Sieve-element plastids ofTriticum andAegilops (Poaceae)

Fourteen taxa of the Triticum-Aegilops group have been investigated for their sieve-element plastids. At maturity they contain dense and thin crystalloid inclusions and are classified into the PIIc' plastid type; onlyAe. comosa var.biaristata lacked the thin crystalloids and thus conforms to the PII c type. The proteinaceous nature of the crystalloids was demonstrated by application of proteolytic enzymes. Ultrastructural evidence suggests that both kinds of crystalloid inclusions are involved in the sealing of sieve-plate pores of injured sieve tubes. Measurements and calculations of the spacings and angles carried out on crystalloid prints permitted the construction of a two- and three-dimensional pattern forT. aestivum thin crystalloids.     

Ultrastructure of crystalloid inclusions in the dog and rat epididymis

Fine structural studies of the epididymis of mature mongrel dogs and of Sprague-Dawley rats were undertaken in conjunction with research dealing with the effects of vasectomy upon this organ. This paper reports the observation of crystalloid and lamellar inclusions present in these species following fixation of the epididymis in 5 % glutaraldehyde, post-fixation in osmium, and routine processing for electron microscopy. In the dog, crystalloid inclusions were observed within the cauda epididymidis of unoperated and vasectomized animals. They were found within the apical cytoplasm of principal cells in association with the Golgi apparatus and endoplasmic reticulum, and in some instances, in close proximity to the nucleus. These crystalloids exhibited a 12 nm periodicity and often measured over 3 μm in length. In the rat, two types of inclusions were found, one within mitochondria of clear cells from unoperated animals and another within membrane-bound bodies of principal cells from the caput epididymidis of unoperated and vasectomized animals. The mitochondria which contained inclusions were basally located and were observed in stacks of up to eight elongate mitochondria each. The mitochondrial inclusions exhibited a complex lamellar structure with an approximate periodicity of 36 nm. In contrast, the crystalloid inclusions found within principal cells were sequestered within supranuclear cytoplasmic bodies which increased in number with age. Such crystalloids exhibited a linear periodicity of 11–13.5 nm, but the precise lattice structure remains to be determined. Although certain aspects of the morphology of these bodies suggests a relationship to microbodies, we have been unable to demonstrate catalase activity within them. At present, neither the origin of crystalloid structures described, nor their relationship to epididymal physiology is clear.     

Gametocyte Maturation,Exflagellation and Fertilization in Parahaemoproteus (=Haemoproteus) velans (Coatney & Roudabush) (Haemosporidia: Haemoproteidae): an Ultrastructural Study*

SYNOPSIS. The structural changes in macro and microgametocytes of Parahaemoproteus velans following removal of infected blood from the avian host were studied in the light and electron microscope. Gametocytes of both sexes round up and soon escape from their host cells. Shortly thereafter they assume a dumbbell shape. The microgametocyte undergoes exflagellation forming 8 slender microgametes. During fertilization the entire microgamete appears to enter the female. The most striking ultrastructural change in the formation of the macrogamete is the condensation and enclosure by a membrane of abundant amophorus dense material seen in the cytoplasm of the immature gametocyte. Maturation of the microgametocyte begins prior to its escape from the host cell. Axonemes are present in the cytoplasm and nuclear reorganization occurs while the parasite is intracellular. Bundles of microtubules associated with condensed chromatin are found in the peripheral cytoplasm of maturing forms and apparently participate in the formation of small compact microgamete nuclei. Each of these filiform structures consists of a dense, centrally located nucleus and a single axoneme lying in flocculent cytoplasm. The nucleus and axoneme of the microgamete are seen free in the cytoplasm of a fertilized macrogamete.     

