The fine structure of elongate gametocytes of Leucocytozoon ziemanni (Laveran).

In an effort to establish comparative data within the genus Leucocytozoon, elongate gametocytes of L. ziemanni from naturally infected great horned owls (Bubo virginianus) were examined by electron microscopy. Micro- and macrogametocytes proved to be easily distinguishable at the electron microscopic level due to dramatic dimorphism at maturity and cytoplasmic and nuclear morphology. The parasite membrane architecture, number and type of cytoplasmic ribosomes of both micro- and macrogametocytes, presence and arrangement of osmiophilic bodies and electron dense spheres, mitochondrial morphology, endoplasmic reticulum cisternae morphology, mitochondria containing pocket infoldings of the nuclear membrane of the microgametocytes, and cytostome and food vacuole formation compare favorably with available information on L. simondi and L. smithi. Comparative variations exist only in that L. ziemanni gametocytes apparently lack compartmentalization of the cytoplasm by aligned unit membranes and parasite induced separations of the host cell nucleus as reported for L. simondi.     

Cytochemical study of the different stages in the life cycle of Toxoplasma gondii. IX. The polysaccharides and lipids in the parasites at developmental stages from the cat intestine]

Amylopectin was detected in all the stages examined. In the oval stages the minute granules of PAS-positive material were seen in the cytoplasm when examined on fresh-frozen sections. In merozoites, amylopectin was more conspicuous with maturation. The residual body of microgametocytes contain large amounts of amylopectin; no polysaccharide was visualized in microgamete bodies. Amylopectin was most abundant in macrogametocytes and zygotes. However, no peripheral position of PAS-positive "plastic granules" (wall-forming bodies), so characteristic of other coccidia and revealed by the electron microscopy for T. gondii macrogametocytes, was seen. Acid mucopolysaccharides in the macrogametocyte were detected in the central zone, leaving the periphery of the cell unstained. Very small, if any, amounts of lipids were detected in asexual stages of T. gondii. Unlike, large accumulation of lipid droplets were seen in growing macrogametocytes suggesting the involvement of lipids along with amylopectin in the metabolism of oocysts later discharged from the host body.     

Cytochemical localization of acid mucosubstances within intestinal tissue stages of Eimeria acervulina and E. necatrix

Synopsis The distribution of acid mucopolysaccharides in the intestinal tissue stages ofEimeria acervulina andE. necatrix has been investigated. The results show that acid mucopolysaccharides are present in the asexual stages of both species and in the sexual stages ofE. acervulina. It is suggested that an esterified hyaluronic acid-like molecule is present in the cytoplasm of schizonts, merozoites, microgametocytes, macrogametocytes and oocysts as well as in the plastic granules of macrogametocytes and the oocyst wall. Sulphated mucopolysaccharides of the chondroitin type occur as additional components in the cytoplasm of the above stages, as well as in large amounts in the perinuclear area of macrogametocytes and oocysts. The functional significance of acid mucopolysaccharides in the coccidial stages is discussed.     

Simple and rapid staining for detection of Entamoeba cysts and other protozoans with fluorochromes

Three fluorochromes were applied to stain various parasitic protozoans. By double staining with 4',6-diamidino-2-phenylindole and propidium iodide, differentiation of the nuclei from the cytoplasm can easily be achieved within several seconds. The chromatoid bodies in Entamoeba cysts were stained bright red. Plasmodium yoelii at all stages except late trophozoites and young gametocytes was easily identified. In the oocysts of Cryptosporidium sp., the nuclei and cytoplasm of the sporozoites fluoresced bluish white and red, respectively, whereas the residual body appeared blue or green. The third fluorochrome, Calcofluor white M2R, was suitable for detecting the cysts of Entamoeba spp. and Chilomastix mesnili.     

Light and electron microscopy on the sporulation of the oocysts of Eimeria brunetti. I. Development of the zygote and formation of the sporoblasts

The initial stages of sporulation in oocysts of Eimeria brunetti were examined in samples sporulated at 27 degrees C for 0, 12 and 24 hours. The initial zygote was found to be roughly spherical and to contain a number of polysaccharide granules which were congregated in one region of the organism. The cytoplasm also contained some strands of rough endoplasmic reticulum together with a number of mitochondria, some Golgi bodies, and some electron translucent vacuoles. The nucleus was large, with amorphous nucleoplasm and a nucleous. The cytoplasmic mass of the zygote was limited by a single unit membrane which possessed some micropores. After initiation of the sporulation, the metabolic activity of the organism appeared to increase as evidenced by the augmentation in the cytoplasm of the amounts of rough endoplasmic reticulum, number of Golgi bodies, and the appearance of polyribosomes. However, at this stage, the presence of large spherical bodies (anlagen of the refractile bodies of the sporozoites) constituted the most obvious change in the cytoplasm of the organism. After nuclear division the daughter nuclei were situated well separated in the cytoplasm and the polysaccharide granules were evenly distributed throughout the cytoplasm of the zygote. Eventually four sporoblasts were formed by invaginations of the limiting membrane. Each sporoblast was limited by a unit membrane and contained a nucleus, and the same cytoplasmic organelles as found in the zygote. The development of the sporoblast was initially accompanied by the appearance of a second limiting membrane.     

