Long-term effects of diencephalic lesions on the ovary of the hen

¹ Agricultural Research Service, U.S. Department of Agriculture, Beltsville, Maryland

Small lesions produced electrolytically in the median diencephalon of actively ovulating hens caused most of them to cease ovulation regardless of the site of lesions. The duration of the nonovulating period thus induced, however, tended to vary with position of the lesions. When in the preoptic hypothalamus, supraoptico-hypophyseal tract, or dorsocaudal thalamus, the mean periods of interruption were about twice that found when lesions were in the central diencephalon. Considerable variability was encountered, however. A possible explanation is offered for the differing rates of functional recovery which occur following the placement of lesions.