Osmoregulation in the Parasitic Nematode Pseudoterranova Decipiens Available to Purchase

When subjected to hyper-or hypo-osmotic stress at 5°C for 24h, third-stage larvae of the parasitic nematode Pseudoterranova decipiens do not exhibit changes in mass or in the osmotic pressure of the pseudocoelomic fluid. Immersion in solutions containing ³H₂O demonstrates that exchange with the water in the pseudocoelomic fluid is substantially complete within 24h. Sacs composed of cylinders of body wall without the intestine and pseudocoelomic fluid do not gain weight when immersed for 24h in hypotonic medium. Metabolic poisons abolish the ability of whole worms and sacs to maintain their weight when immersed in hypotonic media. These observations support the conclusion that the nematode is capable of at least short-term osmoregulation and that the site of osmoregulation is the body wall. The observations that more fluid is passed from the anus in some hypo-osmotically stressed worms and that worms ligatured at the tail exhibit a small increase in mass when exposed to hypo-osmotic conditions may indicate that the intestine plays a minor and subsidiary role in osmoregulation.