Fine Structure of Haemoproteus columbae Kruse During Macrogametogenesis and Fertilization*

When blood is withdrawn from a pigeon (Columba livia) infected with gametocytes of Haemoproteus columbae, differentiation of the gametes begins immediately. This study examines the formation of the macrogamete and its fertilization. The first visible signs of differentiation are the elongation of the nucleus along with the appearance of an intranuclear spindle and atypical centrioles. Then maturation bodies, the products of nuclear reduction, form in both erythrocytic macrogametocytes and macrogametocytes free of their host cells. Penetration of the macrogamete by the microgamete occurs rapidly. Their plasma membranes fuse, and the microgamete's nucleus, axonemes and cytoplasm enter the macrogamete. The nucleus of the microgamete expands and migrates to lie at an angle to the macrogamete nucleus. The 2 fuse across a small area. The nuclear envelope and the plasma membrane of the zygote are a mosaic of the membranes of the 2 gametes.     

Ultrastructural aspects of Fallisia effusa (Haemosporina: Garniidae) in thrombocytes of the lizard Neusticurus bicarinatus (Reptilia: Teiidae)

The fine structure of the different stages of the Fallisia effusa (Haemosporina: Garniidae), infecting the thrombocytes of the semi-aquatic Amazonian lizard Neusticurus bicarinatus (Reptilia: Teiidae) is described. Gametocytes, meronts, and merozoites of Fallisia effusa were found within a parasitophorous vacuole (PV). Multiple infections of micro- and macrogametocytes were observed. A circumferential coil of microtubules was seen in the cytoplasm of the infected host cell and this microtubule array was pronounced in cells harboring gametocytes. A deep invagination of the inner membrane complex of gametocytes may be involved in nutrition. The non-pigmented parasites underwent both merogony and gametogony in thrombocytes of the peripheral blood. No infection of the erythrocytes was observed. These observations confirm that Fallisia effusa displays characteristic features distinguishing it from other members of the Haemosporidian families, and that it has the ability to modulate microtubule assembly.     

Studies on Hepatocystis sp. in rhesus monkeys from Yunnan, China

A survey for the prevalence of Hepatocystis sp. was done on 10 rhesus monkeys (M. mulatta) from Yunnan, China. Examinations were performed on blood smears to detect erythrocytic gametocytes of the parasite, and on livers to detect merocysts. In 6 out of 10 monkeys, Hepatocystis sp. infection was confirmed. The gametocytes took about 6 days to reach maturity. The fully grown macrogametocytes were about 8 microns in diameter. The cytoplasm was stained pale lilac and the nucleus consisted of dense chromatin dots lying in an unstained zone. The microgametocytes had cytoplasm dyed a biscuit color and large nuclei dyed pink. In the pathological section of livers, the merocyst measured about 3 mm in diameter and had a smooth outline without any projecting limb. The characteristics of this protozoan species were very similar to those of H. taiwanensis. However, more work should be done to clarify the relationship between this species and H. taiwanensis.     

Ultrastructural Observations on the Gametocytic Stages of the Coccidium Tyzzeria chalcides Probert, Roberts & Wilson, 1988 from the Ocellated Skink Chalcides ocellatus

Gametogenesis of Tyzzeria chalcides Probert, Roberts & Wilson, 1988, from the ocellated skink, Chalcides ocellatus , occurs within the epithelium of the gali bladder. Transmission electron microscopy reveals that macrogamonts contain 2 types of wall-forming bodies. Type I bodies are large densely stained structures associated with rough endoplasmic reticulum and the Golgi apparatus. They appear to be formed within the Golgi itself. Type II bodies are less densely stained, smaller and appear to form directly from the rough endoplasmic reticulum. Canaliculi are associated with Type I wall-forming bodies and probably function to transport the wall-forming bodies to the pellicle. Micropores occur in the pellicie and large amylopectin granules, lipid globules and dense bodies are found within the cytoplasm of the macrogamont. Mature microgamonts contain in excess of 20 microgametes, each of which has 2 flagella and an associated mitochondrion. Both types of gamont are found within a parasitophorous vacuole, in the host cell, which is filled with vesicular material on which the gamonts probably feed.     

