Induction of Pseudopregnancy in the Golden Hamster

In the hamster, unlike the rat in which pseudopregnancy is induced with ease, past attempts to induce pseudopregnancy by mechanical vaginal-cervical stimulation have been unsuccessful (Carlson & DeFeo, 1953; DeFeo, 1966.) Pseudopregnancy in this species is usually induced by mating an oestrous female with a vasectomized buck overnight. The wide use of the hamster, however, in ovarian and reproductive studies indicated to us that an alternative means of inducing pseudopregnancy would prove of practical experimental value. The present study reports various attempts to induce pseudopregnancy mechanically and compares the results with those obtained by sterile matings. Mature virgin females, 3 to 6 months old, weighing 100 to 160 g were used. They were housed in groups in plastic cages (16 × 12×6 in.) and placed singly in cages for one oestrous cycle before stimulation