Extraretinal Photocontrol of Oviposition in Pinealectomized Domestic Fowl

Abstract

Oviposition response to photo-period was studied in normal, pinealecto-mized, enucleated, and enucleated-pinealectomized chickens. Oviposition pattern in all of the treatments responded to reversal and shifts in the light-dark cycle. Hooded enucleated and enucleated-pinealectomized birds showed the same oviposition response to light reversal as the birds with eyes intact. Oviposition pattern, though entrained by the photoperiod, indicated a definite pattern within the photoperiod. Some birds in all of the treatments exhibited a free-running circadian pattern of oviposition in continuous light. These data demonstrate that photocontrol of oviposition in the chicken occurs without eyes or pineal and that the pineal is not necessary for free-running circadian pattern of oviposition.