An electron microscope study of the body wall of the third-stage larva of Nippostrongylus brasiliensis

Parasitology ◽  
1966 ◽  
Vol 56 (1) ◽  
pp. 127-135 ◽  
Author(s):  
D. L. Lee
Keyword(s):  
Plasma Membrane ◽  
Electron Microscope ◽  
Basement Membrane ◽  
Stage Larva ◽  
Nippostrongylus Brasiliensis ◽  
The Third ◽  
Third Stage ◽  
Matrix Layer ◽  
Inner Cortex ◽  
Excretory Canal

The cuticle of the third-stage larva of Nippostrongylus brasiliensis consists of seven layers: an outer triple-layered membrane, a double-layered outer cortex, an inner cortex, a matrix layer, a striated layer and two fibril layers. In each ‘annule’ two fibres run transversely around the nematode and lie between the inner cortex and the matrix layer. There is no basement lamella.The hypodermis is a thin layer between the muscles and the cuticle, but expands to form the dorsal, ventral and lateral cords. The nerves lie between the plasma membrane of the hypodermis and the basement membrane or between the plasma membrane of the hypodermis and the sarcolemma of the muscles. The muscle cells are typical of those described previously for nematodes. The ‘myofibrils’ are apparently similar to those of Ascaris.An excretory canal is present in each lateral cord and is enclosed by the basement membrane but is not embedded in the hypodermal tissue. Numerous small vesicles appear to move across the wall of the excretory canal and open into the central lumen.I am grateful to Dr P. Tate, Dr R. W. Horne and Dr K. A. Wright for helpful discussions, to Professor C. P. Read and Dr A. Enders for the use of facilities at Rice University, Houston, Texas and to Professor J. D. Boyd for permission to use the electron microscope in the Department of Anatomy. Thanks are also due to Mr A. J. Page for technical assistance.

Electron-microscopical observations on the body wall of the third-stage larva of Haemonchus placei

Parasitology ◽  
1970 ◽  
Vol 60 (3) ◽  
pp. 411-416 ◽  
Author(s):  
Kenneth Smith
Keyword(s):  
Body Wall ◽  
Muscle Cells ◽  
Cortical Layer ◽  
The Body ◽  
Stage Larva ◽  
Dense Layer ◽  
The Third ◽  
Third Stage ◽  
Electron Microscopical ◽  
Inner Cortex

SUMMARYThe ultrastructure of the body wall of the third-stage larva of Haemonckus placei was studied. The cuticle was found to consist of eight layers: a thin outer layer, a membrane-bounded layer, an electron-dense layer, a thin irregular layer, an inner cortical layer, a matrix layer, a striated layer and a fibril layer. Interposed between the inner cortex and matrix were two transverse fibres.The region between the fibril layers and the contractile part of the muscle cells was occupied by the hypodermis, which enlarged to form the dorsal, ventral and lateral cords. Within the cords lay hypodermal cells, nerves, crystalline inclusions and an excretory canal.The sarcoplasmic part of the muscle cells was rich in glycogen and contained numerous mitochondria. Myofibrils of two types were present in the contractile part of the cell.I am grateful to Dr D. W. Brocklesby for his help and advice and to Mr E. Harness for the production and supply of third-stage larvae. I would also like to thank Dr D. L. Lee and Mr W. G. MacMillan for helpful discussions.

Studies on the life-history of Bunostomum phlebotomum (Railliet, 1900), a hookworm parasite of cattle

Parasitology ◽  
1946 ◽  
Vol 37 (3-4) ◽  
pp. 192-201 ◽  
Author(s):  
J. F. A. Sprent
Keyword(s):  
Infective Larva ◽  
Stage Larva ◽  
Fourth Stage ◽  
Larval Stages ◽  
The Third ◽  
Third Stage ◽  
History Of ◽  
Time Required ◽  
Cutaneous Blood ◽  
Fourth Stage Larva

