Spicule Structure in Some Heterodera Spp

Observations with the scanning electron microscope on spicule structure of eleven species of Heterodera confirmed that the spicule tips in species of H. (Heterodera) were basically bifid whereas those of H. (Globodera) had single points. In all the species two small pores were located close to the tip of each spicule. Sections through the spicules of H. rostochiensis observed with the transmission electron microscope showed that they contained a large nerve which tapered towards the spicule tip, where two dendritic elements were associated with the pores. The shape of the spicule blades, which have incurved, interlocking wings, ensures an enclosed, tubular structure through which sperm can he transferred when the spicules are protruded and inserted into the female reproductive tract. In mating, the spicules may have a sensory function.