In vivo and in vitro development of somatostatin-like-immunoreactivity in the peripheral nervous system of quail embryos.

The appearance and development of somatostatin-like immunoreactivity (SLI) in the peripheral nervous system of quail embryos were studied using radioimmunoanalysis and immunocytochemistry. In vivo, no SLI is observed in neural crest cells before or during migration. SLI appears between days 3 and 4 of incubation in sympathetic ganglia, immediately following ganglion formation, and between days 4 and 5 of incubation in the adrenal gland, soon after the adrenal gland primordium first appears. The development of SLI in the adrenal gland differs from that in the sympathetic ganglia. While in the former the amount of SLI and the number of SLI-containing cells increase as the embryo ages, in the sympathetic ganglia the amount of SLI and the percentage of SLI-containing cells decrease. When migrating neural crest cells are obtained from the sclerotomal part of 3-day embryos and grown in culture, they first display SLI after 48 hr, and the amount of SLI increases thereafter. When the sympathoadrenal precursors are removed at 4 days of incubation and grown in vitro, SLI appears after 24 hr in culture and increases during the next few days. Our results demonstrate that SLI is present very early in the quail embryo and that its appearance parallels the differentiation of neural crest cells into autonomic sympathetic ganglionic cells. We also show that the differentiation of neural crest into SLI-containing cells can be reproduced in culture, thus permitting the study of peptide production and expression in vitro.