The Development of the Larval Pigment Patterns in Triturus Alpestris and Ambystoma Mexicanum

ISBN-13: 9783540516729 / Angielski / Miękka / 1990 / 101 str.

Hans-Henning Epperlein; Jan Lafberg

Opis

In the animal world, pigments and colour pigment patterns play an important role. Pigments in the epidermis offer protection against solar radiation, and the various colour patterns provide the animals with concealment, advertisement and disguise (Cott 1940). The study of pigment cells and colour patterns is a multidisciplinary research field which includes developmental biology (determination, differenti- ation, migration), genetics (phenotypic gene expression, colour mutants), cell biology (ultrastructure, organelles, cell surface), biochemistry (enzymes, metabo- lism), physiology (control of colour changes) and dermatology, as well as ecology and evolution. In the present study we investigate the development of two different amphibian larval pigment patterns. These patterns might serve as specific models for the arrangement of cells derived from the neural crest (NC), involving their migration, differentiation and interaction with each other and the embryonic environment. Because of the NC origin of pigment cells, we consider first some general aspects of NC development, before turning to pigment cells and specific problems in pigment pattern formation. The NC arises during neurulation, an early process in vertebrate embryoge- nesis. In amphibians, the crest lies on top of the neural tube as a flat epithelial sheet or strand of cells (Detwiler 1937; Schroeder 1970; L6fberg and Ahlfors 1978; Spieth and Keller 1984). Here the term 'crest' is much more appropriate than in birds or mammals (Newgreen and Erickson 1986), where the crest cells start to migrate before a true crest has formed.

Spis treści

1 Introduction.- 2 Materials and Methods.- 2.1 Embryos.- 2.2 Light Microscopy.- 2.3 Videomicrography.- 2.4 Transmission Electron Microscopy.- 2.5 Scanning Electron Microscopy.- 2.6 Dopa Reaction.- 2.7 Pterin Fluorescence.- 2.8 Staining with Alcian Blue.- 2.9 Immunohistochemistry.- 2.10 Developmental Protocols.- 2.11 Embryological Experiments.- 2.11.1 Removal of the Epidermis.- 2.11.2 Exchange of the Epidermis.- 2.11.3 Rotation of the Epidermis.- 2.11.4 Chromatophore Number.- 2.11.5 Pronephric Duct.- 2.11.6 Rotation of the Somites.- 2.11.7 Axolotl Embryo as Host.- 2.11.8 Triturus Embryo as Host.- 2.11.9 Younger Triturus Embryo as a Host.- 2.11.10 Microcarrier Experiments.- 2.11.11 Mesoderm.- 2.11.12 Heterotopic Transplantation of the Neural Crest.- 2.12 Tissue Culture.- 2.12.1 Neural Fold Explants.- 2.12.2 Epidermis and Neural Crest.- 3 Results.- 3.1 Fundamental Premises.- 3.2 Development of the Longitudinal Stripe Pattern in Triturus alpestris.- 3.2.1 Dispersion.- 3.2.2 Onset of Longitudinal Stripe Formation.- 3.2.3 Definite Longitudinal Stripe Pattern.- 3.3 Development of the Barred Pigment Pattern in Ambystoma mexicanum.- 3.3.1 Early Spreading.- 3.3.2 Dispersion.- 3.3.3 Definite Barred Pattern.- 3.4 Analysis of Factors and Mechanisms Governing Pigment Pattern Formation in Triturus alpestris.- 3.4.1 Pigment Cells.- 3.4.1.1 Segregation.- 3.4.1.2 Shape, Number and Behaviour.- 3.4.1.3 Cell Number and Pigment Pattern.- 3.4.2 Epidermis.- 3.4.2.1 Epidermis-Deprived Embryos and Epidermis-Crest Cultures.- 3.4.2.2 Heterotopic Exchange.- 3.4.2.3 Rotation.- 3.4.2.4 Subepidermal Extracellular Matrix.- 3.4.2.4.1 Electron Microscopic Investigations.- 3.4.2.4.2 Histochemical and Immunohistochemical Studies.- 3.4.3 Other Tissues.- 3.4.3.1 Pronephric Duct.- 3.4.3.2 Blood Vessels.- 3.4.3.3 Neural Tube, Somites.- 3.4.3.4 Mesoderm and Endoderm.- 3.4.3.5 Axolotl Embryo as Host.- 3.4.3.6 Younger Triturus Embryo as Host.- 3.5 Analysis of Factors and Mechanisms Governing Pigment Pattern Formation in Ambystoma mexicanum.- 3.5.1 Pigment Cells.- 3.5.1.1 Segregation.- 3.5.1.2 Cell Shape.- 3.5.1.3 Cell Number.- 3.5.2 Epidermis.- 3.5.2.1 Epidermis-Deprived Embryos.- 3.5.2.2 White Axolotl Embryos.- 3.5.2.3 Epidermal Implants.- 3.5.2.4 Microcarrier Experiments.- 3.5.3 Other Tissues.- 3.5.3.1 Blood Vessels.- 3.5.3.2 Neural Tube, Somites, Gut.- 3.5.3.3 Neural Crest at Heterotopic Sites.- 3.5.3.4 Triturus Embryo as Host.- 4 Discussion.- 4.1 Dopa Reaction and Pterin Fluorescence: Criticism of the Methods.- 4.2 Organization of the Neural Crest and Early Dispersion of Pigment Cells.- 4.3 Arrangement of Pigment Cells in the Trunk.- 4.3.1 Dispersion of Pigment Cells.- 4.3.2 Formation of Melanophore and Xanthophore Zones in Triturus alpestris.- 4.3.2.1 Cell Shape and Rearrangement of Chromatophores.- 4.3.2.2 Dorsal Stripe.- 4.3.2.3 Lateral Stripe.- 4.3.2.4 Arrangement of Melanophores and Xanthophores in Relation to Axial Cues.- 4.3.3 Bar Formation in Ambystoma mexicanum.- 4.4 Comparison of the Development of the Larval Pigment Pattern in Triturus alpestris and Ambystoma mexicanum.- 4.5 Conclusion and Perspectives.- 5 Summary.- Acknowledgements.- References.