PHAGOCYTOSIS OF FOREIGN ABIOTIC PARTICLES BY HEMOCYTES OF THE BLOWELY, CALLIPHORA VICINA IN VIVO. I.
DYNAMICS OF HEMOCYTE ACTIVITY DURING LARVAL DEVELOPMENT
T. V. Kind
Department of Entomology, Biological Research Institute, St. Petersburg State University,
St. Petersburg, Russia;
e-mail: : tatiana.kind@mail.ru
Three types of Calliphora larval hemocytes have been revealed to be involved in phagocytosis of
abiotic foreign particles: thrombocytoids, larval plasmatocytes and plasmatocytes I. Thrombocytoids are the quickest to respond
to the appearance of invaders. The onset of test particle entrapment by thrombocytoid cytoplasmic fragments was observed,
depending on the larval age within 0.5-5.0 min after injection. Separated fragments were fused, forming strands or roundish
agglutinates. Phagocytosis of carbon, carmine or Indian ink particles by larval plasmatocytes occurs far more lately, and no
earlier than 20-30 min after injection. Plasmatocytes I are capable of foreign particles adhesion on their surface, with a
subsequent morule formation, and of engulfing these particles. These two events start in different time periods: adhesion occurs
in 5-10 min, while phagocytosis is observed in 1-3 h. The rate of test particle entrapment and stability of agglutinales clearly
depends on the larval age. The most pronounced reaction of hemocytes to foreign particles may be observed by the end of feeding
and crop emptying. The second, somewhat less expressed rise of activity occurs in mature larvae not long before the onset of
pupariation. Diapause induction is accompanied by reducing activities of both plasmatocytes and thrompocytoids. The importance
of different hemocyte types in cellular immune reaction of Calliphora vicina larvae, and coordination between plasmatocytes
and thrombocytoids are discussed.
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