ULTRASTRUCTURE OF THE INTESTINE OF THE BACTERIOPHAGOUS NEMATODES CAENORHABDITIS-ELEGANS, PANAGROLAIMUS SUPERBUS AND ACROBELOIDES MAXIMUS (NEMATODA, RHABDITIDA)

The intestine of the three free-living rhabditid nematodes Caenorhabdi tis elegans, Panagrolaimus superbus and Acrobeloides maximus was studi ed using transmission electron microscopy of sections made at three lo cations along the intestine. Between the three nematode species, ultra structural differences in cellular components are minor. However, two cell types present in all three nematode species are positioned differ ently along the intestinal tract. Furthermore, two different types of secretions into the intestinal lumen were identified, one only at the anterior intestine, the second present along the entire length of the intestinal lumen. F-actin staining of fifteen whole-mount nematodes re vealed the presence of a well developed, cross-shaped intestinal muscl e, only present in Cephalobid species.