Figure 1.

Possible reproductive pathways of melatonin and clock genes. Melatonin and clock genes are involved in optimal reproductive performance. Their rhythms are controlled by an endogenous molecular clock within the suprachiasmatic nucleus in the hypothalamus, which is entrained by the light/dark cycle. Both melatonin and clock genes exist in ovarian granulosa cells. Disruption of melatonin and clock genes rhythms interferes with ovarian steroidogenesis and reproductive function. SCN = suprachiasmatic nucleus, RHT = retinal-hypothalamic tract.