A description is given of the processes of copulation, formation of the egg and spermatozoon, cleavage, embryogeny and hatching in B. phlebotomum. These processes were found to be essentially similar to those in other strongyle nematodes.The anatomy of the first three larval stages is described and the observations of Conradi & Barnette (1908) and Schwartz (1924) were largely confirmed.Penetration of the skin of calves by the infective larva was observed histologically. The larvae were found to have reached the dermis within 30 min. and to have penetrated the cutaneous blood vessels within 60 min. of application to the skin. The larvae were found in the lung where the third ecdysis was in progress 10 days after penetration of the skin. A description is given of the growth of the third-stage larva in the lung, the changes which take place during the third ecdysis, and the anatomy of the fourth-stage larva.The fourth-stage larvae exsheath in the lungs and travel to the intestine. After a period of growth in which sexual differentiation takes place, the fourth ecdysis occurs and the adult parasite emerges. The time required for the attainment of maturity was found to be somewhere between 30 and 56 days after penetration of the skin.This paper was written at the Ministry of Agriculture and Fisheries Veterinary Laboratories, Wey-bridge, and the writer would like to express his gratitude to the Director, Prof. T. Dalling, also to Dr W. R. Wooldridge, chairman of the Council of the Veterinary Educational Trust for their help and encouragement. The writer's thanks are also due to Dr H. A. Baylis, Prof. R. T. Leiper and Dr E. L. Taylor for their advice and help on technical points, and to Mr R. A. O. Shonekan, African laboratory assistant, for his able co-operation.

New information about the third stage larva and larval habitat of Microdon (Chymophila) bruchi Shannon, 1927 (Diptera, Syrphidae) from Argentina

2019 ◽  
Vol 53 (45-46) ◽  
pp. 2833-2853
Author(s):  
Guillermo P. López-García ◽  
Menno Reemer ◽  
Guillermo Debandi ◽  
Ximo Mengual
Keyword(s):  
Larval Habitat ◽  
Stage Larva ◽  
The Third ◽  
New Information ◽  
Third Stage

Description of the larva of Chalcosoma atlas (L.) (Coleoptera, Scarabaeidae, Dynastinae) from Malaysia

1976 ◽  
Vol 66 (2) ◽  
pp. 189-193 ◽  
Author(s):  
G. O. Bedford
Keyword(s):  
Stage Larva ◽  
Breeding Sites ◽  
Oryctes Rhinoceros ◽  
The Third ◽  
Third Stage

AbstractThe third-stage larva of Chalcosoma atlas (L.) collected in Malaysia is described, with illustrations, and a key is provided to distinguish larvae of this species from those of Oryctes rhinoceros (L.) and Xylotrupes gideon beckeri Schaufuss, all of which occur in similar breeding sites.

A technique for skin application of exact doses ofNippostrongylus brasiliensisto rats

1990 ◽  
Vol 64 (1) ◽  
pp. 15-22 ◽  
Author(s):  
N. R. Tindall ◽  
P. A. G. Wilson
Keyword(s):  
Experimental Design ◽  
Quantitative Agreement ◽  
Nippostrongylus Brasiliensis ◽  
The Third ◽  
Third Stage ◽  
The Mean ◽  
Conventional Methods ◽  
Polythene Film ◽  
New System

ABSTRACTConventional methods for percutaneous infection of rats using third-stage juveniles ofNippostrongylus brasiliensiswhich have been artificially stimulated to exsheath lead to highly variable, and relatively poor, establishment in the intestine. A new system has been developed in which larvae applied to the skin still remain partially sheathed, as they would be in nature. Cultures of the freeliving stages of the parasite contain an annulus of clear, colourless polythene film to which some of the third-stage juveniles attach. Rats are infected with an individually counted, exact dose applied to the skin on polythene. Using this technique (‘EDT20Nb’), consistently high values for the mean proportion of the dose that becomes establishedhave been obtained, along with a variance well below the normally accepted level (from a total of 73 rats in 12 separate assays). In particular, the added component of variance between assays in this study was insignificant, so that the probability of quantitative agreement in replicate experiments based on the method is high. It is recommended for an experimental design in which small numbers of parasites can be used.

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