ELECTRON-MICROSCOPIC STUDY ON THE DEVELOPMENT OF BABESIA-OVIS (PIROPLASMIA) IN THE SALIVARY-GLANDS OF THE VECTOR TICK RHIPICEPHALUS-BURSA

  • 1 January 1982
    • journal article
    • research article
    • Vol. 39  (1) , 29-40
Abstract
The formation of [the sheep parasite] B. ovis sporozoites in salivary gland cells of the vector tick R. bursa was studied by EM. The kinetics of B. ovis were intracellular on the 2nd day after infection (a.i.). The parasites enlarged rapidly losing all features of the motile form. Invaginations of the cell membrane initiated a fragmentation of this developmental stage. On teh 3rd day a.i. the parasite (measuring up to 40 .times. 25 .mu.m) was divided into numerous single membrane-bounded cytomeres, each provided with at least 1-lobed nucleus. On the 4th day a.i. sporozoite differentiation started at the periphery of the cytomeres, indicated by the appearance of several pellicle-bounded, exogenous protrusions into each of which a small portion of the nucleus was incorporated. Since the cytomeres lay very close together this differentiation occurred more by segmentation than by budding. Rhoptries and the so-called spherical body appeared in this developmental phase. Finally, the isolated, immature sporozoites lay in a granular matrix which contained remnants of the host cell cytoplasm. On the 5th day a.i. the sporozoites were fully developed, typically pear-shaped (2.8 .times. 1.2 .mu.m) and provided with all characteristic structures of the invasive form. This reproduction was compared to similar processes in other species of the Piroplasmia and the Haemosporina.