In this paper the authors give an anatomical and histological analysis of the genital duct in mature and immature females of Pomacea canaliculata (Lamarck, 1822). Anatomically, the vagina has an equal dimension in its extension, varying in form and volume, according to the maturation period. In the immaturity, it has a smaller diameter and volume. In the maturity, the vagina increases in volume, having the aspect of a tumescent organ, and in certain specimens shows an albuminous pink thread in its lumen. Histologically, the calcigenic activity of the gland is evidentiated by the presence of an amorphous and basophilic mass, without nuclear material. This material has a fragmented aspect in the vagina lumen that reacts positively in van Kossa's coloured preparations for calcareous salts.