Ultrastructure of the trophosome, a food-storage organ in Gastromermis boophthorae (Nematoda: Mermithidae)

The ultrastructure of the trophosome of Gastromermis boophthorae (Welch & Rubzov, 1965) is described at selected points in the life cycle of this mermithid nematode. The trophosome is grossly modified for the assimilation and storage of nutrients, and comparison is made with a generalised nematode intestine, with which it may be homologous. At its maximum development the trophosome is a solid syncytial cylinder which almost fills the body cavity of the nematode. Internally it is packed with nutrient reserves, whilst the outer cytoplasmic layer exhibits features indicative of transport functions. The trophosome is linked to the hypodermis of the body wall by radially-orientated cytoplasmic bridges, and the possible significance of this arrangement is discussed in relation to the nutritional function of the trophosome.