Gene Rearrangement, delta-Chain T-Cell Antigen Receptor; Immune System/growth & development; Receptors, Antigen, T-Cell, gamma-delta/genetics; Ambystoma mexicanum; Amino Acid Sequence; Animals; Base Sequence; Cell Differentiation; DNA Nucleotidylexotransferase/genetics; GATA3 Transcription Factor/genetics; Gene Expression; Homeodomain Proteins/genetics; Ikaros Transcription Factor/genetics; Immune System/immunology; Immune System/metabolism; In Situ Hybridization; Intestinal Mucosa/metabolism; Intestines/growth & development; Intestines/immunology; Larva/growth & development; Larva/immunology; Larva/metabolism; Liver/growth & development; Liver/immunology; Liver/metabolism; Molecular Sequence Data; Receptors, Antigen, T-Cell, alpha-beta/genetics; Receptors, Antigen, T-Cell, gamma-delta/analysis; Receptors, Antigen, T-Cell, gamma-delta/immunology; Sequence Alignment; Skin/growth & development; Skin/immunology; Skin/metabolism; Spleen/growth & development; Spleen/immunology; Spleen/metabolism; T-Lymphocytes/cytology; T-Lymphocytes/immunology; T-Lymphocytes/metabolism; Thymus Gland/growth & development; Thymus Gland/immunology; Thymus Gland/metabolism