THE EMBRYONIC CENTRAL NERVOUS SYSTEM LINEAGES OF DROSOPHILA MELANOGASTER. II. NEUROBLAST LINEAGES DERIVED FROM THE DORSAL PART OF THE NEUROECTODERM

摘要: Central nervous system development in Drosophila starts with the delamination from neuroectoderm of about 30 neuroblasts (NBs) per hemisegment. Understanding mechanisms leading to specification individual NBs and their progeny requires identification lineages. Here we describe 17 embryonic NB lineages derived ventral half assign these identified medial intermediate NBs. The are composed interneurons (NB 1-2, 2-1, MP2, 4-1, 5-1, 5-3, 6-1, 6-2, 7-2), motoneurons 3-1, 3-2, 4-2, 5-2, 7-1, 7-3), or interneurons, motoneurons, glial cells 1-1 2-2). 1-1, 2-2, 3-1 form segment-specific Neuroectodermal progenitors forming 7-3 divide while still ectoderm give rise an additional epidermoblast. Expression segmentation genes is not lineal clones 1-2 (engrailed), 7-1 (even-skipped), (gooseberry-proximal). timing for as well number strictly invariant. produce 200 neurons only three cells, corresponding 70% estimated total 10% thoracic abdominal Previously neural cell types were linked particular introduce a systematic terminology nerve cord neurons. wild-type provide foundation analysis mutants, expression patterns, experimental manipulations.