Spherical Cysts Research Articles

Induction of epithelial tubular morphogenesis in vitro by fibroblast-derived soluble factors

We have designed an in vitro system in which Madin-Darby canlne kidney (MDCK) epithelial cells are cocultured in collagen gels with fibroblasts under conditions precluding heterocellular contact. Using this experimental approach, we have obtained evidence that fibroblast-derived soluble factors play a crucial role in the control of epithelial morphogenesis. First, MDCK cells suspended alone in collagen gels form spherical cysts, whereas in the presence of fibroblasts they form branching tubules. Second, MDCK cells grown as a monolayer on fibroblast-containing collagen gels invade the underlying matrix, within which they form a network of tubules. Third, fibroblast-conditioned medium mimics the effects of coculture by eliciting tubulogenesis by MDCK cells. These results demonstrate the involvement of diffusible paracrine factors in morphogenetic epithelial-mesenchymal interactions and provide a strategy for their molecular characterization.

Cysticerci of Taenia mustelae in the Fox Squirrel

The liver of a fox squirrel (Sciurus niger rufiventer) contained many clear, spherical cysts approximately 1 mm in diameter throughout the parenchyma. On dissection, most of these exhibited a dense, white area with four muscular suckers at a single point on the bladder. Based on the size of the organisms, the characteristically tiny hooks on the scolex and the location of the cysts in this host, the parasites were identified as cysticerci of Taenia mustelae. This is the first report in this host. The parasites were surrounded by an intense inflammatory response consisting primarily of lymphocytes mixed with some eosinophils, and early deposition of fibrous connective tissue.

A new and unusual species of Haptoglossa

Haptoglossa elegans, isolated from soil and organic debris in New Zealand forests, is described as new. This species has no motile stage. The protoplasm inside the thallus cleaves into spherical cysts that are expelled en masse to the exterior through a solitary exit tube. Cysts are two sizes. Small cysts produce elongate, unbranched, tapering gun cells. Large cysts produce identical but larger cells; alternatively large cysts produce Y-shaped gun cells. Haptoglossa elegans is a common and aggressive parasite of bdelloid rotifers but unlike all other species of Haptoglossa, it does not attack nematodes.

Silver staining of Pneumocystis carinii in the rat's lung

The backscattered electron imaging mode of the scanning electron microscope was used to study the ontogenetic acquisition of argyrophilia in Pneumocystis carinii in rats. Silver staining continually increased from the late trophozoite to the mature cyst stage. The silver uptake began with a fine outline at the surface of the bodies of the late trophozoites; their cellular extensions, however, did not stain. The oblate precyst forms acquired the silver in heterogeneous patches. On spherical cysts the silver staining became more uniform and intense with at least one dense spot. The spherical and collapsed cysts also had short silver staining projections that may represent microvilli. Collapsed forms were paler than spherical ones and appear to be cysts that have undergone partial or complete release of sporozoites. These cell surface observations confirm and amplify previous transmission electron microscopical and histochemical studies indicating that silver staining correlates with the acquisition of the cell pellicle.

The effect of penicillin on the encystment of Bdellovibrio sp. strain W

When penicillin, and other inhibitors of peptidoglycan synthesis were added to encysting cultures of Bdellovibrio strain W, the encysting process continued, resulting in the production of cysts which were spherical in shape. Transmission electron micrographs of these spherical bdellocysts revealed the absence of an outer cyst wall. These cysts, devoid of cyst wall, were capable of germination under appropriate condition with the emergence from the prey ghost of highly motile spheroplasts. Withdrawl of the antibiotics after encystment had begun led to the production of spherical cysts that were surrounded by an outer cyst wall.

Morphogenetic clonal growth of kidney epithelial cell line MDCK.

MDCK (Madin-Darby canine kidney) cells were cultured either dispersed within hydrated collagen gel (HCG) or seeded atop a collagen substrate and then immediately overlaid with HCG. Individual cells exhibited clonal growth in three dimensions to form spherical cysts made up of a simple epithelium enclosing a fluid-filled lumen. The cells of MDCK cysts were polarized with the basolateral surface in contact with the collagen gel and the apical surface bordering the lumen. The ultrastructure of MDCK cysts showed similarities to distal nephron. The cells bore apical microvilli and solitary cilia and had occluding junctions and a simple basolateral surface. MDCK cysts increased in size (greater than 800 microns diameter) with continued culture. MDCK cysts grown between layers of HCG were stripped free of the overlying collagen to give direct access to basolateral surface membrane. Unlike monolayer culture, morphogenetic clonal growth of cell line MDCK produces a polarized cell population with a true lumenal and basolateral surface. Collagen-gel-cultured MDCK cysts provide an easily manipulable in vitro cell system that may offer unique advantages for the study of renal cell structure and function.

