RESUMO
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.
Assuntos
Coccídios/microbiologia , Brânquias/parasitologia , Oocistos/ultraestrutura , Ostreidae/parasitologia , Animais , Brasil , Coccídios/ultraestrutura , Microscopia EletrônicaRESUMO
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.
Assuntos
Animais , Bivalves/anatomia & histologia , Espermatogênese/fisiologia , Espermatogênese , Brasil , Microscopia Eletrônica de Transmissão , Moluscos/ultraestruturaRESUMO
Using transmission electron microscopy, gold-labeled lectins, morphometry and enzyme-linked lectin assay, we could show that treatment of promastigotes of Leishmania donovani chagasi with trypsin did not interfere with the binding of lectins (concanavalin A, peanut agglutinin, wheat germ agglutinin and Ricinus communis agglutinin) to the parasite surface. These observations are in agreement with results we previously obtained using a biochemical approach. Treatment of fixed promastigotes with 2-mercaptoethanol induced a significant increase in the density of concanavalin A (Con A) receptors on the surface of L. d. chagasi in relation to the control. We suggest that this increase is due to the unfolding of one or more surface glycoproteins after cleavage of disulfide bonds between cystein residues in adjacent protein loops, exposing second-order Con A receptors that are otherwise hidden in the protein quaternary structure.
Assuntos
Glicoproteínas/metabolismo , Leishmania donovani/efeitos dos fármacos , Mercaptoetanol/farmacologia , Tripsina/farmacologia , Animais , Lectinas/metabolismo , Leishmania donovani/ultraestrutura , Microscopia Eletrônica , Receptores Mitogênicos/metabolismoRESUMO
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.
Assuntos
Endotélio Vascular/ultraestrutura , Animais , Capilares/ultraestrutura , Cerebelo/irrigação sanguínea , Vasos Coronários , Diafragma/irrigação sanguínea , Endotélio Vascular/embriologia , Feminino , Pulmão/irrigação sanguínea , Gravidez , Ratos , Ratos EndogâmicosRESUMO
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.