The morphology and behavior of living exoerythrocytic stages of Plasmodium gallinaceum and P. fallax and their host cells.

Clay G Huff,Dinniemaud V Jensen,Alan C Pipkin,A B Weathersby

doi:10.1083/jcb.7.1.93

Clay G Huff, Dinniemaud V Jensen + Show 2 more

Open Access

https://doi.org/10.1083/jcb.7.1.93

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Abstract

The morphology and behavior of living exoerythrocytic stages of Plasmodium gallinaceum 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.

Highlights

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
In agreement with the previous finding on fixed material we found that the number of merozoites in the mature schizont was smaller in P. fallax than in P. gallinaceum
Comparison of Fixed and Stained Material with Living Parasites Seen with Phase Contrast Microscopy.--The appearance of exoerythrocytic stages by positive phase contrast microscopy resembled very closely their appearance in wet-fixed material stained with Maximow's hematoxylin-eosin-azur method, except for the colors in the latter

Summary

INTRODUCTION

The cell-parasite complex offers the Living exoerythrocytic stages of malarial parasites offer certain advantages for cytological study not offered by other cells. These stages are known to be obligate parasites of several different types advantage that the interaction of two ceils can be observed. MALARIAL EXOERYTHROCYTIC STAGES describe the morphology of the living exoerythrocytic stages of these two species, (2) to compare these observations with published descriptions of fixed and stained material (see Huff and Coulston, 1944), (3) to describe their behavior based on visual observations and upon time-lapse moving pictures, and (4) to describe some of the interrelations of the exoerythrocytic stages and their host cells

Materials and Methods

Findings

DISCUSSION