mesectoderm anlage AMesEc FBbt:00000109 Contiguous region of early embryonic cells of the ectoderm anlage that forms a single-cell border between the anlagen of the mesoderm and ventral ectoderm (Campos-Ortega and Hartenstein, 1997; Stathopoulos and Newcomb, 2020). As the mesoderm invaginates and the ventral furrow closes, the two rows of cells come together to form the mesectoderm at the ventral midline of the embryo (Campos-Ortega and Hartenstein, 1997). fly_anatomy.ontology mesectoderm ISN FBbt:00000109 Drosophila developmental tissue