Localised axial progenitor cell populations in the avian tail bud are not committed to a posterior Hox identity

Michael J Mcgrew,Valerie Wilson,Kyriacos A Mitrophanous,Pippa A Radcliffe,Fiona M Ellard,Simon G Lillico,Adrian Sherman,Hazel J Gilhooley,Noemí Cambray,Helen Sang

doi:10.1242/dev.022020

Abstract

The outgrowth of the vertebrate tail is thought to involve the proliferation of regionalised stem/progenitor cell populations formed during gastrulation. To follow these populations over extended periods, we used cells from GFP-positive transgenic chick embryos as a source for donor tissue in grafting experiments. We determined that resident progenitor cell populations are localised in the chicken tail bud. One population, which is located in the chordoneural hinge (CNH), contributes descendants to the paraxial mesoderm, notochord and neural tube, and is serially transplantable between embryos. A second population of mesodermal progenitor cells is located in a separate dorsoposterior region of the tail bud, and a corresponding population is present in the mouse tail bud. Using heterotopic transplantations, we show that the fate of CNH cells depends on their environment within the tail bud. Furthermore, we show that the anteroposterior identity of tail bud progenitor cells can be reset by heterochronic transplantation to the node region of gastrula-stage chicken embryos.

Highlights

During gastrulation, the three germ layers of the embryo are formed by cell ingression from the epiblast through the primitive streak
We investigated whether long-term axial progenitors (LTAPs) populations are present in the chicken tail bud during its outgrowth
In a series of grafting experiments, we show that the chicken tail bud contains distinct spatially localised populations of both LTAPs and Short-term axial progenitors (STAPs)

Summary

Introduction

The three germ layers of the embryo are formed by cell ingression from the epiblast through the primitive streak. These cells take up residence along the developing anteroposterior axis of the body during primitive streak elongation and regression. As in other vertebrates, closure of the posterior neuropore ends the process known as primary body development, driven by the primitive streak. The primitive streak and tail bud supply cells to the neural tube and mesoderm over the entire post-cranial axis (Schoenwolf, 1977; Schoenwolf, 1979a; Catala et al, 1995; Psychoyos and Stern, 1996). The nascent embryonic chick tail subsequently undergoes reduction and remodeling by selective proliferation, involution and cell death (Lanot, 1980; Schoenwolf, 1981; Sanders et al, 1986; Uehara and Ueshima, 1988; Miller and Briglin, 1996)

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Conclusion