Cytochemical and developemental studies on the color pattern formation

点击翻译按钮获取中文摘要

Color pattern of vertebrates is determined by specific expression of pigment cells in specific regions. Factors that control pigment cell differentiation and morphogenesis were examined using the cells of Oryzias latipes and Xenopus laevis. N-CAM and N-cadherin were found on cellular surface of differentiated xanthophores of both species and in leucophores of Oryzias while melanophores and iridophores did not express these molecules. Key molecules that guarantee attachment between the different types of cells to form tha chromatophore unit in vivo may be different from these CAMs and remain to be identified. The effort to improve antigen preservation and resolution in immunoelectromicroscopy is now being made. Differentiation of neural crest cells of Xenopus in culture can be controlled in some extent ; it is now able to induce or suppress melanophore differentiation but we still do not know the efficient way to induce the other types of pigment cells. N-cadherin (135 kd and 112 kd) is expressed in neural tube of Xenopus embryos (st.22) and in the chromatoblast (melanoblast) of later stage but gradually diminishes with the progress of melanophore differentiation. Regarding intrinsic factors, microtubules and vimentin are important to maitain cell morphology in Oryzias while in Xenopus and Rana melanophores, involvement of actin and myosin system is clearly shown. Further study onthe shift in cytoskeletal architecture during the development, i.e.migratory to sedentary state, and in the course of chromatophore unit formation during metamorphosis in amphibians should be carried out. In iridophores, the form of purine platelets is directly related whether the cell takes bipolar or flat, asymmetric form.