The Morphology and Behavior of Living Exoerythrocytic Stages of Plasmodium gallinaceum and P. fallax and Their Host Cells

Abstract

The morphology and behavior of living exoerythrocytic stages of Plasmodium galllnaceum and -P. fallax were studied by the use of tissue cultures, phase contrast microscopy, and time-lapse cinephotomicrography. The morphology of exoerythrocytic stages of these two species was essentially that previously observed in fixed, stained material, with the following exceptions: (1) the presence of a filament on one end of the merozoite, (2) the absence of clefts in the cytoplasm of the large schizonts, and (3) the absence of a vacuole-like space around the parasite.The following behavior was observed either directly or in time-lapse sequences: (1) emergence of merozoites from mature schizonts, (2) progressive motility of free merozoites, (3) entry of merozoites, both actively and passively, into host cells, (4) nuclear division in the parasite, (5) the various stages of schizogony, including final production of merozoites, (6) massive infection of host cells, and (7) phagocytosis of merozoites and attempted phagocytosis of mature schizonts by macrophages.Exoerythrocytic stages of P. fallax differed from those of P. gallinaceum in that the merozoites of the former were (1) somewhat more curved in shape and (2) present in fewer numbers in mature schizonts.The use of tissue culture, phase contrast microscopy, and time-lapse cinephotomicrography promises to solve many of the remaining problems concerning exoerythrocytic stages of malarial parasites and their interrelationships with host cells.

Structure of a Nonpathogenic Histomonad from the Cecum of Galliform Birds and Revision of the Trichomonad Family Monocercomonadidae Kirby*

“…The chickens were killed periodically, and their cecal contents used to make temporary preparations of living organisms to be studied with the aid of phase contrast and of permanent mounts. Small samples of infected cecal material were inoculated into chick liver cell cultures prepared on coverglasses in Leighton tubes according to the method described by Honigberg et al (25), after Huff et al (28). Large amounts of penicilin (2000 un/ml) and of streptomycin (2000 pg/ml) were added to the cell culture medium before exposing the cultures to the cecal contents.…”

Cell Biology

“…T h e m a t u r e merozoite, w h i c h frequently has b o t h rhoptries a n d micronemes, is highly motile (Huff et al, 1960), a n d m a y therefore contribute to t h e r u p t u r e of m a t u r e schizonts. As merozoites of tissue schizonts are shed into sinusoids of the liver, they quickly i n v a d e erythrocytes.…”

The Feeding Mechanism of Avian Malarial Parasites

“…THE JOURNAL OF CELL BIOLOGY • VOLUME ~8, 1966 know from the cinematographic studies of Huff et al (9), that once an exoerythrocytic merozoite enters a new cell it rounds up and initiates the exoerythrocytic cycle, and that no example of extrusion of the cell contents has been observed. Furthermore, in an extension of the light microscopic studies of Huff et al, we have been able with the aid of the electron microscope to confirm their findings with examples of merozoites in various stages of rounding up.…”