ALTERATIONS IN INCIDENCE OF MATING AND COPULATION-INDUCED OVULATION AFTER OLFACTORY BULB ABLATION IN FEMALE RATS

Intact control and sham-operated rats, when given sodium pentobarbitone at 13.30 h on the day of pro-oestrus, mated (controls, 10/12; shamoperated, 13/15) that night and underwent copulation-induced ovulation. However, after removal of the olfactory bulbs only 13 out of 23 pentobarbitone-blocked rats mated. Of the mated animals only six ovulated as compared with ten in the unoperated group and ten in the sham-operated group. The incidence of ovulation in all non-mated animals was low. In addition, the bulbectomized, mated animals which ovulated shed significantly fewer ova than did intact controls and sham-operated rats (6·8 as compared with 11·3 and 13·4, respectively). The incidence of mating in bulbectomized animals was also lower than in sham-operated animals when pentobarbitone was not given (8/16 and 8/11, respectively). Ovulation was essentially complete in all groups except in bulbectomized, mated rats which shed significantly fewer ova. It is suggested that olfactory inputs are important in mediating copulation-induced ovulation in the pentobarbitone-blocked rat and that copulation in the absence of olfactory inputs interferes in some way with the normal sequence of secretion of ovulatory hormone(s) in the non-blocked rat.