Underwood H, Menaker M
Science. 1970 Jan 16;167(3916):298-301. doi: 10.1126/science.167.3916.298.
Blind house sparrows (150 birds) and normal ones (199 birds) were subjected to various photoperiodic treatments consisting of cycles of 12 hours light, 12 hours dark and 16 hours light, 8 hours dark at intensities ranging from 20 to 500 lux. The testicular, response of the blind birds was found to be indistinguishable from the response of normal birds under these conditions. The data show that a functional extraretinal photoreceptor exists in this species which is fully capable of mediating the gonadal response to photoperiodic stimuli.
对150只失明家雀和199只正常家雀进行了各种光周期处理，包括12小时光照、12小时黑暗以及16小时光照、8小时黑暗的周期，光照强度范围为20至500勒克斯。结果发现，在这些条件下，失明家雀的睾丸反应与正常家雀的反应没有区别。数据表明，该物种存在一种功能性的视网膜外光感受器，它完全能够介导性腺对光周期刺激的反应。
