Ultrastructure of Cercarial Tails

1974 ◽  
Vol 32 ◽  
pp. 180-181
Author(s):  
Richard S. Demaree ◽  
Donald M. Wootton
Keyword(s):  
Schistosoma Japonicum ◽  
Intermediate Hosts ◽  
Suitable Host ◽  
Ultrastructural Studies ◽  
Tail Structure

Cercariae (juvenile trematodes with tails) emerge from mollusk intermediate hosts and swim toward definitive hosts or encystment objects. The locomotor power is furnished by the tail. Upon reaching a suitable host or encystment object, the tail is cast off and the cercariae penetrate and/or encyst. Ultrastructural studies of cercariae are sparse. There is even lessUltrastructural studies of cercariae are sparse. There is even less information about the tail structure; and body-to-tail morphology has been documented only for Acanthatrium oregonense and Schistosoma japonicum.

Egg ultrastructure of the amabiliid cestode Tatria biremis Kowalewski, 1904 (Cyclophyllidea, Amabiliidae), with an emphasis on the oncospheral envelopes

2013 ◽  
Vol 58 (3) ◽  
Author(s):  
Vasyl Tkach ◽  
Zdzisław Świderski ◽  
Daniel Młocicki
Keyword(s):  
Cell Types ◽  
Life Cycles ◽  
Intermediate Hosts ◽  
Outer Envelope ◽  
Ultrastructural Studies ◽  
Egg Maturation ◽  
Ultrastructural Characteristics ◽  
Egg Envelopes ◽  
Host Infection ◽  
Inner Envelope

AbstractThis is the first report on the ultrastructure of eggs in the cestode family Amabiliidae Braun, 1900. The gravid proglottides of Tatria biremis easily detach from the strobila. Their thick-walled saccate uterus contains numerous rounded or oval eggs measuring about 30-32 μm in diameter. In the early preoncospheral phase, three primary embryonic envelopes are formed around the developing and differentiating embryos, namely: (1) vitelline capsule originating from vitellocyte material; (2) outer envelope formed by two macromeres, and (3) inner envelope originating from a fusion of three mesomeres. Thus, both the outer and inner envelopes of T. biremis eggs are cellular in origin and syncytial in nature. During egg maturation, the three primary embryonic envelopes undergo differentiation into fully formed oncospheral or egg envelopes. Most significant changes were observed in the inner envelope which becomes progressively subdivided into 3 sub-layers: the extra-embryophoral sub-layer, the embryophore, and the intra-embryophoral sub-layer, containing mesomere nuclei. The mature hexacanth is covered by a thin layer of the oncospheral tegument. Within the infective hexacanth larva, five cell types were distinguished: (1) a binucleated subtegumental cell; (2) U-shaped penetration gland; (3) nerve cells; (4) somatic cells representing the myocytons of both somatic and hook musculature, and (5) large germinative cells. Ultrastructural characteristics of T. biremis eggs are compared with those described in representatives of other cestode taxa. Since the functional ultrastructure of cestode egg envelopes is defined by multiple factors such as the type of life cycles, habitats and behaviour of the intermediate hosts, mode of the intermediate host infection, etc., ultrastructural studies of the greater diversity of cestodes are needed to obtain comparative data for fruitful analysis of cyclophyllidean cestode adaptations to their diverse life cycles.

The Parasitological and Pathological Significance of Arrested Development in Nematodes

1953 ◽  
Vol 27 (3-4) ◽  
pp. 199-205 ◽  
Author(s):  
E. L. Taylor ◽  
J. F. Michel
Keyword(s):  
Intermediate Host ◽  
Larval Stage ◽  
Final Host ◽  
Parasitic Nematodes ◽  
Intermediate Hosts ◽  
Suitable Host ◽  
Free Living ◽  
Arrested Development ◽  
Essential Requirement

In summarising, therefore, we conclude that a tendency to become dormant during the larval stage, which is so characteristic a feature of the free-living larvae of parasitic nematodes and is an essential requirement in their use of intermediate hosts is not an uncommon occurrence during their life in the final host. Its purpose in each instance is essentially the same, i.e. to carry it through a period in which the environment is unsuited to development; on the ground, for instance, where it waits for a suitable host, as a parasite of an intermediate host, where it waits for a suitable final host, or in a resistant final host where inhibited development serves the parasite in enabling it to wait until some depression of the host's state of resistance allows it to grow to maturity.

Scanning and Transmission Electron Microscopy of Endomentrium in Women Wearing TCu-380-A IUD 's

1977 ◽  
Vol 35 ◽  
pp. 666-667
Author(s):  
A. Gonzalez Angulo ◽  
R. Berlioz ◽  
R. Aznar
Keyword(s):  
Copper Wire ◽  
Uterine Cavity ◽  
Morphological Evidence ◽  
Secretory Phase ◽  
Ultrastructural Studies ◽  
Proliferative Phase ◽  
Contraceptive Devices ◽  
Transmission Electron ◽  
Intrauterine Contraceptive ◽  
Myelin Figure

Recent ultrastructural studies on endometrial tissues from women wearing copper, wire intrauterine devices have disclosed morphological evidence of impaired glycogen degradation and secretion resulting in interference with the viability of blastocysts. Reduced microapocrine secretion observed with the scanning electron microscope supports this (1). In addition, organelle modifications have been observed in the epithelial cells of these women. The changes are seen in biopsies taken in the proliferative phase of the cycle and consist of mitochondrial vacuolation and myelin figure formation. These modifications disappear in the secretory phase and therefore have been regarded as reversible (2).The aim of the present studies was to investigate surface epithelial changes as well as organelle modifications in relation to the site of contact with an IUD that releases greater amounts of copper. Endometrial tissue was obtained from the uterine cavity of four young women wearing TCu-380-A intrauterine contraceptive devices for 4-6 weeks.

The Cellular Origin in Atheromatous Lesion

1970 ◽  
Vol 28 ◽  
pp. 202-203
Author(s):  
T. M. Murad ◽  
H. A. I. Newman ◽  
K. F. Kern
Keyword(s):  
Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Rabbit Aorta ◽  
Mixed Population ◽  
The Other ◽  
Cellular Origin ◽  
Ultrastructural Studies ◽  
Atherosclerotic Lesions ◽  
Show Evidence ◽  
Early Lesion

The origin of lipid containing cells in atheromatous lesion has been disputed. Geer in his study on atheromatous lesions of rabbit aorta, suggested that the early lesion is composed mainly of lipid-laden macrophages and the later lesion has a mixed population of macrophages and smooth muscle cells. Parker on the other hand, was able to show evidence that the rabbit lesion is primarily composed of lipid-laden cells of smooth muscle origin. The above studies and many others were done on an intact lesion without any attempt of cellular isolation previous to their ultrastructural studies. Cell isolation procedures have been established for atherosclerotic lesions through collagenase and elastase digestion Therefore this procedure can be utilized to identify the cells involved in rabbit atheroma.

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