The Fine Structure of the Macrogametocytes of Adelina tribolii Bhatia, 1937 (Eucoccidia, Telosporea) from the Fat Body of the Beetle Tribolium castaneum Hbst.

SYNOPSIS. Macrogametocytes of the coccidium Adelina tribolii Bhatia, 1937 are described from the time when they settle in the fat body of the host and form periparasitic vacuoles around them to the stage of microgametocyte occurrence and the beginning of syzygy formation.
The macrogametocyte is surrounded by a 2-layered pellicle 50 mμ thick. Its continuity is interrupted by one or several micropores 40 mμ across and 86 mμ deep.
The cytoplasm of the parasite contains numerous vesicles and lamellae of rough and smooth endoplasmic reticulum. Mitochondria of various sizes have short tubules. The macrogametocyte contains a variable number of dark bodies 1.4-2.4 μ in diameter. It also contains several vacuoles up to 1.2 μ which are covered with a 3-layered membrane and enclose a granular material.
In old macrogametocytes in syzygy multivesicular bodies develop which measure up to 2.4 by 1.6 μ. Several smaller vacuoles containing granular material are also a constituent of the electrondense basic substance of these corpuscles.
Paraglycogen granules 1.4 by 0.9 A occur in old macrogametocytes and are situated inside the vacuoles which are not bordered by a membrane. The numbers and size of these granules increase with the age of the parasite. The Golgi complex lies close to the nucleus.
The nucleus, 6-8.5 μ in diameter, is in the center of the macrogametocyte and contains a large eccentric nucleolus. The nuclear membrane is 2-layered and has many pores.     

Leucocytozoon in the Avian Order Columbiformes, with a Description of L. marchouxi Mathis and Leǵer 1910 from the Mourning Dove

Leucocytozoon marchouxi is described from the mourning dove, Zenaidura macroura carolinensis in Illinois. The macrogametocytes are rounded or elliptical, measuring 7 to 11 by 8 to 15 microns (mean, 9 by 12 microns), and stain dark blue with Giemsa stain. The microgametocytes are often distorted or ruptured by the smearing process, but if not badly injured measure 5 to 11 by 8 to 15 microns, (mean, 8 by 11 microns). They stain pale blue with Giemsa stain. Host cell cytoplasm is rarely seen surrounding the microgametocytes, but was found in 26% of cells parasitized by the macrogametocytes. When present it forms a narrow border around part or all of the parasite's periphery, and is not drawn out to form elongate "horns."
The parasite was found in ten birds, of which five were adults, one was a juvenile, and four were nestlings. The infections were relatively light in the adults. The youngest bird in which the protozoon was found was 14 days old.
The literature on Leucocytozoon in the avian order Columbiformes is reviewed. All forms with rounded gametocytes so far reported are considered to be L. marchouxi Mathis and Leger, 1910, of which L. turtur Covaleda Ortega and Gallego Berenguer, 1946, is considered a synonym.     

Sporogonic development of Leucocytozoon smithi.

The sporogonic development of Leucocytozoon smithi in its black fly vector was studied by light and electron microscopy and was compared with that of other haemosporidians. Within 18 to 24 h after ingestion of gametocytes by black flies, ookinetes passing through the midgut epithelium were observed. Intracellular migration of ookinetes resulted in the apparent disruption and degeneration of host cells. Intercellular migration also occurred as was evidenced by the presence of ookinetes between midgut cells. Transformation of ookinete to spherical oocyst occurred extracellularly in three different sites. Although most oocysts were found between the host cell basal membrane and the basal lamina, large numbers also were found attached to the external surface of the basal lamina, projecting into the hemocoel. Ectopic development of oocysts in the midgut epithelium between cells was observed much less frequently than development on the basal side of the midgut. The oocyst wall of dense granules, believed to be of parasite origin, was distinguishable from the basal lamina of the host's midgut epithelium. As in other Leucocytozoidae, the cytoplasm of the oocyst differentiated into a single sporoblastoid from which 30-50 sporozoites were formed. Beginning on the third day post infection, elongation of segregated dense sporoblastoid material associated with pellicle thickening led to the formation of the finger-like sporozoite buds which projected into the oocyst cavity. Sporozoites within mature oocysts and salivary glands were structurally similar to sporozoites as described for other haemosporidians.     

