{'fraction_non_alphanumeric': 0.01866151866151866, 'fraction_numerical': 0.003861003861003861, 'mean_word_length': 5.67381974248927, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Lineage analysis of early neural plate cells: cells with purely neuronal fate coexist with bipotential neuroglial progenitors.

To investigate the lineage relationships of neurons and astroglial cells early in central nervous system development, we have analyzed the progeny of neural plate cells in an amphibian embryo (Pleurodeles waltl). A fluorescent tracer, lysinated rhodamine-dextran, was iontophoretically injected into individual precursor cells in various areas of the early neural plate. The phenotypes of clonally related cells were identified in the hindbrain and spinal cord by morphological and immunohistochemical criteria 12 days later, at larval stages. We found that the large majority of clones (83%) contained both neurons and astroglial cells, whereas the remainder (17%) were homogeneous and were only composed of neurons. We never observed purely astroglial clones. These results clearly demonstrate the predominance of bipotential progenitors in the neural plate. Interestingly, the progenitors with a restricted neuronal fate were always located along the intermediate axes of the neural plate, while mixed progenitors were found in all areas examined. The analysis of migratory paths has shown that sister cells first migrated together along radial pathways without dispersion along the rostrocaudal axis. From larval stages, some neurons migrated away from the original clonal cohort along dorsoventral and ventrodorsal tangential routes, but only after they had reached the border between the intermediate and marginal zones.