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The reproductive system of female prairie voles remains quiescent in the absence of stimulation from males; however, chemosignals from males are capable of at least partially activating female reproduction. In other species, the vomeronasal system mediates some of the reproductive responses of females to males. We found that surgical removal of the vomeronasal organ (VNX) from adult female prairie voles impeded reproductive activation in response to pairing with stud males: ovarian and uterine weights of VNX females paired with stud males for 24 or 60 hours were significantly less than those of normal (NORMAL) or sham-operated (SHAM) females. Furthermore, 8 of 9 NORMAL, 10 of 13 SHAM, but only 4 of 9 VNX females paired with stud males for 60 hours mated. VNX females, however, were still able to use chemosensory cues to locate food. Behavioral observations of females encountering stud males were similar for VNX, SHAM and NORMAL females. We conclude that vomeronasal chemoreception may be a primary component of reproductive activation in female prairie voles, presumably by mediating neuroendocrine responses to chemosignals.

Detection of reproductive status from chemical signals at sandbathing loci was examined in Merriam's kangaroo rat. Castrated and intact males were attracted similarly to the sandbathing loci of four classes of scent donors: intact males, castrated males, estrous females, and nonestrous females. This suggested that reproductive status was not communicated to males at sandbathing loci. In a control test, castrated males were attracted to disturbed sand that contained no olfactory cues whereas intact males were not. Castration caused a significant decrease in the size of a specialized sebaceous gland on the dorsum. Castration did not affect total pelage lipids, however, indicating that lipid-producing cells have a baseline level of secretion that is necessary for pelage maintenance.