Studies on the helminth fauna of Alaska. LI. Observations on eggshell formation in some diphyllobothriid cestodes

1972 ◽  
Vol 50 (5) ◽  
pp. 585-592 ◽  
Author(s):  
Douglas K. Hilliard
Keyword(s):  
Electron Microscopy ◽  
Life Cycle ◽  
Light And Electron Microscopy ◽  
Helminth Fauna ◽  
Taxonomic Significance ◽  
Eggshell Formation ◽  
Salt Ions ◽  
Quinone Tanning

Formation and structure of the eggshell were studied with light and electron microscopy in 13 species of diphyllobothriid cestodes. In those having marine intermediate and final hosts, the shell of the fully developed egg is deeply pitted; the eggs as they first appear in the uterus are up to four times the size of mature eggs, and are asymmetrical, thin-shelled, cohesive, and plastic. As they move down the uterus, they become smaller, the shell thickens, the pits enlarge and deepen penetrating the shell to the lipoprotein layer, and the opercular suture develops. The pits may be formed by coalescence of proteins before quinone tanning. Hatching of eggs from such cestodes depends upon salinity rather than light; the pits may provide the means by which salt ions are conveyed to the mechanism that controls hatching. In cestodes having the aquatic phase of their life cycle in freshwater, the eggshells are only superficially pitted, and hatching usually is mediated by light. Origin of the pits in relation to eggshell formation is discussed, as is their possible phylogenetic and taxonomic significance.

Life cycle of tetrodotoxin-producing Bacillus sp. on solid and liquid medium: Light and electron microscopy studies

2016 ◽  
Vol 42 (3) ◽  
pp. 252-257 ◽  
Author(s):  
O. A. Shokur ◽  
T. Yu. Magarlamov ◽  
D. I. Melnikova ◽  
E. A. Gorobets ◽  
I. A. Beleneva
Keyword(s):  
Electron Microscopy ◽  
Life Cycle ◽  
Liquid Medium ◽  
Light And Electron Microscopy ◽  
Bacillus Sp

Changes in structure of the frontal filament in sequential developmental stages of Caligus elongatus von Nordmann, 1832 (Crustacea, Copepoda, Siphonostomatoida)

1993 ◽  
Vol 71 (5) ◽  
pp. 889-895 ◽  
Author(s):  
W. Piasecki ◽  
B. M. MacKinnon
Keyword(s):  
Electron Microscopy ◽  
Life Cycle ◽  
Developmental Stages ◽  
Light And Electron Microscopy ◽  
Frontal Organ ◽  
Frontal Filament

The frontal filament of larval and adult Caligus elongatus was examined using light and electron microscopy. No trace of a frontal filament was evident in eggs, nauplii, or young copepodids. The structure develops in older copepodids in a cuticular pocket in the cephalothorax. Upon infecting a fish, the filament extrudes and attaches permanently to the host. The subsequent chalimus stages inherit the filament. Before moulting, the "frontal organ" produces an extension lobe, which is attached to the old filament by each subsequent chalimus stage during the moult. The structure of the frontal filament is described and illustrated, as well as some details of the frontal organ. Some new terms are proposed for the elements of the filament and the organ. The suggestion is made that the life cycle of C. elongatus includes five, not four, chalimus stages.

Developmental stages of Cyclospora talpae in the liver and bile duct of the mole (Talpa europaea)

Parasitology ◽  
1990 ◽  
Vol 101 (3) ◽  
pp. 345-350 ◽  
Author(s):  
H. A. Mohamed ◽  
D. H. Molyneux
Keyword(s):  
Electron Microscopy ◽  
Life Cycle ◽  
Bile Duct ◽  
Epithelial Cells ◽  
Room Temperature ◽  
Mononuclear Cells ◽  
Developmental Stages ◽  
Light And Electron Microscopy ◽  
Ultra Structure ◽  
Talpa Europaea