MDCK cysts: An in vitro model of epithelial cyst formation and growth

MDCK cells dissociated from monolayer culture were either dispersed within medium-hydrated collagen gel or seeded atop a collagen substrate which was immediately overlaid with collagen gel. Individual cells exhibited clonal growth in three dimensions to form spherical cysts in which a simple epithelium surrounded a fluid-filled lumen. The cells of MDCK cysts were polarized with apical surface bordering the lumen. MDCK cysts increased in diameter with continued culture. Maximum cyst size was dependent on seeding density and was influenced by medium composition. MDCK cysts could be isolated from the collagen substrate by digestion with collagenase. Also, collagen gel could be dissected from the cyst wall to give unrestricted access to regions of the basolateral cell surface. This novel method of renal cell culture provides a study system to model the influence of the extracellular matrix on kidney epithelial cell structure and function. It also offers an in vitro model of general application to the study of epithelial cyst formation and growth.

Two new fungal parasites of bdelloid rotifers

Haptoglossa humicola (Oomycetes) and Tolypocladium trigonosporum (Hyphomycetes) are described as new endoparasites attacking rotifers, belonging to the genera Adineta and Philodina, in soil. In H. humicola the laterally biflagellate zoospores produce spherical cysts each of which then germinates to form a specialized injection cell. The host is attacked by means of rapid injection of a sporidium through the cuticle. Each sporidium produces a thallus inside the host which at maturity functions as a zoosporangium. In T. trigonosporum, after infection, a network of curved anastomosing fertile hyphae produces a loose shell around the encysted host. Conidia are not produced under water, but in air these fertile hyphae give rise to solitary or clustered phialides and triangulate conidia.

Coccidia (Protozoa: Sporozoasida) of cats and dogs. III. The occurrence of a species of Besnoitia in cats.

Abstract Macroscopically visible spherical cysts measuring up to 260/μm in diameter and showing characteristics typical of those of the genus Besnoitia were observed in rats dosed with isosporan oocysts recovered from the faeces of a feral cat. Kittens fed these rats shed similar oocysts measuring 16.9 ± 0.1 × 14.6 ± 0.1 μm in their faeces 11–12days later. The feeding of sporulated oocysts of this coccidian to mice, rats, rabbits and guinea pigs resulted in the formation of Besnoitia cystsin all hosts except the last. Besnoitia is the fourth sporozoan genus, together with Isospora, Toxoplasma, and Sarcocystis to be recovered from New Zealand cats.

Description and first occurrence of Myxidium zealandicum (Protozoa: Myxosporidia) in the North American eel Anguilla rostrata LeSueur

Myxidium zealandicum Hine, 1975 is described from gills and kidney of the North American eel Anguilla rostrata collected from the St. Lawrence River near Quebec City and Cornwall. Cysts of M. zealandicum on gills measured up to 1 by 2 mm and in kidneys up to 15 by 20 mm. In addition to single spherical cysts, several polymorphous forms were also observed on the gills. Polymorphous cysts were not found in the kidney. Different stages of spore development were evident in gill cysts and were differentiated by means of a lead hematoxylin – fast green stain. Number and pattern of spore striations were examined by scanning electron microscopy and were highly variable. The invasion of the parasite into kidney tissue appeared to result in less physiological damage to the host than did gill invasion. The existence of this parasite, previously found in eel species in New Zealand, in a North American eel species is discussed.

An ultrastructural study of the haemopoietic organs of the silkworm, Bombyx mori

The haemopoietic organs of Bombyx larvae are located near to or attached to the imaginal wing disks in the thorax. The development of the organs, the incorporation of tritiated thymidine into the organs, and their ultrastructure were studied by light and electron microscopic methods. The haemopoietic organs increased in size and number during larval development. The size of the organs increases only during the early stages of each of the instars, and the number of the organs increases only during each apolysis to ecdysis. The volume of all mature haemopoietic organs decreases during apolysis to ecdysis, showing the release of the cells from haemopoietic organs to the haemocoel. During the fourth larval instar, both the percentages of labelled cells with tritiated thymidine and the grain densities are highest during apolysis to ecdysis. In the fifth instar, there is extremely heavy incorporation of tritiated thymidine during the 3 days preceding pupation. The haemopoietic organs are covered by an acellular sheath with openings which allow passage of cells from the organ to the blood. The organs contain spherical cysts made up of electron opaque cells. The typical cell of the cyst is characterized by a large, electron opaque nucleus containing a conspicuous nucleolus and a cytoplasm densely packed with ribosomes. These cells seem to be the generative cells of the haemocyte forming organ. Proleucocytes, plasmatocytes, granular cells, spherule cells, and oenocytoides are found floating within the haemopoietic organ and are believed to be derived from the cyst cells.

Oocystis nephrocytioides sp. nov

Ce l l s ellipsoid, asymmetrical, in extreme cases kidney-shaped, joined in two-celled (rarely four-celled) coenobia. Cel l wal l firm, colourless, dissolving completely during the forma­ tion of autospores and changing into a colourless, non-bordered mucilage which keeps the daughter cells together. No warts at the poles. Protoplast containing four chloroplasts (two in autospores, eight in mother cells), each with a central pyrenoid. Pyrenoid spherical with a continuous starch-sheath. Additional stroma-starch in the chloroplast. Storage product oil, sometimes in large droplets. Nucleus in the middle of the cell. Occasionally vacuoles are formed. Re p r o d uct ion by two (rarely four) autospores, lying crossed in the mucilage originating from the mother-cell wall. Spherical cysts in cul­ tures. Dimensions: 10-18 J.l in length, 6-10.5 J.l in breadth. Occurr e n ce : in an open-air concrete channel of the trout hatchery, Hydrobiological Institute, Ohrid, Yougoslavia.

