Dynamic relationship of the epithelium and mesenchyme during salivary gland initiation: the role of Fgf10.

Kirsty L Wells,Danny Deutsch,David Rice,Eva Matalova,Abigail S Tucker,Marcia Gaete

doi:10.1242/bio.20135306

Abstract

SummarySalivary glands provide an excellent model for the study of epithelial–mesenchymal interactions. We have looked at the interactions involved in the early initiation and development of murine salivary glands using classic recombination experiments and knockout mice. We show that salivary gland epithelium, at thickening and initial bud stages, is able to direct salivary gland development in non-gland pharyngeal arch mesenchyme at early stages. The early salivary gland epithelium is therefore able to induce gland development in non-gland tissue. This ability later shifts to the mesenchyme, with non-gland epithelium, such as from the limb bud, able to form a branching gland when combined with pseudoglandular stage gland mesenchyme. This shift appears to involve Fgf signalling, with signals from the epithelium inducing Fgf10 in the mesenchyme. Fgf10 then signals back to the epithelium to direct gland down-growth and bud development. These experiments highlight the importance of epithelial–mesenchymal signalling in gland initiation, controlling where, when and how many salivary glands form.

Highlights

Salivary gland development is a dynamic process involving epithelial–mesenchymal interactions
Summary Salivary glands provide an excellent model for the study of epithelial–mesenchymal interactions
We have looked at the interactions involved in the early initiation and development of murine salivary glands using classic recombination experiments and knockout mice

Summary

Introduction

Salivary gland development is a dynamic process involving epithelial–mesenchymal interactions. Salivary glands develop in a series of well-characterised stages, pre-bud (epithelial thickening), initial bud, pseudoglandular, and canalicular (Tucker, 2007). The major salivary glands, submandibular, sublingual and parotid, develop from neural crest derived mesenchyme and ectoderm derived epithelium (Jaskoll et al, 2002; Rothova et al, 2012). A lot of information regarding branching morphogenesis is starting to be accumulated, initiation of the glands is less well understood. When E13 salivary gland epithelium was combined with other sources of non-glandular mesenchyme, such as from the maxilla, the epithelium failed to branch and formed a cyst (Grobstein, 1953b). It was suggested that salivary gland epithelium depended completely on its organ specific mesenchyme for correct morphogenesis (Kratochwil, 1969)

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