Abstract
Gene mutations and transgenic animals are used to specify gene functions, however, genes have multiple effects and even albinism results not just in fur color phenomena but also in structural changes of brain networks. We were interested if the color mutations described for the American mink (Neovison vison var. spec.) induce changes in the olfactory bulb. Therefore we investigated different coat color varieties of the American mink: “standard” (Neovison vison var. atratus), “silverblue” (Neovison vison var. glaucus), “pastel” (Neovison vison var. suffuscus), “wild” (Neovison vison var. carinum) for size and composition of
the olfactory bulb. Following histological processing always the right olfactory bulb of adult males and females was analyzed using a morphometric system and weight/volume correction factors. The results reveal, that in all color-varieties of the American mink, the absolute size of the olfactory bulb is statistically significantly different between the sexes, with higher values in males, whereas
the size variations within sexes among the color-varieties are small. Analyzing the composition of the olfactory bulb, the neural structure displays the typical appearance with the major portions being fila, external plexiform and granule cell layers. Sexual differences exist in all color-varieties with the females having a thicker granule cell and thinner fila layer compared to males; however, within sexes among the color-varieties, only slight alterations in the composition were observed, which do not show a systematic pattern of changes and no ranking among the color-varieties is obvious. This indicates that the olfactory bulb, probably due to its phylogenetic old age and emphasizing its
functional importance, is a very stable structure and less
susceptible to gene alterations. Acknowledgements: DFG (SFB 509 /TP C4) FORUM F208/00 M122/13 (2000).