LOCALIZATION OF CILIARY PRIMORDIA IN INDUCED ABNORMAL CYSTS OF OXYTRICHA FALLAX.

SYNOPSIS. Precystic organisms embedded in agar become abnormal cysts. Some of them are excystable rod‐like or ellipsoid forms and the others, non‐excystable fiat ones. Major axis of the rod‐like or ellipsoid cysts is parallel with the body axis of the previous precystic organisms, because when the cysts are formed the protoplast within the secreted cyst walls rotates or agitates slightly around the major axis but movement around the minor axis is precluded.The fibrillar structures appearing in excystment from abnormal cysts are bilaterally symmetrical, different from the normal spherical cysts showing radial symmetry. The two poles from which the fibrils radiate are situated opposite each other but not at the extremities of the cyst. The locus of the anterior pole corresponds to the site of oral primordia in dividers and reorganizers.When the anterior part of the original adoral membranelles (AZM) in the early precystic animals is removed, the ellipsoid cysts from the abbreviated animals show a disturbance of the anterior fibrillar arrangement. The primoidium of the future AZM runs straight from the anterior extremity of the cyst toward the uninjured posterior pole. Ellipsoid cysts from precystic animals after the posterior region is removed similarly have disturbed fibrils near the posterior extremity of the cyst. The AZM primordium then arising on excystment extends from the uninjured anterior pole toward the damaged posterior extremity of the cyst. Similar events are found also in spherical cysts from anterior and posterior fragments of precystic animals.In either case, though the initial phase of the AZM primordium shows irregular contour, leaf‐like shape is accomplished later accompanying the increase of primordial granules, while the other ciliary primordia such as undulating membrane and cirri arise at their corresponding areas. All can produce normal excysted animals.The ciliary primordia appearing upon excystment, notably that of the AZM, therefore seem to have descended from the precystic stage or foregoing trophic one.

A New Nematode Parasite, Tetrameres paucispina, from a South American Bird, Amblyramphus holocericeus

Franklin Park Zoological Garden of the City of Boston. I am indebted to Dr. Tyzzer, not only for the material but also for his generous assistance in interpreting the anatomical changes in the host following the invasion by the parasite. The material consisted of the proventriculus showing seven spherical cysts, each a little smaller than a pea, projecting outward through the proventricular wall into the peritoneal cavity. The cysts were contiguous with each other forming a cluster which, after dissecting the enclosed worm from two of the cysts, was preserved in formalin with the part of the proventriculus affected. One of the worms removed was fixed in Zenker's fluid and the other was flattened and cleared for microscopic examination. Macroscopically, the internal aspect of the wall of the proventriculus appeared normal; nor were there, aside from minor changes involving a few of the tubulo-sacular, chief glands lining this organ in the immediate vicinity of the cysts, any marked pathological lesions to be noted.

Observations on Microphallus ovatus sp. nov. from the Crayfish and Black Bass of Lake Chautauqua, N. Y.

The recent account by Yoshida (1916: 76-82) of an unnamed trematode infesting the liver, ovary and other tissues of Japanese crustacean, living in burrows between tides on the seashore near Osaka, recalls some observations which I made several years ago, but which have never as yet been published. Though Yoshida did not designate the form which he described, his account and drawings show it to be a member of the genus Microphallus (Ward, 1901:184). For convenience, I will refer to it as M. japonicus, which name I would propose to call it. Especial interest attaches to the case of M. japonicus as another instance of that remarkable correspondence between parasite and host organ infected which has been noticed by various writers and in particular by Johnston (1913:272) in Australian frogs. M. japonicus is the third case now known where the liver or adjoining thoracic viscera of the crayfish or some other crustacean is infected by a species of Microphallus. I first noticed the Chautauqua species in the crayfish in the summer of 1898 and saw its close relationship with M. opacus of Ward (1894: 173 and 1901:175). I found it later also in the stomach of the black bass and of the bullhead from Lake Chautauqua. In the liver of the crayfish (Fig. 1) it forms large whitish spherical cysts among the tubular cecae of the infected organ. In August, 1902, it was found in every individual of a group of twenty-five examined. In one instance 22 cysts were found on one side and 18 on the other, totalling 40 cysts for the organ. One case, very badly infected, showed about 100 cysts. In the stomach of the black bass partly digested crayfish are often found, and specimens of the worm in various stages are seen which are thus traced to the crayfish as the source of infection. The bass is more often infected than the bullhead, the diet of the latter regularly being more largely molluscan. The Chautauquan form shows marked resemblances to M. opacus, but there are certain differences which seem at present to justify distinguishing them and I am proposing to give it the name M. ovatus in allusion to its shape.