SUMMARYThe completed life-cycle of Cyclospora talpae, an extra-intestinal coccidian (Apicomplexa) of the liver of the mole (Talpa europaea). is reported. Oocysts sporulated within 12–14 days at room temperature (20–22 °C). Both macro- and micro-gametocytes developed independently within the nucleus of epithelial cells lining the bile duct as demonstrated by both light and electron microscopy. Merogony was seen in the mononuclear cells in the capillary sinusoids of the liver. Merozoites showed the typical ultrastructural features of the Apicomplexa. The life-cycle of C. talpae and the ultra-structure of the gametogonic and merogonic stages are reported; the ultrastructure of the merozoites is reported as the first description of this stage for the genus Cyclospora.

The life-cycle of Syphacia muris Yamaguti (Nematoda: Oxyuroidea) in the laboratory rat

1986 ◽  
Vol 60 (1) ◽  
pp. 39-46 ◽  
Author(s):  
J. W. Lewis ◽  
J. D'silva
Keyword(s):  
Electron Microscopy ◽  
Life Cycle ◽  
Wistar Rats ◽  
Light And Electron Microscopy ◽  
Larval Stages ◽  
Laboratory Rat ◽  
Syphacia Muris ◽  
First Time

AbstractThe life-cycle of Syphacia muris is described in primary infections of Wistar rats. The life-cycle of S. muris is completed within seven days and no moults were discovered inside the egg. Instead each of two moults were observed outside the egg up to 24 and 40 hours after infection, and TEM studies suggest a third moult occurs up to 64 hours. The development and maturation of the larval stages are described for the first time using both light and electron microscopy. Differences in the size and growth of female S. muris compared with previously published figures could be due to differences in the strains of rats used.

Asci of the Pezizales. VI. The apical apparatus of Morchella esculenta, Helvella crispa, and Rhizina undulata. General discussion

1978 ◽  
Vol 56 (24) ◽  
pp. 3069-3082 ◽  
Author(s):  
Don A. Samuelson
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Light And Electron Microscopy ◽  
The Other ◽  
Present Series ◽  
Lipid Bodies ◽  
Taxonomic Significance ◽  
Taxonomic Relatedness ◽  
Morchella Esculenta ◽  
Bitunicate Ascus

Morphological, developmental, and cytochemical examinations were made with light and electron microscopy on the apical apparatuses of Morchella esculenta, Helvella crispa, and Rhizina undulata, all species with large, stipitate apothecia. Ascus tips in R. undulata were markedly thinner walled than the rest of the ascus, while those in M. esculenta and H. crispa were slightly thinner than the rest of the ascus wall. Lipid bodies were detected in developing asci of H. crispa and M. esculenta. Their unique occurrence in asci of members of the Morchellaceae and Helvellaceae may have taxonomic significance. With the electron microscope, opercula were distinguished cytochemically in all three species. In H. crispa and M. esculenta dehiscent zones were found to be restricted in the inner layer of the ascal wall. Characters of the apical apparatuses of H. crispa and M. esculenta suggest greater taxonomic relatedness between these species than with any other operculate group. The apical apparatus of R. undulata differed notably from the other species.The present series of studies has demonstrated distinct variability of the operculate ascus and its apical apparatus in morphology, cytochemistry, and development. Several major forms of the apical structures were observed. These examinations support the chemotaxonomic and cytological investigations on representatives of the Pezizales made previously by Arpin and Berthet. Outside of the Thelebolaceae, members of the Pezizales are chiefly characterized by the operculate dehiscence of their asci. Members of the Thelebolaceae eject their spores through a variety of dehiscent mechanisms. Present examinations of those representatives of the Thelebolaceae with functionally operculate apparatuses, i.e., Lasiobolus and Coprotus, support their transferrance to the Pyronemaceae. Taxa which form nonoperative opercula, i.e.,Ascozonus and Trichobolus, also show closer affinities with the Pyronemaceae than with the nonoperculate representatives of the Thelebolaceae. The nonoperculate members of the Thelebolaceae apparently do not belong in the operculate Discomycetes. The operculate ascus wall is structurally compared with the pored and bitunicate ascus walls. The terms 'bitunicate' and 'unitunicate' are redefined.

