Ultrastructural description of an unidentified apicomplexan oocyst containing bacteria-like hyperparasites in the gill of Crassostrea rizophorae.

Oocysts of an unidentified coccidian are reported in this study to parasitize the gills of the oyster Crassostrea rizophorae (Mollusca, Bivalvia) collected near the city of Recife (Itamaracá Island, 07 degrees 38' 00" S, 34 degrees 48' 06" W), Brazil. Oocysts appeared as light and dense forms, both containing rod-shaped, bacteria-like hyperparasites (BL). Both light and dense oocysts were spherical, 4.3 to 4.7 pm in diameter, but denser oocysts had irregular contours. Both forms consisted of a thick dense wall (approximately 165 nm thick) consisting of 3 layers. The outermost, a dense and irregular layer about 25 nm thick, possessed numerous bead-like structures and some slender conical projections (up to 1.5 microm long). The inner layer of the wall was formed by a dense and homogenous layer about 125 nm thick. Between these 2 layers, a thin light layer about 12 nm thick was present. Uninucleated sporocysts occupied the internal space of the oocyst and contained some rod-shaped BL and mitochondria surrounded by numerous ribosome-like particles. The dense forms of the oocysts showed the same structures described in the lighter forms and appeared to be the final maturation form of the oocysts. Free sporozoites were occasionally observed among oocysts.

Ultrastructural studies of spermiogenesis of the clamLucina pectinata (Bivalvia, Lucinidae) from Northern Brazil

Spermatogenesis and sperm ultrastructure of the clam Lucina pectinata (Lucinidae) from northern Brazil were studied using light and transmission electron microscopy. The uniflagellate spermatozoa are grouped into characteristic rings within somatic cells (Sertoli-like cells), with the acrosome oriented toward the peripheryof these cells. The spermatozoa are long cells of the primitive type (ect-aquasperm) with a total length of 50.2 ± 2.5 mm, consisting of head (acrosome + nucleus), midpiece and tail. Acrosome is formed by an, acrosomal vesicle with a conical cylinder-like shaped (0.9 ± 0.1 mm length and 0.4 ± 0.1 mm in basal diameter) having a deeply infolded basis occupied by the subacrosomal space, containing flocculent material without axial rod. The acrosomal vesicle is formed by a membrane-bounded containing a broad basal ring of electron-dense material. The nucleus (7.5 ± 0.8 mm long) is an elongated, subcylindrical rod-shaped, slightly and gently curved, with a basal invagination (0.2-0.4 mm). It contains dense chromatin without any electron-lucent lacunae.The midpiece (1.0 ± 0.3 mm long; 1.1 ± 0.2 mm width) consist of four equal mitochondria located at the same level, surrounding two centrioles arranged at right angles. The proximal centriole lies at 90° relative the distal centriole and sperm longitudinal axis. The tail (40.5 ± 2.1 mm long) contains the common 9 + 2 pattern which in tapering end piece is successively reduced and sheated by the plasmalemma.

Acanthocollaritrema umbilicatum Travassos, Freitas & Bührnheim, 1965 (Digenea: Acanthocollaritrematidae) from the common snook, Centropomus undecimalis, from Itamaracá, state of Pernambuco, Brazil.

Acanthocollaritrema umbilicatum Travassos, Freitas and Bührnheim, 1965, is the only species of Acanthocollaritrematidae described up to the moment. The systematic position of this species and the validity of the family has been questioned by the possible presence of a gonotyl and a genital atrium associated to the acetabulum. In this paper, specimens of this trematode, collected from Centropomus undecimalis cultivated at Itamaracá, State of Pernambuco, northeast Brazil, were studied under optical and scanning electron microscopy, and compared with available sintypes. Gonotyl and genital atrium were not observed and both family and species are considered valid taxonomic entities. A. umbilicatum is redescribed with the addition of new morphological information.

The effect of short-wavelength ultraviolet light on antigens, lectin receptors and the ultrastructure of Crithidia fasciculata.

