LIGHT: EVIDENCE FOR ITS DIRECT EFFECT ON HYPOTHALAMIC NEURONS

Continuous light impinging on the suprachiasmatic region of enucleate rats resulted in a constant estrous-like vaginal cycle. The lowest precentage of cornified cells was obtained from exposure of the arcuate or mammillary neurons to light. Ovarian and pituitary weight increased significantly after exposure of the arcuate region to continuous light.