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

Abstract

SUMMARYThe ultrastructure of the body wall of the third-stage larva ofHaemonckus placeiwas 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.