Sporogonic Development of Leucocytozoon smithi

The sporogonic development of Leucocytozoon smithi in its black fly vector was studied by light and electron microscopy and was compared with that of other haemosporidians. Within 18 to 24 h after ingestion of gametocytes by black flies, ookinetes passing through the midgut epithelium were observed. Intracellular migration of ookinetes resulted in the apparent disruption and degeneration of host cells. Intercellular migration also occurred as was evidenced by the presence of ookinetes between midgut cells. Transformation of ookinete to spherical oocyst occurred extracellularly in three different sites. Although most oocysts were found between the host cell basal membrane and the basal lamina, large numbers also were found attached to the external surface of the basal lamina, projecting into the hemocoel. Ectopic development of oocysts in the midgut epithelium between cells was observed much less frequently than development on the basal side of the midgut. The oocyst wall of dense granules, believed to be of parasite origin, was distinguishable from the basal lamina of the host's midgut epithelium. As in other Leucocytozoidae, the cytoplasm of the oocyst differentiated into a single sporoblastoid from which 30–50 sporozoites were formed. Beginning on the third day post infection, elongation of segregated dense sporoblastoid material associated with pellicle thickening led to the formation of the finger-like sporozoite buds which projected into the oocyst cavity. Sporozoites within mature oocysts and salivary glands were structurally similar to sporozoites as described for other haemosporidians.     

约氏疟原虫配子体形成的形态学特征

应用六氰酸铁钾和锇酸双染色法的透射电镜技术,对红内期疟原虫配子体形成过程中的形态生物学特征进行识别。结果表明,配子体是一渐进发育的单核、惰性(团块样、虫体不活跃)虫体,其核旁有一个由扁平囊和泡状小体极性排列组成的细胞器——高尔基体(Golgi complex),虫体被膜下有嗜锇小体。其雌性配子体的结构特点是核质较致密、内质网丰富和被膜下嗜锇小体多;而雄性配子体却是核质较疏松、线粒体发达、内织网和嗜锇小体少。结论是红内期疟原虫配子体形成与裂体增殖过程中形态结构的明显差别,雌雄配子体在结构与发育上明显的差异,都具有特定的生物学与生态学意义。     

Structure, Cytochemistry, and Locomotion of Haemogregarina sp. from Rana berlandieri

Intra- and extracellular gametocytes of Haemogregarina sp. from Rana berlandieri were studied by light and electron microscopy. Locomotion in free gametocytes appears to be related to series of horizontal “peristaltic” waves of constriction, passing from anterior to posterior along the body. Intracellular gametocytes lie within a vacuole in the erythrocyte cytoplasm. The pellicle of the parasite consists of a trilaminar plasmalemma and an inner electron dense layer, beneath which lies a ring of 80 microtubules. The inner dense layer becomes thickened and modified in the apical region, to form a cap-like structure. The gametocytes contain a prominent nucleus, several mitochondria, and many granular inclusions. One type of inclusion consists of elliptical, electron-dense, profeinaceous bodies scattered throughout the cytoplasm, while other inclusions are larger and electron-opaque, polysaccharide in nature, and occur predominantly in the pre- and post-nuclear regions. In the electron microscope, pronounced pellicular folds were observed in longitudinally sectioned extracellular gametocytes. These folds are thought to represent the waves of constriction seen in motile specimens by light microscopy. The mechanism of movement of the parasite is discussed and compared with that in haemosporidian ookinetes, as well as in gregarines.     

Observations on Eimeria raillieti in the "Slow-worm", Anguis fragilis (Reptilia, Anguidae)

SYNOPSIS. The oocysts, sporulation process, and endogenous stages of Eimeria raillieti (Léger, 1899) Galli-Valerio, 1930 from the slow-worm, Anguis fragilis , in England are described. The oocysts average 18 × 15 μ. Schizonts, microgametocytes and macrogametocytes were found in the ileum, and macro-gametocytes alone in the duodenum.     

Structure of taste buds in foliate papillae of the rhesus monkey, Macaca mulatta

Taste buds in foliate papillae of the rhesus monkey were examined by electron microscopy. Three distinct cell types were identified. Type I cells were narrow elongated cells containing an oval nucleus, bundles of intermediate filaments, several Golgi bodies, and characteristic apical membrane-bounded dense granules. These cells exhibited morphological variations: some had a moderately dense cytoplasm, perinuclear free ribosomes, and flattened sacs of rough endoplasmic reticulum; others had a more lucent cytoplasm, dilated irregular rough endoplasmic reticulum, lysosome-like dense bodies, and lipid droplets. Type II cells typically contained a spherical, pale nucleus, a prominent nucleolus, supranuclear and infranuclear Golgi bodies, mitochondria with tubular cristae, and one or two centrioles. This cell type, too, showed some variation in the relative amounts of ribosomes and smooth endoplasmic reticulum, which varied inversely with each other. Type III cells were characterized by a clear apical cytoplasm essentially devoid of ribosomes and containing microtubules. In a few type III cells, the peri- and infranuclear regions contained many ribosomes and some rough endoplasmic reticulum. In most Type III cells, there were large numbers of dense and clear vesicles in the peri- and infranuclear regions; some of the vesicles were grouped in synapse-like arrangements with adjacent nerves. The morphological variations exhibited by all three cell types could be accounted for by age differences in each of the cells. This would be consistent with the notion that cell renewal occurs in each of the three cell populations.     

