SCOLEX GLANDS ASSOCIATED WITH THE ROSTELLA IN 3 SPECIES OF THE DILEPIDIDAE (CESTODA, CYCLOPHYLLIDEA)

The microanatomy, fine structure and cytochemistry of scolex glands of Vitta riparia, Angularella beema and Trichocephaloidis megalocephala are examined by light and electron microscopy. Cytochemical tests incl ude PAS, mercury bromphenol blue and performic acid-alcian blue for li ght microscopy and periodic acid-thiocarbohydrazide-OsO4 for electron microscopy. The scolex glands are organized in two spatially isolated syncytia, one located in the rostellum, the other in the rostellar sac . The cytoplasm of the gland syncytia is characterized by a high affin ity for haematoxylin. Cytochemical tests indicate the presence of mode rate amounts of glycoprotein in the glands. A specialized type of secr etion-dark oval or ovoid bodies with diameter 0.3-0.5 mu m are observe d by EM in both the rostellum grands and the rostellar-sac glands of V . riparia and T. megalocephala, and in the rostellar-sac gland of A. b eema. The rostellum gland of A. beema produces larger dark oval bodies measuring up to 0.9 mu m. Lipid droplets are also observed in the gla ndular cytoplasm. Some tegumental cytons containing discoid bodies are found between the glandular perikarya. The glandular products and the lipid droplets are secreted via the rostellar tegument. (C) 1997 Publ ished by Elsevier Science Ltd on behalf of The Royal Swedish Academy o f Sciences.