Bidder’s organ has been described as a rudimentary ovary-like structure (Tanimura and Iwasawa, 1992; Spengel, 1876). The literature refers to Bidder’s organ as a structure exclusive for male bufonids and it has been used as a diagnostic character for this family (Duellman and Trueb, 1994). Some authors reported that if the testis is removed the Bidder’s organ develops into a functional ovary, and that this event represents a reproductive strategy (Tanimura and Iwasawa, 1986, 1987). Farias et al. (2002) investigated the Bidder’s organ of male Bufo ictericus, using routine and histochemical techniques in light microscopy and transmission electron microscopy. They concluded that the Bidder’s organs are provided with a structural apparatus that is able to produce sexual cells; then, it is not appropriate to designate the Bidder’s organ as a rudimentary ovary.
In this study, we used the female of Bufo ictericus to ascertain if the Bidder’s organ also occurs in female members of the Bufonidae.