ELECTRON-MICROSCOPE STUDIES ON DEVELOPMENTAL STAGES OF THEILERIA PARVA (THEILERIA, 1904) IN INTESTINE OF TICK HYALOMMA ANATOLICUM EXCAVATUM (KOCH, 1844)

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  • 1 January 1976
    • journal article
    • research article
    • Vol. 27  (2) , 182-191
Abstract
The developmental stages of T. parva within the intestine of ticks were studied by EM. On the 2nd-4th day post repletion (p.r.) the intestine of the ticks contained numerous stages, similar to microgamonts and microgametes of hemosporidia. Gamogony of T. parva apparently takes place in the intestine of ticks, too. The microgamont-like stages were spear-head-like; they measured about 10.5 .mu.m in length with a maximum diameter of about 2.1 .mu.m in their middle region. These parasites, limited by a unit membrane, had a stiletto-like apex, several flagellar-like protrusions of about 3 .mu.m in length and mostly 2 slender posterior protrusions. The stiletto-like structure was electron-dense and measured about 2.0 .mu.m in length; at its base it appeared spongy consisting of coiled, fibrillar elements of about 20 nm in diameter. Up to 4 flagellar-like protrusions were found in cross sections originating near the base of the stiletto-like structure. At most, up to 6 microtubules were seen within these protrusions, which at their free ends usually contained only 2 microtubules. Near the base of the stiletto-like structure 2 groups of additional microtubules began. One group ran beneath a 3rd of the peripheral margin to the posterior cell pole. The other group was bundle-like arranged. In cross sections through the posterior slender protrusions of the parasite about 10 microtubules appeared in an irregular pattern. The slender posterior protrusions had nearly double dimensions of the flagellar-like protrusions. The thicker middle region of the parasites was characterized by up to 4 nuclei with large nuclear spaces. Nearby, several double-membraned organelles were seen as well as a large vacuole of about 1.3 .mu.m in diameter containing granular material. Up to 20 electron dense granules of about 0.05 .mu.m in diameter were spread between the typical ribosomes and several lacunes of the endoplasmic reticulum. The microgamete-like parasites were cord-shaped with a central thickening caused by the nucleus. Within these 9-11 .mu.m long parasites several microtubules ran from 1 end to the other. A regular pattern of the microtubules was not observed.