title: The fine structure of sexual stage development and sporogony of Cryptosporidium parvum in cell-free culture.
abstract: The sexual stages and new oocysts development of Cryptosporidium parvum were investigated in a cell-free culture system using transmission electron microscopy (TEM). Sexual development was extremely rapid after inoculation of oocysts into the medium. The process began within 1/2-12 h and was completed with new oocyst formation 120 h post-inoculation. The macrogamonts were bounded by two membranes and had amylopectin granules and two distinct types of wall-forming bodies. The microgamonts had a large nucleus showing lobe projections and condensation of chromatin, giving rise to peripherally budding microgametes. The microgametes contained a large area of granular substance containing groups of microtubules surrounding the electron-dense nucleus. In some instances, the dividing microgamy was observed in cell-free cultures with no preceding merogonic process. Fertilization was observed with the bullet-shaped microgamete penetrating an immature macrogamont at 24 and 216 h. The new thin- and thick-walled oocysts had a large residuum with polysaccharide granules and sporogony noted inside these oocysts. Novel immature four-layer walled thick oocysts with irregular knob-like protrusions on the outer layer resembling the immature Eimeria oocysts were also observed. The present study confirms the gametogony and sporogony of C. parvum in cell-free culture and describes their ultra-structure for the first time.
authors.affiliation: University of Cologne,Center for Anatomy,Institute I,Joseph-Stelzmann-Street 9,50937 Cologne,Germany.
authors.forename: Hebatalla M
authors.initials: HM
authors.lastname: Aldeyarbi
authors.affiliation: University of Cologne,Medical School,Cologne,Germany.
authors.forename: Panagiotis
authors.initials: P
authors.lastname: Karanis
mesh_terms: D018929:Cell Culture Techniques; D016785:Cryptosporidium parvum / Q000254:growth & development / Q000648:ultrastructure*; D005306:Fertilization; D008018:Life Cycle Stages; D046529:Microscopy, Electron, Transmission; D033661:Oocysts / Q000648:ultrastructure
keywords: Host cell-free culture; extracellular development; immature thick oocysts; sexual life cycle; thick-walled oocysts; thin-walled oocysts