Comparative morpho-anatomical studies of the female gonoduct within the Pratylenchidae (Nematoda : Tylenchina)

The cellular morphology of the gonoduct of six Pratylenchus species, three Pratylenchoides species, Radopholus similis, Zygorylenchus guevarai, Hirschmanniella loofi and Nacobbus aberrans was revealed by dissection and light microscopy. Except for Nacobbus aberrans, all studied species show an overall similarity in gonoduct construction, i.e., an ovary often ending with a ring of cells, an oviduct formed from two rows of four cells and a 12-celled spermatheca followed by a tricolumella containing 16-24 cells. Pratylenchoides magnicauda and Z guevarai did not diverge from the other Pratylenchidae in this respect, although their gonoduct differs from that of Amplimerlinius and Meloidogyne, both formerly postulated as related genera. The spermatheca structure observed in N. aberrans has not been reported elsewhere in the Nematoda, although the uterus is similar to that reported within the Heteroderinae and Meloidogyninae and the uterus comprises more than 300 cells, enlarging from a tricolumella to a polycolumella. Transmission electron microscopy of Z guevarai revealed details of the cytoplasmatic contact between epithelial cells and the germ cells; a finger-like ovarian wall cell extension was found penetrating the oocyte. The oviduct lacks a preformed lumen and comprises eight cells with highly plicated cell membranes. The spermatheca is constructed from flattened wall cells and is followed by columnar uterus cells where evidence of eggshell formation was demonstrated