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.

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

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.

Initiation of placentation in the pig

1984 ◽  
Vol 42 ◽  
pp. 730-731
Author(s):  
J.L. Keys
Keyword(s):  
Electron Microscopy ◽  
Developmental Stages ◽  
Morphological Changes ◽  
Light And Electron Microscopy ◽  
Microscopic Structure ◽  
Initial Attachment ◽  
Tissue Samples ◽  
The Past ◽  
Early Developmental Stages ◽  
Early Developmental

The microscopic structure of the mature placenta in domesticated species has been described in many publications but the early developmental stages have only been studied in detail within the past decade. The earliest date previously cited for initial attachment of the porcine trophoblast to the maternal epithelium is 14 to 18 days of gestation. This investigation was undertaken to establish morphological changes in the maternal epithelium in preparation for this event.Four or 5 nulliparous gilts were slaughtered on each of d10 and d13 of the estrous cycle and pregnancy (d0=1st d of estrus), and tissue samples prepared for correlative light and electron microscopy. Samples were compared between gilts on equivalent days of the cycle/pregnancy in order to determine endometrial changes specific to pregnancy. Sites adjacent to embryos were contrasted with those lacking trophoblastic contact within the same animal to investigate whether epithelial adaptations for attachment are localized to trophoblast proximity or represent a generalized uterine response.

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.

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).

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