Body and organ mass in agouti and non-agouti deer mice (Peromyscus maniculatus)

Body, adrenal, brain, heart, liver, kidney, spleen and testis masses were d etermined for agouti and non-agouti deer mice (Peromyscus maniculatus graci lis) of both sexes. Body mass was highest for non-agouti females and lowest for agouti females; and sex differences in body mass were significant for agouti, but not non-agouti, deer mice. Adrenal, brain and liver masses were similar between color morphs; heart mass-was greater in agouti males; and kidney, spleen and testis masses were all significantly greater for non-ago uti deer mice. Splenomegaly in non-agouti deer mice was prominent, as splee ns of non-agouti deer mice were 50% larger than those of agouti animals. Se x differences varied across organs and color morphs. For both color morphs, males had heavier adrenals and brains, whereas females had heavier livers and spleens. Kidney and heart mass was greater for female non-agouti deer m ice, but for agouti animals, heart mass was greater in males and kidney mas s differed little between the sexes. For both color morphs, testes and sple en mass was altered by photoperiod in 72 deer mice housed under short- or l ong-day conditions and the effect was stronger in non-agouti animals. This is the first report of splenomegaly and sex-specific body mass differences associated with the non-agouti allele. (C) 2001 Elsevier Science Inc. All r ights reserved.