Nippostrongylus brasiliensis and Haemonchus contortus: Function of the excretory ampulla of the third-stage larva

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.

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The development of Haemonchus contortus in vitro: II. The effect of disulphide-reducing and sulphydryl-blocking reagents on the rate of development to the fourth-stage larvae

Parasitology ◽

10.1017/s0031182000077295 ◽

1970 ◽

Vol 60 (1) ◽

pp. 123-135 ◽

Cited By ~ 3

Author(s):

C. J. Mapes

Keyword(s):

Haemonchus Contortus ◽

Reduced Glutathione ◽

Stage Larva ◽

Fourth Stage ◽

Rate Of Development ◽

The Third ◽

Short Period ◽

Third Stage ◽

Before And After

Cysteine (20–100 mM) and reduced glutathione (20–80 mM) potentiated the development of the exsheathed third-stage larva of Haemonchus contortus to the fourth stage. The potentiating effect of cysteine was greatest during the short period before and after the exsheathment of the third-stage larva. Two hundred mM cysteine and 1 mM p–chloro-benzoate inhibited development. This inhibition was reversible. Ten mM iodoacetate and 0·5 and 5 mM n–ethyl-maleimide inhibited development of the larvae. The larvae appeared to be most susceptible to the inhibiting effects of these reagents during the period of development approaching the third moult. Development was either little affected or potentiated, when larvae were incubated with these reagents for short periods immediately after exsheathment.

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

Parasitology ◽

10.1017/s0031182000013354 ◽

1946 ◽

Vol 37 (3-4) ◽

pp. 192-201 ◽

Cited By ~ 13

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.

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