Experimental Studies of the Life Cycle of Leucocytozoon simondi in Ducks in Norway*

SYNOPSIS. Pekin ducks were infected naturally and experimentally. The life cycle of Leucocytozoon simondi was followed in the ducks and the vector, a new species of Simulium, close to Simulium dogieli. The prepatent period in the ducks was 4–5 days and developing megaloschizonts appeared in 6–7 days. Schizonts were found in liver, spleen, brain, and kidney. In the kidneys they were located in the glomeruli. Sporogony in some individuals was completed in 7 days at 13–14 C, other individuals developed more slowly, as ookinetes were found in flies 8 days after feeding. The rapid asexual cycle combined with a sporogonic cycle, in which some ookinetes develop rapidly and others more slowly, favors the maintenance of the parasite in an environment with relatively low daily temperatures. This and the size of the megaloschizonts indicate differences between this strain of the parasite and the one occurring in North America.     

Aspects of the sporogonic development of Leucocytozoon tawaki of the Fiordland crested penguin in its primary vector, Austrosimulium ungulatum: an ultrastructural study.

Early oocysts of Leucocytozoon tawaki Fallis, Bisset and Allison were located between the basal lamina and the midgut epithelium of the vector, Austrosimulium ungulatum. The spherical oocysts were surrounded by an amorphous, electron-dense wall and contained a large, central core of closely spaced dense particles, the crystalloid inclusion. Around the latter were many concentrically arranged cisternae of granular endoplasmic reticulum. A few large, poorly defined nuclei, some of which contained spindle apparatus, were seen. Sporozoite formation occurred around the peripheral cytoplasm of maturing oocysts. The sporozoite pellicle was subtended by 30 microtubules which appeared to originate from the most posterior of 3 dense, polar rings. Each forming sporozoite contained a central nucleus, mitochondrion, and a crystalloid inclusion both anterior and posterior to the nucleus. The nature and significance of the crystalloid in Leucocytozoan species and other apicomplexans is discussed with special reference to similar viruslike inclusions in the sporogonic stages of certain species of Plasmodium.     

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.     

Occurrence,composition, and structure of microbody crystalloids in charophycean gametangial sheath cells

Summary An ultrastructural study was made of the cellular sheaths surrounding the sexual organs of five species of algae in the three genera ofCharophyceae: Nitella flexilis, N. mirabilis, Chara brattnii, Tolypella boldii andT. intricata. Microbodies similar in appearance, with crystalline nucleoids, were present in the sheath cells of all five species. The microbodies resembled in size and topographical associations those of other green algae. The hexagonal-shaped crystalloids consisted of parallel arrays of fine tubules of about 15 nm in diameter arranged parallel to the long axis of the crystalloid. In cross sections of the crystalloid, the close packing of the tubules showed hexagonal arrays. The intertubular distance is about 7 nm. At higher magnification there is a suggestion that the walls of these tubules are themselves constructed of smaller tubules. Further electron microscopic observations of diaminobenzidine (DAB)-treated preparations revealed pronounced deposition of reaction product in the microbodies, particularly on the crystalloids. The reaction was completely blocked by the catalase inhibitor, aminotriazole. These results strongly suggest that catalase is involved in this reaction and that catalase is located in the crystalloids.     

A Comparative Study of Gametocyte Ultrastructure in Avian Haemosporidia*

The fine structure of gametocytes of 3 avian haemosporidian parasites Plasmodium gallinaceum, Haemoproteus columbae, and Leucocytozoon simondi has been studied and compared by electron microscopy. The gametocytes of all 3 species are bounded by a 3-layered limiting membrane system, possess a cytostome during some portion of their residence within host cells, and their sex can be distinguished by both nuclear and cytoplasmic characteristics. L. simondi differs most significantly from P. gallinaceum and H. columbae in possessing large intranuclear granules, mitochondria associated with pocket infoldings of the nuclear envelope near the atypical centriole complex and compartmentalization of the cytoplasm by segments of closely aligned unit membranes. Further, the cytostome of L. simondi does not appear to be a persistent structure as in the other 2 species and pigment is not present within food vacuoles. L. simondi also is capable of infecting a wider variety of host cells and within leukocytes produces striations of the host nucleus and an apparent spiral banding of the host cell surface. The comparison of P. gallinaceum, H. columbae, and L. simondi gametocytes by electron microscopy leads to the conclusion that Plasmodium and Haemoproteus are more closely related to each other than either of them is on Leucocytozoon. The terminology used to describe certain organelles within the gametocyte's cytoplasm has been reexamined and the relationship of the nucleolus to parasite maturation also is described.     

