In the female the gonad is complex as in flatworms, composed of a germary for the formation of the eggs, and a vitellary, much more conspicuous and alone figured (ov), consisting of a definite number of large nucleated cells for the nourishment of the eggs.
- Rotifera are unisexual, with the sexes dimorphic. The ovary is, as in many Platyhelminthes, duplex; one part, the germary, being an organ for the production by cell multiplication of the germ-cells or eggs.
In Asplanchnaceae the germary is median, continuous at the distal end with the middle of the transverse horseshoe-shaped vitellary.
In Bdelloidaceae and Seisonaceae the whole organ is paired, the germary proximal, the vitellary next the cloaca.
Germary and ovary paired; oviduct absent; young viviparous.
Trophi virgate exsertile; germary paired; genito-urinary cloaca opening above the neck in the male, subapically in the female.