The fine structure of adult Onchocerca volvulus. III. The cuticle, the interchordal hypodermis and the muscle cells of the female worm.

The morphology of the cuticle, the interchordal hypodermis and the muscle cells of three mature but not full-grown worms, one worm less than five years old, two worms at least five years old and seven worms of unknown age are described. The cuticle in the anterior region is very similar to that of the male worm, however, in the midbody region the cuticular structure is more simple. The length of the folds of the surface membrane and the thickness of the coat vary considerably. The outer surface of the hypodermis is increased by lamellae, the inner surface by a labyrinthine system of folds. The structure of the muscle cells is simpler than in the male worm: degenerative alterations are found frequently comprising reduction of the afibrillar portion, separation of the filaments from the septa, disintegration of the filaments, and separation of the plasma from the laminae and finally total disintegration of the cell, leaving the empty laminal coverings behind.