Crithidia fasciculata is an important trypanosomatid parasite commonly affecting insects and is used extensively as a model for the study of the biochemistry, ultrastructure and organization of the kDNA network of trypanosomatids. The present study describes the evolution of UV-induced morphological changes detectable by transmission electron microscopy in Crithidia fasciculata. Although only rare and minor changes in kinetoplast DNA were demonstrable 7 h after UV irradiation, alterations of this organelle were present in almost all flagellates observed 24 h and 48 h after irradiation. Other cell structures were apparently undamaged. Ultrastructural changes in kDNA did not correspond to changes in antigenicity of protein bands in western blotting against serum from Chagas' disease patients or in the presence of 3 different lectin receptors on the surface of the parasite.

The effect of short-wavelength ultraviolet light on antigens, lection receptors and the ultraestructure of Crithidia fasciculata

Crithidia fasciculata is an important trypanosomatid parasite commonly affecting insects and is used extensively as a model for the study of the biochemistry, ultrastructure and organization of the kDNA network of trypanosomatids. The present study describes the evolution of UV-induced morphological changes detectable by transmission electron microscopy in Crithidia fasciculata. Although only rare and minor changes in Kinetoplast DNA were demonstrable 7 h after UV irradiation, alterations of this orgtanelle were present in almost al flagellates observed 24 h and 48 h after irradiation. Other cell structures were apparently undamaged. Ultrastructural changes in kDNA did not correspond to changes in antigenicity of protein bands in western blotting against serum from Chagas' disease patients or in the presence of 3 different lectin receptors on the surface of the parasite

[Occurrence of Campylobacter pylori in patients with gastritis and peptic ulcer]. / Ocorrência do Campylobacter pylori em pacientes com gastrite e úlcera péptica.

Endoscopic biopsies from the gastric antrum and margin of peptic ulcers (gastric and duodenal) were obtained from 56 patients for histologic and microbiologic studies in order to establish the occurrence of Campylobacter pylori. Thirty nine of them had antral gastritis and in 37 (94.8%) the bacteria was detected. In 17 cases with normal mucosa the culture was positive in only 2 of them (p less than 0.01). Patients with duodenal and gastric ulcer had a 100% and 88.8%, respectively, of positivity to C. pylori at samples from the margin of the lesions. Bacteriologic findings were similar to those described in the literature. At the electronic microscopy bacilli were found near or adhering to the cellular surface without signs of intraepithelial penetration. This study confirms the association between C. pylori and gastritis and peptic gastroduodenal ulcer.

Morphometric study of the plasmalemmal vesicles of the capillaries of the rat cerebellum, heart, diaphragm and lung during perinatal growth.

1. Morphometric techniques were used to determine the variation in number of plasmalemmal vesicles, their area and the area of the endothelium in capillaries of the cerebellum, heart, diaphragm and lung of rat fetuses aged 17, 19, 20 and 21 days and of newborn rats. 2. A curve fitting procedure showed that the evolution of vesicle number could be properly expressed by equations of the type y = aoekx, where y = number of vesicle images per capillary section or number of vesicles per micron3 of capillary wall, and x = age in days. The time necessary for the numerical density of the vesicles to duplicate in the capillary wall is on average 1.1-1.3 days in the lung, 1.4-1.9 days in the muscular organs and 2.3 days in the cerebellum. 3. Capillary maturation was characterized by thinning of the endothelium, especially for those at the base of the lung, and by increased numbers of vesicles. 4. The ratios: number of plasmalemmal vesicle images/endothelial area, plasmalemmal vesicle image area/endothelial area, and number of plasmalemmal vesicle images/plasmalemmal image area increased with age. The third parameter tended to reach 1 due to the increased area of the vesicles as a function of their numbers, even though there was a decrease in individual vesicle size.

Schistosoma mansoni: structural damage after treatment with oxamniquine.

The effects of a single dose (100 mg/kg-body weight of mouse) of oxamniquine on the worm's tegument and paranchyma in relation to the process of immunological granulomatous reaction of the host's liver are described under light and electron microscopy (EM). The lesions caused by the drug are sequentially and simultaneously described in form of swelling, surface bulble and disruption with erosions. Ulceration in the tubercules with loss of spines is often more extensive and severe in male worms and concentration of host's mononuclear cells is observed. The possible role of host's immune response is discussed.