Phasmid ultrastructure of an ascaridoid nematode Hysterothylacium auctum.
Here, for the first time in an ascaridoid (Hysterothylacium auctum), we present structural features of the phasmids, paired sense organs, positioned in a bilateral manner close to the point of the tail; the features were obtained using scanning and transmission electron microscopy. We found that each phasmid consists of a single ciliated dendritic process situated in a phasmidial canal surrounded by 2 supporting cells, a socket and a sheath cell. The socket cell contains clusters of electron-dense fibrous material in its apical region and covers the phasmidial canal along its whole length. The sheath cell is characterized by a well-developed endoplasmic reticulum. The phasmidial canal is lined with a thin layer of cuticle that becomes incomplete at the base of the ciliated dendritic process. In this region, the dendritic process consists primarily of a high number of microtubule singlets and some peripheral microtubule doublets. The base of the dendritic process, containing numerous striated rootlets, gives off a large number of fingerlike offshoots, villi, invading the surrounding sheath cell. The systematic significance and functional implication of the phasmid in nematodes are also discussed.
Fagerholm
Hans-Peter
HP
Laboratory of Aquatic Pathobiology, Department of Biology, Abo Akademi University, BioCity, Artillerigatan 6, FIN-20520 Abo/Turku, Finland. hafagerh@abo.fi
Brunanská
Magdaléna
M
Roepstorff
Allan
A
Eriksen
Lis
L
D000818:Animals; D017191:Ascaridida Infections / Q000469:parasitology / Q000662:veterinary*; D001199:Ascaridoidea / Q000648:ultrastructure*; D005260:Female; D005393:Fish Diseases / Q000469:parasitology*; D007422:Intestines / Q000469:parasitology; D008297:Male; D008854:Microscopy, Electron / Q000662:veterinary; D008855:Microscopy, Electron, Scanning / Q000662:veterinary; D010473:Perciformes / Q000469:parasitology*