STRUCTURE OF THE FEMALE REPRODUCTIVE-SYSTEM OF XIPHINEMA-AMERICANUM (NEMATODA, LONGIDORIDAE)

The female reproductive system of Xiphinema americanum differs from th at of other Xiphinema species in several respects. The ovary has branc hed oocytes surrounded by epithelial wall cells in which symbiotic bac teria are embedded. The oviduct has a long pars dilatata which is not clearly separated from the slender part; its wall is extensively folde d and extendible. The sphincter between oviduct and uterus has a sinuo us lumen and 'internal musculature'. The uterus is extremely short and has a folded wall; the two uteri constitute together an extendible ov ejector. Shortening of the uterus is considered to be an evolutionary trend in the X. americanum-group. (C) Orstom/Elsevier, Paris.