Eighteen experiments examined the physical characteristics and physiological modulation of the ultrasound-eliciting property of female urine. Experiments 1 and 2 indicated that an excitatory factor exists in female urine and that male urine is essentially neutral with regard to ultrasound elicitation. Experiments 3, 4, and 5 indicated that the ultrasound-eliciting factor is relatively nonvolatile and heat resistant, although extreme heat will destroy its activity. The results of Experiments 6,7,8, 9, and 12 suggested a minor modulating effect of ovarian hormones upon ultrasound-eliciting potency; however, ovarian hormones accounted for only a small proportion of the variability between females and males. Adrenal hormones also appeared relatively unimportant (Experiment 13). Experiment 10 demonstrated that exogenous androgen suppresses female urinary ultrasound-eliciting activity; however, this effect may not be directly relevant to normal male-female differences in urinary potency. Castration of males in adulthood (Experiments 11 and 12) or on the day of birth (Experiment 15) did not improve the ability of their adult urine to elicit ultrasounds. Nor did administration of androgen to neonatal females suppress the ability of their adult urine to elicit ultrasounds (Experiment 14). Experiments 16,17, and 18 indicated that hypophysectomy eliminates the ultrasound-eliciting properties of female urine, which suggests that the dimorphism in ultrasound elicitation may be regulated by pituitary hormones.Male mice emit ultrasonic vocalizations male begins mounting the female, decline when courting and copulating with females, across intromissions, and cease altogether by The ultrasounds are most prominent during ejaculation. Whether subsequent ejaculainitial investigatory behavior and temporally tory sequences in a mating bout also contain correlate with male behaviors that indicate male ultrasounds is not known. Females, a high degree of sexual motivation (Sales, however, seldom emit ultrasounds during 1972). The ultrasounds continue after the male-female encounters (Whitney, Coble, Stockton, & Tilson, 1973). This investigation was supported by National Science , Sever , al indirect lines of evidence suggest Foundation Grant BNS77-15265, by National Insti-that male ultrasounds may serve a courtship tute of Mental Health Training Grant MH 11218, and function. In addition to the temporal corby Research Service Award P32 NS05259 from the relation of ultrasounds with male sexual National Institute of Neurological and Communicative arousal the motivation to pro duce ultra-Disorders and stroke. , .