Early Stages in the Differentiation of Gametocytes of Haemoproteus columbae Kruse*

SYNOPSIS The sexes of mature gametocytes of Haemoproteus columbae Kruse circulating in the blood of the domestic pigeon can be identified in the electron microscope by the same criteria that distinguish them in the light microscope. The microgametocyte has a large nucleus and pigment granules restricted to the 2 extremities of its halter-shaped cells. The macrogametocyte has dense granular cytoplasm with scattered pigment granules and a small central nucleus. The sex of young gametocytes cannot yet be recognized. When blood containing mature gametocytes is cooled outside the body of the host visible signs of gametogenesis appear within 30 seconds. The earliest signs are increasing electron lucidity of the cytoplasm and separation of the outer membrane from the body of the parasite. The membrane may form vesicles or whorls or lie free in the erythrocyte's cytoplasm. The middle membrane of the parasite becomes the plasma membrane. Axonemes and microtubules appear in the cytoplasm and nucleoplasm of the microgametocyte. The macrogametocyte lags slightly behind the microgametocyte in development. With the first signs of differentiation, the host cell cytoplasm begins to disappear. The fate of the outer membrane and the erythrocyte's cytoplasm suggests the release of a lytic substance by the parasite.     

THE ULTRASTRUCTURE AND HISTOCHEMISTRY OF A NEMATODE-INDUCED GIANT CELL

The development of giant cells induced by the nematode Meloidogyne in tomato roots has been followed under controlled growth conditions and the ultrastructure and histochemistry of these structures have been examined. Entry of the nematode larvae into the roots took place within 24 hours; giant cell formation started on the 4th day and involved breakdown of the cell walls accompanied by thickening of a surrounding giant cell wall and an increase in density and area of the cytoplasm. The nuclei increased in number by simultaneous mitosis throughout a single giant cell. The peak of cytoplasmic density was reached after moulting and during egg production. The rate of protein synthesis in the giant cell is correlated with the rate of growth of the nematode. The giant cell wall is a thick, irregularly surfaced structure which contains all the normal polysaccharide components of a cell wall. The cytoplasm is rich in protein and RNA and contains mitochondria, proplastids, Golgi bodies, and a dense endoplasmic reticulum. The nuclei are large and irregular in shape and contain large nucleoli and a number of Feulgen-positive bodies scattered irregularly along the nuclear envelope. The nucleolus contains RNA and fat as well as Feulgen-positive granules which are revealed after treatment with ribonuclease. It consists of a dense outer cortex surrounding a much lighter central core and is connected at times with the Feulgen-positive bodies in the nucleus. Speculation is provided on the role of these bodies in cytoplasmic protein synthesis.     

Ultrastructural pathology of the epidermis of molting elaterid larvae (Coleoptera) with a fungus and a bacterium in the ecdysial space

Toxins produced by the fungus Metarrhizium anisopliae and the bacterium Pseudomonas aeruginosa in the ecdysial space of a molting wireworm are absorbed through the thin new cuticle and ultrastructurally change the epidermal cells into two distinct types. One is a rounded, degenerative type characterized by a “light” cytoplasm with vesiculated rough endoplasmic reticulum, rounded mitochondria with degenerated cristae, little ground plasm, and a rounded nucleus with little nucleoplasm and large globules of condensed chromatin from which chromatin fibrils separate in loose folds or granulelike tight folds. The other type has very irregular outlines and is characterized by a “dark” cytoplasm with abundant, whorled laminae of rough endoplasmic reticulum and abundant free ribosomes in a dense ground plasm, large rounded clear vacuoles, and apparently normal mitochondria and nuclei. The fungal toxins are believed to be primarily responsible for the formation of the light cells, and the bacterial toxins, for the separation of the chromatin into fibrils in the light cells, the fusion of their nuclei into large nuclear bodies, and the changes in the cytoplasmic contents of the dark cells. The dark cells, although abnormal, appear to retain a limited secretory activity.