TOXOCARA-CANIS (NEMATODA, ASCARIDAE) - THE FINE-STRUCTURE OF THE OVIDUCT, OVIDUCT-UTERINE JUNCTION AND UTERUS

The fine structure of the oviduct, oviduct-uterine junction and uterus of the nematode Toxocara canis (Werner, 1782) is described. Columnar- type epithelioid cells with numerous microvilli at the apical membrane border the oviduct lumen. Many electron dense secretory products are present in these cells. The cells lining the oviduct-uterine junction have no microvilli. They are coated with an electron-dense layer and c ontain numerous membrane-bound dense material containing bodies. Exter nally, the cells are surrounded by a basal lamina and muscle cells. Th e epithelial cells lining the greater part of the paired uteri appear to be rather flat. The oocytes inside the oviduct are covered with a d ense thick plasma membrane and contain lipid droplets, dense granules and glycogen. The morphology of the oocytes before the fertilization i nside the oviduct-uterine junction resembles that of the oocyte in the oviduct. After the fertilization the egg shell formation takes place. The egg shell of T. canis is composed of four layers: uterine, vitell ine, middle chitinous and inner layer. The differences between the fin e structure of the egg shell of T. canis and other related nematodes a re discussed.