This pineal gland does not mediate phase shifts in the disc shedding rhythm of the rat retina.

Albino rats were subjected to pinealectomy, superior cervical ganglionectomy, or the appropriate sham preparation and were placed in lighting conditions so that light onset was advanced by 10 hr. After 6 days of this regimen, all animals exhibited a complete shift in their outer segment disc shedding rhythm, indicating that the pineal gland is not a factor in mediating such a shift.