Ultrastructural study of crystalloids in Sertoli cells of the normal,intersex and experimental cryptorchid swine

Spindle- or needle-shaped crystalloids are observed in Sertoli cells of the intersex and experimental cryptorchid swine in the light and electron microscopes. Small crystalloids are also observed in Sertoli cells of the normal swine only by electron microscopy. These crystalloids consist of fine filaments. The filaments are about 5 nm in diameter and arranged parallel to the long axis of the drystalloid. In cross sections of the crystalloid, the close backing of the filaments shows hexagonal arrays. The interfilamentous distance is about 5 nm. In all animals, bundles of short filaments, which are 5nm in diameter, are observed in the basal part of the Sertoli cells. Ultrastructural similarities among the crystalloids, the bundles of fine filaments, and the filamentous layer in the junctional specialization of the Sertoli cell are shown. These morphological similarities suggest that the crystalloids are formed by the aggregation of the bundles in the Sertoli cells of azoospermic testes.     

Ultrastructural and cytochemical examination of the nuclear crystalloid inclusions of Olea europaea L. mesophyll cells

Summary The nuclei of mesophyll cells of olive trees contain numerous sizeable crystalloid inclusions. Cytochemical examination using epoxy resin-embedded, semithin-sectioned tissue indicated the presence of proteins and oligoor polysaccharides in these inclusions. Their electron microscopical analysis revealed a crystalline substructure consisting of intersected subunits of high order. The spacing of the lattice fibrils and the angles of intersection were determined and used to establish a model of the unit cell of crystallization. It is suggested that the nuclear crystalloids of olive trees consist of glycoprotein molecules. They differ from the intranuclear crystalloids observed in other species predominantly in the high density of their subunit arrangement.     

Fine structural and immunohistochemical localization of cardiac hormones (ANP) in the right atrium and hypothalamus of the white rat

Atrial natriuretic peptide (ANP) is a polypeptide hormone secreted primarily by atrial myoendocrine cells. It has diuretic, natriuretic and vasorelaxant effects. ANP has been characterized by non-morphological methods in a number of extra-atrial tissues, particularly the hypothalamus, but little is known of the immunohistochemistry of hypothalamic ANP cells in comparison to atrial ones. Although the presence of ANP-producing cells has previously been confirmed in the right atrium of the rat and other vertebrate species, to our knowledge, this is the first study to demonstrate the presence of these cells in the hypothalamus using a purely morphological method such as electron microscopy. The fine structural and immunohistochemical characteristics of right atrial and hypothalamic ANP positive cells were investigated using immunogold labeling with goat anti-alpha-human ANP (1-28) as primary antibody. Atrial ANP cells were characterized by the presence of membrane-bound electrondense spherical or oval granules with a diameter of about 250 nm. The opaque content of the granules is separated from the limiting membrane by a thin electron translucent band about 20 nm wide. Electron dense crystalloid inclusions were evident within the granule matrix of some atrial ANP granules. Hypothalamic ANP granules were membrane-bound larger in diameter (320 nm), and less electron dense, and lacked crystalloid inclusions. Statistical analyses revealed a significant larger diameter and a significant smaller number of hypothalamic ANP granules compared to atrial ones. The significantly greater number of atrial ANP positive granules suggests a greater volume capacity for the atrial ANP positive granules as compared to the hypothalamic ones. This may indicate that ANP is secreted primarily from the right atrium and to a lesser extent from the hypothalamus; and that both atrial and hypothalamic ANP are closely related in chemical nature and immunohistochemical characteristics. This supports the suggestion that ANP may play the dual role of peripheral hormone and a neurotransmitter or neuromediator.     

