Syphacia muris: response to environmental stimuli when hatching in vitro.

It is known that several oxyurids have hatched in fluids without extra stimuli except digestive enzymes, whereas the eggs of several other nematodes require for hatching optimal temperature, pH, redox potential, and pCO₂ but no enzymes. Consequently, a study was carried out on the effect of external stimuli on hatching of the eggs of the oxyurid Syphacia muris.Eggs of S. muris, attached to pieces of transparent adhesive tape, proved themselves able to hatch in a PO₄-buffer to which only trypsin and bile had been added. Trypsin acted, like NaOH on other nematode eggs, by dissolving proteins from the surface of the eggshell. The addition of reducing agents, and to some extent CO₂, had a stimulating effect. Hatching began to occur at 19 C and at pH 3, although 41 C and pH 7 gave optimal results.The conclusion is that the eggs of S. muris react in the same way to the environment as those of Ascaris lumbricoides and other nematodes which hatch inside the hosts' intestinal tracts. S. muris eggs distinguish themselves, however, by being dependent on the environment to an appreciably lesser extent.This last characteristic makes it possible to use simple media for routine hatchings of these eggs, for instance, in disinfection tests.