title: Expression of neuronal markers suggests heterogeneity of chick sympathoadrenal cells prior to invasion of the adrenal anlagen.
abstract: We have analyzed the distribution of neural crest-derived precursors and the expression of catecholaminergic and neuronal markers in developing adrenal tissue of chick embryos. Undifferentiated neural crest cells are found in presumptive adrenal regions from embryonic day 3 (E3) onward. An increasing proportion of cells expressing tyrosine hydroxylase (TH) mRNA indicates catecholaminergic differentiation of precursors not only in primary sympathetic ganglia, but also in presumptive adrenal regions. Whereas precursors and differentiating cells show mesenchymal distribution until E5, discrete adrenal anlagen form during E6. Even during E5, catecholaminergic cells with low or undetectable neurofilament M (NF-M) mRNA expression prevail in positions at which adrenal anlagen become distinct during E6. The predominance of TH-positive and NF-M-negative cells is maintained throughout embryogenesis in adrenal tissue. RNA encoding SCG10, a pan-neuronal marker like NF-M, is strongly expressed throughout adrenal anlagen during E6 but is found at reduced levels in chromaffin cells compared with neuronal cells at E15. Two additional neuronal markers, synaptotagmin 1 and neurexin 1, are expressed at low to undetectable levels in developing chromaffin cells throughout embryogenesis. The developmental regulation of neuronal markers shows at least three different patterns among the four mRNAs analyzed. Importantly, there is no generalized downregulation of neuronal markers in developing adrenal anlagen. Thus, our observations question the classical concept of chromaffin differentiation from a common sympathoadrenal progenitor expressing neuronal properties and suggest alternative models with changing instructive signals or separate progenitor populations for sympathetic neuronal and chromaffin endocrine cells.
authors.affiliation: Department of Neuroanatomy, Interdisciplinary Center for Neurosciences (IZN), University of Heidelberg, INF 307, 69120 Heidelberg, Germany. uwe.ernsberger@urz.uni-heidelberg.de
authors.forename: Uwe
authors.initials: U
authors.lastname: Ernsberger
authors.forename: Lorena
authors.initials: L
authors.lastname: Esposito
authors.forename: Sandra
authors.initials: S
authors.lastname: Partimo
authors.forename: Katrin
authors.initials: K
authors.lastname: Huber
authors.forename: Aylin
authors.initials: A
authors.lastname: Franke
authors.forename: John L
authors.initials: JL
authors.lastname: Bixby
authors.forename: Chaya
authors.initials: C
authors.lastname: Kalcheim
authors.forename: Klaus
authors.initials: K
authors.lastname: Unsicker
mesh_terms: D000311:Adrenal Glands / Q000166:cytology* / Q000196:embryology / Q000378:metabolism; D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D002395:Catecholamines / Q000096:biosynthesis* / Q000235:genetics; D002454:Cell Differentiation; D002642:Chick Embryo; D019439:Chromaffin Cells / Q000166:cytology / Q000378:metabolism; D005728:Ganglia, Sympathetic / Q000166:cytology* / Q000196:embryology / Q000378:metabolism; D017403:In Situ Hybridization; D009432:Neural Crest / Q000166:cytology / Q000196:embryology / Q000378:metabolism; D016900:Neurofilament Proteins / Q000096:biosynthesis / Q000235:genetics; D009474:Neurons / Q000378:metabolism*; D012333:RNA, Messenger / Q000096:biosynthesis; D013234:Stem Cells / Q000166:cytology / Q000378:metabolism; D013997:Time Factors; D014446:Tyrosine 3-Monooxygenase / Q000096:biosynthesis / Q000235:genetics
chemical_list: D015415:Biomarkers; D002395:Catecholamines; D016900:Neurofilament Proteins; D012333:RNA, Messenger; D014446:Tyrosine 3-Monooxygenase