Ultrastructural investigation on a strain of a cytoplasmic-polyhedrosis virus with nuclear inclusions

A strain of a cytoplasmic-polyhedrosis virus causes the formation of crystalline inclusions almost entirely in the nucleus, and only rarely in the cytoplasm, of the midgut epithelial cells of the silkworm Bombyx mori. It also differs from the typical strain in causing the hypertrophy of the nucleoli and the formation of dense reticulum and spherical bodies in the nucleus. The virus particles and the virogenic stromata of the new strain resemble those of the typical strain. The cytoplasmic inclusions contain virus particles, while the nuclear inclusions do not. When the infected larvae are kept at 30°C for 15 hr or at 35°C for 3–15 hr, the nuclear inclusions break up into particles of 70–250 nm in diameter. The particles are dispersed in the cells but not present in the spaces previously occupied by the decomposed inclusions.     

Cell types of the endocrine pancreas in the shark Scyliorhinus stellaris as revealed by correlative light and electron microscopy

Summary In the pancreas of Scyliorhinus stellaris large islets are usually found around small ducts, the inner surface of which is covered by elongated epithelial cells; thus the endocrine cells are never exposed directly to the lumen of the duct. Sometimes, single islet cells or small groups of endocrine elements are also incorporated into acini. Using correlative light and electron microscopy, eight islet cell types were identified:Only B-cells (type I) display a positive reaction with pseudoisocyanin and aldehyde-fuchsin staining. This cell type contains numerous small secretory granules (Ø280 nm). Type II- and III-cells possess large granules stainable with orange G and azocarmine and show strong luminescence with dark-field microscopy. Type II-cells have spherical (Ø700 nm), type III-cells spherical to elongated granules (Ø450 × 750 nm). Type II-cells are possibly analogous to A-cells, while type III-cells resemble mammalian enterochromaffin cells. Type IV- cells contain granules (Ø540 nm) of high electron density showing a positive reaction to the Hellman-Hellerström silver impregnation and a negative reaction to Grimelius' silver impregnation; they are most probably analogous to D-cells of other species. Type VI-cells exhibit smaller granules (Ø250 × 500 nm), oval to elongated in shape. Type VI-cells contain small spherical granules (Ø310 nm). Type VII-cells possess two kinds of large granules interspersed in the cytoplasm; one type is spherical and electron dense (Ø650 nm), the other spherical and less electron dense (Ø900 nm). Type VIII-cells have small granules curved in shape and show moderate electron density (Ø100 nm). Grimelius-positive secretory granules were not only found in cell types II and III, but also in types V, VI, and VII. B-cells (type I) and the cell types II to IV were the most frequent cells; types V to VII occurred occasionally, whereas type VIII-cells were very rare.This work was supported by a fellowship from the Ministry of Education of Japan and the Deutsche Forschungsgemeinschaft, Bonn-Bad Godesberg (La 229/8)     

Electron Microscopy of an Isometric Caulimo-Like Virus from Sweet Potato (Ipomoea batatas)

A newly recognised virus with isometric particles 50 nm in diameter was detected in Ipomoea batatas (sweet potato) by graft-transmission to I. setosa. Virus particles and intracellular inclusions, although not seen in infected I. batatus, were found in the cytoplasm of most cell types of I. setosa. The caulimo-like particles were most abundant with vesicles immediately adjacent to inclusions. The ovoid or spherical inclusions, which differ markedly from those of caulimovi, ruses, have a large central lacuna and usually several smaller peripheral lacunae. Infected vascular parenchyma cells sometimes protrude into, and occasionally completely occlude, adjacent xylem vessels, observations possibly explaining the sudden wilting and premature senescence of infected leaves.     

