Abstract
The attachment of Cryptosporidium sporozoites to Madin-Darby canine kidney (MDCK) cells was examined using transmission electron microscopy. As the anterior end of the sporozoite came into close proximity to the MDCK cell, the host cell membrane evaginated around the sporozoite, forming a parasitophorous vacuole. A dense band formed below the host cell membrane at the site nearest to the conoid. Variably electron-dense material was apparently released from the conoid and a large membrane-bound vacuole was formed in the anterior end of the sporozoite, displacing the typical anterior electron-dense organelles (rhoptries and micronemes). The outer membrane of the sporozoite pellicle then fused with the host cell membrane immediately adjacent to the conoid. The membrane surrounding the anterior vacuole was also fused with the common host-parasite membrane, forming Y-shaped membrane junctions where each limb was a unit membrane. A direct link was thereby established between the anterior vacuole of the sporozoite and the host cell cytoplasm. The anterior vacuole membrane separating the sporozoite and the host cell cytoplasm was the precursor of the feeder organelle.
Similar content being viewed by others
References
Bannister LH, Butcher GA, Dennis ED, Mitchell GH (1975) Structure and invasive behaviour of Plasmodium knowlesii merozoites in vitro. Parasitology 71:483–491
Barker IK, Carbonell PL (1974) Cryptosporidium agni sp.n. from lambs, and Cryptosporidium bovis sp.n. from a calf, with observations on the oocyst. Z Parasitenkd 44:289–298
Bommer W (1969) The life cycle of virulent Toxoplasma in cell cultures. Aust J Exp Biol Med Sci 47:505–512
Current WL, Reece NC (1986) A comparison of endogenous development of three isolates of Cryptosporidium in suckling mice. J Protozool 33:98–108
Current WL, Upton SJ, Haynes TB (1986) The life cycle of Cryptosporidium baileyi n.sp. (Apicomplexa, Cryptosporidiidae) infecting chickens. J Protozool 33:289–296
Entzeroth R (1985) Invasion and early development of Sarcocystis muris (Apicomplexa, Sarcocystidae) during penetration of cultured cells. J Protozool 32:446–453
Goebel E, Braendler U (1982) Ultrastructure of microgametogenesis, microgametes and gametogony of Cryptosporidium sp. in the small intestine of mice. Protistologica 18:331–344
Hampton JC, Rosario B (1965) The attachment of microorganisms to epithelial cells in the distal ileum of the mouse. Lab Invest 14:1464–1481
Hampton JC, Rosario B (1966) The attachment of protozoan parasites to intestinal epithelial cells of the mouse. J Parasitol 52:939–949
Jensen JB, Edgar SA (1976) Possible secretory function of the rhoptries of Eimeria magna during penetration of cultured cells. J Parasitol 62:988–992
Jensen JB, Edgar SA (1978) Fine structure of the penetration of cultured cells by Isospora canis sporozoites. J Protozool 25:169–173
Jensen JB, Hammond DM (1975) Ultrastructure of the invasion of Eimeria magna sporozoites into cultured cells. J Protozool 22:411–415
Ladda R, Aikawa M, Spinz H (1969) Penetration of erythrocytes by merozoites of mammalian and avian malarial parasites. J Parasitol 65:633–644
Marcial MA, Madara JL (1986) Cryptosporidium: Cellular localization, structural analysis of absorptive cell-parasite membrane interactions in guinea pigs, and suggestion of protozoan transport by M cells. Gastroenterology 90:583–594
Reduker DW, Speer CA (1985) Factors influencing excystation in Cryptosporidium oocysts from cattle. J Exp Parasitol 71:112–115
Scholtyseck E, Mehlhorn H (1970) Ultrastructural study of characteristic organelles (paired organelles, micronemes, micropores) of Sporozoa and related organisms. Z Parasitenkd 34:97–127
Scholtyseck E, Mehlhorn H, Friedhoff K (1970) The fine structure of the conoid of Sporozoa and related organisms. Z Parasitenkd 34:68–94
Vetterling JM, Takeuchi A, Maddern PA (1971) Ultrastructure of Cryptosporidium wrairi from the guinea pig. J Protozool 18:248–260
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Lumb, R., Smith, K., O'Donoghue, P.J. et al. Ultrastructure of the attachment of Cryptosporidium sporozoites to tissue culture cells. Parasitol Res 74, 531–536 (1988). https://doi.org/10.1007/BF00531630
Accepted:
Issue Date:
DOI: https://doi.org/10.1007/BF00531630