title: Vomeronasal organ removal blocks pheromonal induction of estrus in gray short-tailed opossums (Monodelphis domestica).
abstract: Estrus is induced in female gray short-tailed opossums (Monodelphis domestica) by exposure to male chemical signals (pheromones). Isolated females remain anestrous, but direct exposure to a male or his scent-marked cage induces estrus within 4-6 days. The objective of this study was to investigate the importance of the vomeronasal organ in detection of and response to estrus-inducing pheromones. The vomeronasal organ was surgically removed through the palate from 8 females (VNX); 5 females (SHAM) underwent sham surgeries in which the vomeronasal organ was exposed but not removed. After a 10-day recovery period, females were placed into male scent-marked cages. Body weight and urogenital sinus cytology were monitored throughout the experiment. All females were anesthetized and perfused with 4% paraformaldehyde 12-13 days after initial pheromone exposure. Vomeronasal organ ablation was evaluated histologically in decalcified snouts. In addition, deafferentation of the accessory olfactory bulb was confirmed by use of a lectin stain specific for the vomeronasal nerve and the glomerular layer of the bulb. All females classified as completely VNX (n = 5) remained anestrous throughout the pheromonal exposure. Incompletely VNX females (n = 2) and all SHAM animals exhibited estrus within 7 days of pheromone stimulation. At perfusion, the mean uterine weight (280.71 +/- 95.6 mg/85 g BW) of SHAM females was greater (p < 0.05) than that of unresponsive, VNX females (133.33 +/- 31.14 mg/85 g). This study demonstrates that the vomeronasal organ is an essential component for transduction of male pheromones required for induction of estrus in a marsupial species.
authors.affiliation: Department of Zoology, Ohio State University, Columbus 43210, USA.
authors.forename: L M
authors.initials: LM
authors.lastname: Jackson
authors.forename: J D
authors.initials: JD
authors.lastname: Harder
mesh_terms: D000818:Animals; D003714:Denervation; D004971:Estrus; D005260:Female; D008297:Male; D009300:Nasal Septum; D009830:Olfactory Bulb / Q000033:anatomy & histology / Q000502:physiology / Q000601:surgery; D009833:Olfactory Pathways / Q000502:physiology* / Q000601:surgery; D009893:Opossums / Q000502:physiology*; D009929:Organ Size; D010675:Pheromones / Q000494:pharmacology*; D014599:Uterus / Q000033:anatomy & histology
chemical_list: D010675:Pheromones