Triple selected polyA RNA for liver, kidney, ovary, testis, was obtained from Ambion (Austin, TX). Total RNA was obtained form Ambion for hypothalamus samples. All RNA samples had an agilent ratio greater than 1 indicating that degradation had not occurred. All RNA samples were prepared from a pool of 10 different animals. The total RNA samples were labeled for hybridization onto the microarray according to affymetrix protocols listed at: http://keck.med.yale.edu/affymetrix/protocols Keywords = Sex Specific Transcription, Mouse, Affymetrix, Healthy Mammalian Tissue