EYE AND GONAD - ROLE IN THE DUAL-OSCILLATOR CIRCADIAN SYSTEM OF FEMALE JAPANESE-QUAIL

Experiments were conducted to determine the anatomic and physiological basis of the dual-oscillator circadian system of female Japanese quai l. After blocking of ocular light perception by eye-patching, the circ adian body temperature rhythm dissociates into two circadian component s in continuous lighting (LL). One component free runs with a period s ignificantly shorter than 24 h [mean period (<(tau)over bar>) = 22.7 h ] and is driven by an ocular pacemaker, whereas the other component fr ee runs with a period significantly longer than 24 h (<(tau)over bar> = 26.3 h). The long free-running rhythm is driven by the same circadia n clock that drives the circadian rhythm of ovulation. The expression of the long free-running rhythm in LL depends on the presence of the o vary: body temperature rhythmicity is abolished by ovariectomy. The tw o free-running oscillators in eye-patched birds showed evidence of mut ual interaction. Significantly, the phase relationships that occur as the two oscillators interact can determine whether or not ovulation oc curs. The results are discussed in terms of an ''internal coincidence' ' mechanism for photoperiodic time measurement.