Comparative Effects of Light Stimulation and Administration of Gonadotropic Hormones on Female Sparrows

Female sparrows (Passer domesticus) were subjected to increased daily periods of illumination at different times during the fall and winter. In every instance the effect upon the ovary was very slight. On the other hand, the ovaries respond to injections of gonadotropic hormones at any time during the sex cycle. The development approaches that attained at the height of the breeding season. The results indicate that it is not a refractoriness of the ovary which explains the non-effect of light during the fall and winter, but rather the failure of the anterior pituitary to release the essential hormones. Contrary to the situation in the male sparrow, the pituitary of the female responds little to light stimulation