Electron microscopic study on the innervation of the pancreas of the domestic fowl

Summary The innervation of the pancreas of the domestic fowl was studied electron microscopically. The extrapancreatic nerve is composed mostly of unmyelinated nerve fibers with a smaller component of myelinated nerve fibers. The latter are not found in the parenchyma. The pancreas contains ganglion cells in the interlobular connective tissue. The unmyelinated nerve fibers branch off along blood vessels. Their synaptic terminals contact with the exocrine and endocrine tissues. The synaptic terminals can be divided into four types based on a combination of three kinds of synaptic vesicles. Type I synaptic terminals contain only small clear vesicles about 600 Å in diameter. Type II terminals are characterized by small clear and large dense core vesicles 1,000 Å in diameter. Type III terminals contain small clear vesicles and small dense core vesicles 500 Å in diameter. Type IV terminals are characterized by small and large dense core vesicles. The exocrine tissue receives a richer nervous supply than the endocrine tissue. Type II and IV terminals are distributed in the acinus, and they contact A and D cells of the islets. B cells and pancreatic ducts are supplied mainly by Type II terminals, the blood vessels by Type IV terminals.This work was supported by a scientific research grant (No. 144017) and (No. 136031) from the Ministry of Education of Japan to Prof. M. Yasuda     

Cytopathology of Plgeonpea sterility mosaic virus in pigeonpea and Nicotiana benthamiana: similarities with those of eriophyid mite-borne agents of undefined aetiology

Pigeonpea sterility mosaic virus (PPSMV) is transmitted by the eriophyid mite, Aceria cajani, and is very closely associated with sterility mosaic disease (SMD) of pigeonpea (Cajanus cajah) in the Indian subcontinent. Antiserum produced to purified PPSMV preparations detected a virus‐specific 32 kDa protein in sap of SMD‐affected pigeonpea plants by ELISA and Western blotting. PPSMV was transmitted mechanically in sap of SMD‐affected pigeonpea leaves to Nicotiana benthamiana. Ultrastructural studies of symptom‐bearing leaves of two pigeonpea cultivars, (ICP8863 and ICP2376) and N. benthamiana infected with PPSMV, detected quasi‐spherical, membrane bound bodies (MBBs) of c. 100–150 nm and amorphous electron‐dense material (EDM). These structures were distributed singly or in groups, in the cytoplasm of all cells, except those in conductive tissues. Fibrous inclusions (FIs), composed of randomly dispersed fibrils with electron lucent areas, were present in the cytoplasm of palisade cells and rarely in mesophyll cells of the two pigeonpea cultivars but were not detected in infected TV. benthamiana plants. In the PPSMV‐infected pigeonpea cultivars and TV. benthamiana, immuno‐gold labelling, using antiserum to PPSMV, specifically labelled the MBBs and associated EDM, but not the FIs. The MBBs and associated inclusions are similar in appearance to those reported for plants infected with the eriophyid mite‐transmitted High Plains virus and the agents of unidentified aetiology associated with rose rosette, fig mosaic, thistle mosaic, wheat spot chlorosis and yellow ringspot of budwood. The nature of these different inclusions is discussed.     

Freeze fracture studies of reaction centers from Rhodospirillum rubrum in chromatophores and liposomes

In freeze-fractures of chromatophores of Rhodospirillum rubrum the reaction centers are seen as hexagonal arranged particles of 13 nm diameter with a density of around 5,500 particles per m². Similar regions on the cytoplasmic membrane suggest that these parts are the prospective invagination sites.Isolated reaction centers are easily incorporated into liposomes. In freeze fractures of liposomes particles similar in shape and size, although less dense as in chromatophores are observed. In negative staining much smaller units of only 5 nm in diameter are found indicating that reaction centers occur in the membrane as tri- or tetramers. There is a strong correlation between particle density in chromatophores and titratable reaction centers remaining in these membranes after extraction of reaction centers by detergents; both values are in good agreement with the yield of reaction centers at a given detergent concentration.Abbreviations LDAO Lauryldimethylamine oxide - PF protoplasmic fracture face - EF exoplasmic fracture face     

