Studies on the accessory reproductive organs in the drake

The effects of androgen on the ejaculatory groove region (EGA) of the drake were investigated. Testosterone propionate was injected into the juvenile male duckling and prepuberal castrate male. The EGR developed as a result of androgen administration, showed the characteristic appearance of EGR of adult drakes. The oozing of the fluid from the ejaculatory groove region (EGR-fluid) was observed 9 to 12 days after injection and the characteristics of the fluid were similar to those of normal drakes. Some secondary sexual organs, that is, the penis, vas deferens and vascular body were also developed by androgen injection to the same extent as those of normal drakes. Castration of adult drakes resulted in the involution of the secondary sexual organs including the EGR and the volume of EGR-fluid decreased with the lapse of days and no oozing of the fluid was observed one month after castration. In view of these results and the function of EGR, the EGR should be considered an accessory reproductive organ of the drake.