Freshly prepared C. sinensis adult worms were washed with phosphate buffer solution (PBS, 20 mM, pH 7.4) and then were fixed with 4% paraformaldehyde. The worms were dehydrated by a graded ethanol series, embedded in paraffin blocks and stored in a desiccator until use. Sections (4 μm thickness) were mounted on slide glasses, deparaffinized, rehydrated and rinsed with PBS. The slides were incubated with rat anti-CsGRN or rat normal sera (1:50 dilutions) in PBS at room temperature for 2 h and then were washed with PBS three times. After incubation with Cy™3-conjugated anti-rat IgG (1:400 dilutions; Proteintech Group, Chicago, USA) for 2 h, the slides were washed with PBS three times and were observed under a light/fluorescence microscope (Olympus BX63, Hatagaya, Japan).