Wyniki wyszukiwania

Wyszukiwano:
w słowach kluczowych: uniflagellate spermatozoon

Sortuj według:

Ogranicz wyniki do:

Fertilization in the cestode Gallegoides arfaai [Mobedi et Ghadirian, 1977] Tenora et Mas-Coma, 1978 [Cyclophyllidea, Anoplocephalidae]

100%

Swiderski Z., Conn D. B., Miquel J., Mlocicki D.

Acta Parasitologica

2004

tom 49

nr 2

Fertilization in the anoplocephalid cestode Gallegoides arfaai with uniflagellate spermatozoa was examined by means of light and transmission electron microscopy. Fertilization in this 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 cytoplasm of oocytes of this species. However, two other types of large bodies containing granular material, one of homogeneous moderate electron density and one of heterogeneous moderate electron density, are present in the perinuclear cytoplasm of the oocytes. Spermatozoa coil spirally around the oocytes and syngamy occurs by lateral fusion of oocyte and sperm plasma membranes. In the ootype, one vitellocyte associates 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 enter into the perinuclear cytoplasm. Usually, several loops of the spermatozoon occur within the oocyte cytoplasm. The electron-dense sperm nucleus becomes progressively electron-lucent within the oocyte cytoplasm after entry. 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.

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

80%

Swiderski Z., Conn D. B.

Acta Parasitologica

1999

tom 44

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.

Ograniczanie wyników

2 Acta Parasitologica

2 Conn D. B.

2 Swiderski Z.

1 Miquel J.

1 Mlocicki D.

1 2004

1 1999

Wyniki wyszukiwania

Fertilization in the cestode Gallegoides arfaai [Mobedi et Ghadirian, 1977] Tenora et Mas-Coma, 1978 [Cyclophyllidea, Anoplocephalidae]

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