Aims and objectives

This exercise is designed to demonstrate:

1. The external and internal morphology of the adult stage of the nematode parasite Heligmosomoides polygyrus.

2. The mating behaviour of the adult worms.

3. The distribution of worms in the small intestine and the selection of a preferred site.

Introduction

Intestinal nematode parasites are very common in mammalian hosts and are responsible for human disease as well as for losses to the agricultural industries through their effects on domestic animals. H. polygyrus (Fig. 1.15.1) is an intestinal nematode parasite of mice that is very easy to maintain in the laboratory and provides convenient material to demonstrate some of the adaptations that have evolved in nematodes for survival in their hosts.

Unfortunately, this parasite has been the subject of a longstanding taxonomic debate as to the most appropriate name for the species. These problems are discussed by Behnke et al. (1991) and the reader is referred to this publication for further details. The approach used here is that the alternative name for the species, Nematospiroides dubius, is no longer used. H. polygyrus bakeri is the strain maintained in domestic/laboratory mice, Mus musculus. In Europe, however, wild field or wood mice, Apodemus sylvaticus, carry the subspecies called H.p. polygyrus and voles, Clethrionomys glareolus, H. glareoli. All of these, if available, can provide useful teaching material. This protocol is based on the laboratory passaged subspecies H. polygyrus bakeri.