parasitic platyhelminthes

100%

Swiderski Z., Conn D. B.

Wiadomości Parazytologiczne

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1998

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tom 44

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nr 3

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Ultrastructural aspects of fertilization in Proteocephalus longicollis, Inermicapsifer madagascariensis, and Mesocestoides lineatus [Platyhelminthes, Cestoda]

80%

Swiderski Z., Conn D. B.

Acta Parasitologica

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1999

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tom 44

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nr 1

Ultrastructural aspects of fertilization were studied in three cestode species: one proteocephalid with biflagellate spermatozoa, Proteocephalus longicollis, and two cyclophyllideans with uniflagellate spermatozoa, Inermicapsifer madagascariensis (Anoplocephalidae) and Mesocestoides lineatus (Mesocestoididae). Fertilization in all three species occurs in the oviduct lumen or in the fertilization canal proximal to the ootype, where the formation of the embryonic capsule precludes sperm contact with the oocyte. Cortical granules are not present in the oocytes of any of the three species. Spermatozoa coil spirally around the oocytes and syngamy occurs by lateral fusion of oocyte and sperm plasma membranes. In the ootype one (Proteocephalus and Inermicapsifer) or two (Mesocestoides) vitellocytes associate with the fertilized oocyte, forming a membranous capsule which encloses both cell types. In this stage, spirally coiled sperm flagella adhere partly to the external oocyte surfaces, and partially penetrate into the perinuclear cytoplasm. Usually, several loops of the spermatozoon occur within the oocyte cytoplasm. The electron-dense sperm nucleus within the oocyte cytoplasm becomes progressively electron lucent after penetration. Simultaneously with chromatin decondensation, the elongate sperm nucleus changes shape, forming a spherical male pronucleus, which attains the size of the female pronucleus. Cleavage begins immediately after pronuclear fusion.

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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

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2002

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tom 47

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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

1 Wiadomości Parazytologiczne

3 Swiderski Z.

2 Conn D. B.

1 Tkach V. V.

1 2002

1 1999

1 1998

Comparative ultrastructure of fertilization in parasitic platyhelminthes

Ultrastructural aspects of fertilization in Proteocephalus longicollis, Inermicapsifer madagascariensis, and Mesocestoides lineatus [Platyhelminthes, Cestoda]

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