The Morphology of Vacuolated Cells in the Liver Following Administration of Vitamin A.

1973 ◽  
Vol 31 ◽  
pp. 408-409
Author(s):  
Odell T. Minick ◽  
Hidejiro Yokoo ◽  
Fawzia Batti
Keyword(s):  
Electron Microscopy ◽  
Body Weight ◽  
Vitamin A ◽  
Light And Electron Microscopy ◽  
Liver Cells ◽  
Prominent Feature ◽  
Vascular Space ◽  
Vacuolated Cell ◽  
Vacuolated Cells ◽  
Vacuolated Cytoplasm

Vacuolated cells in the liver of young rats were studied by light and electron microscopy following the administration of vitamin A (200 units per gram of body weight). Their characteristics were compared with similar cells found in untreated animals.In rats given vitamin A, cells with vacuolated cytoplasm were a prominent feature. These cells were found mostly in a perisinusoidal location, although some appeared to be in between liver cells (Fig. 1). Electron microscopy confirmed their location in Disse's space adjacent to the sinusoid and in recesses between liver cells. Some appeared to be bordering the lumen of the sinusoid, but careful observation usually revealed a tenuous endothelial process separating the vacuolated cell from the vascular space. In appropriate sections, fenestrations in the thin endothelial processes were noted (Fig. 2, arrow).

Control of Autogenous Vein Grafts Prior to Reimplantation, By Electron Microscopy

1972 ◽  
Vol 30 ◽  
pp. 106-107
Author(s):  
John H. L. Watson ◽  
John L. Swedo ◽  
M. Vrandecic
Keyword(s):  
Electron Microscopy ◽  
Light And Electron Microscopy ◽  
Physiological Saline ◽  
Experimental Conditions ◽  
Vein Grafts ◽  
Arterial Blood ◽  
Saphenous Veins ◽  
Autogenous Vein ◽  
Control Of Parameters ◽  
Post Implantation

The ambient temperature and the nature of the storage fluids may well have significant effects upon the post-implantation behavior of venus autografts. A first step in the investigation of such effects is reported here. Experimental conditions have been set which approximate actual operating room procedures. Saphenous veins from dogs have been used as models in the experiments. After removal from the dogs the veins were kept for two hours under four different experimental conditions, viz at either 4°C or 23°C in either physiological saline or whole canine arterial blood. At the end of the two hours they were prepared for light and electron microscopy. Since no obvious changes or damage could be seen in the veins by light microscopy, even with the advantage of tissue specific stains, it was essential that the control of parameters for successful grafts be set by electron microscopy.

Ultrastructure of two neoplasms in culture compared with original biopsies

1984 ◽  
Vol 42 ◽  
pp. 50-51
Author(s):  
Joseph M. Harb ◽  
James T. Casper ◽  
Vlcki Piaskowski
Keyword(s):  
Electron Microscopy ◽  
Tissue Culture ◽  
Biopsy Specimen ◽  
Cultured Cells ◽  
Light And Electron Microscopy ◽  
Human Tumor ◽  
Soft Agar ◽  
Human Tumor Cells ◽  
Morphological Distinction ◽  
Tumor Types

The application of tissue culture and the newer methodologies of direct cloning and colony formation of human tumor cells in soft agar hold promise as valuable modalities for a variety of diagnostic studies, which include morphological distinction between tumor types by electron microscopy (EM). We present here two cases in which cells in culture expressed distinct morphological features not apparent in the original biopsy specimen. Evaluation of the original biopsies by light and electron microscopy indicated both neoplasms to be undifferentiated sarcomas. Colonies of cells propagated in soft agar displayed features of rhabdomyoblasts in one case, and cultured cells of the second biopsy expressed features of Ewing's sarcoma.

Sign in / Sign up

Export Citation Format

Share Document