Distribution of different regions of cardiac neural crest in the extrinsicand the intrinsic cardiac nervous system

In this study we focused upon whether different levels of postotic neural c rest as well as the right and left cardiac neural crest show a segmented or mixed distribution in the extrinsic and intrinsic cardiac nervous system. Different parts of the postotic neural crest were labeled by heterospecific replacement of chick neural tube by its quail counterpart. Quail-chick chi meras (n = 21) were immunohistochemically evaluated at stage HH28+, HH29+, and between HH34-37. In another set of embryos, different regions of cardia c neural crest were tagged with a retrovirus containing the LacZ reporter g ene and evaluated between HH35-37 (n = 13). The results show a difference i n distribution between the right- and left-sided cardiac neural crest cells at the arterial pole and ventral cardiac plexus. In the dorsal cardiac ple xus, the right and left cardiac neural crest cells mix. In general, the ext rinsic and intrinsic cardiac nerves receive a lower contribution fu om the right cardiac neural crest compared with the left cardiac neural crest. The right-sided neural crest from the level of somite 1 seeds only the cranial part of the vagal nerve and the ventral cardiac plexus. Furthermore, the r esults show a nonsegmented overlapping contribution of neural crest origina ting from S1 to S3 to the Schwann cells of the cranial and recurrent nerves and the intrinsic cardiac plexus. Also the Schwann cells along the distal intestinal part of the vagal nerve are derived exclusively from the cardiac neural, crest region. These findings and the smaller contribution of the m ore cranially emanating cardiac neural crest to the dorsal cardiac plexus c ompared with more caudal cardiac neural crest levels, suggests an initial s egmented distribution of cardiac neural crest cells in the circumpharyngeal region, followed by longitudinal migration along the vagal nerve during la ter stages. (C) 2000 Wiley-Liss, Inc.