Fine Structure of Haemoproteus columbae Kruse During Differentiation of the Ookinete*

Ookinete differentiation begins in vitro～1 hr after blood infected with mature gametocytes of Haemoproteus columbae is withdrawn from a pigeon. In the undifferentiated zygote, dense material accumulates at the point under the plasma membrane. The conoid and conoidal rings condense from this material. The nucleus is drawn out to a point with the intranuclear spindle (INS) at the peak. Atypical centrioles lie under the forming conoid in the cytoplasm next to the INS. Fibrous material under the inner membrane forms the polar ring from which subpellicular microtubules originate. One hr later the centrioles have disappeared and the nucleus has returned to the center of the organism. The conoidal complex forms the tip of a growing cytoplasmic projection, the anterior end of the ookinete. During this time an elaborate pellicle is differentiating antero-posteriorly; crystalloid formation begins with an extensive proliferation of rough endoplasmic reticulum (ER) continuous with the outer membrane of the nuclear envelope. Crystalloid particles are formed between the lamellae of the ER and collected in a sphere that is later partially surrounded by a small amount of ER. Ookinetes, differentiated 2 hr longer than the ookinetes in vitro, were obtained from the gut of the pigeon fly, Pseudolynchia maura. The differentiated pellicle of these ookinetes consists of a plasma membrane, an inner membrane layer composed of 2 appressed membranes, and in the anterior end, an electron-opaque lamina immediately under the inner membrane. Anterior to the polar ring, this lamina forms a canopy which, posteriorly, is drawn out into projecting ribs which diminish and disappear in the first third of the organism. Fifty to 60 subpellicular microtubules insert on the polar ring. Ookinetes differentiated in vitro were no more than 4 hr old. They lacked micronemes and retained a pellicular cytostome and “internal cytostomes.” The differentiation of micronemes probably occurs at a later time because they are visible after 6 hr in ookinetes in the fly gut. So many degenerating organisms appeared in vitro after 5 hr that this material was discarded.     

Observations on Crystalloid Bodies in the Pseudocoelom of Eutobrilus heptapapillatus

Eutobrilus heptapapillatus, found in a number of different sites at the mouth of the River Murray in South Australia, were examined under light and electron microscopes. The pseudocoeloms of these nematodes often contained oval crystalloid bodies containing carbohydrate, sulfur, phosphorus, and lipid. The bodies varied considerably in size up to a maximum of 10 μm long. The precise function of these crytalloids remains unknown. Nematodes having these crystalloids often also contained numerous small regular densely staining particles, about 20 nm d and occurring throughout the nematode''s body.     

Paracrystalline Arrays in the Mitochondria of the Peritrichous Ciliate Carchesium polypinum1,2

SYNOPSIS Intramitochondrial inclusions of a paracrystalline nature were observed in the peritrichous ciliate Carchesium polypinum This ciliate was found growing in the effluent of a sewage treatment plant. When paracrystalline inclusions were present, there was one per mitochondrion. A variety of profiles was encountered, all presumably of the same structure. Cross-sections revealed packed, spherical masses of 100-150 A diameter with dense walls 30-40 A thick and a variety of core densities. In more longitudinal sections the paracrystalline array appeared as long. electron-dense, finely filamentous elements oriented in parallel arrays and regularly spaced with a diameter of 60-100 A. Mitochondria tended to cluster, and between closely apposed mitochondria a dense, amorphous material was present. Numerous bud-like processes projected from mitochondria. Structural evidence, particularly the arrangement and core densities of these arrays, suggests a filamentous type of viral infection.