Spatial mapping and quantification of developmental branching morphogenesis

Abstract

SUMMARYBranching morphogenesis is a fundamental developmental mechanism that shapes the formation of many organs. The complex three-dimensional shapes derived by this process reflect equally complex genetic interactions between branching epithelia and their surrounding mesenchyme. Despite the importance of this process to normal adult organ function, analysis of branching has been stymied by the absence of a bespoke method to quantify accurately the complex spatial datasets that describe it. As a consequence, although many developmentally important genes are proposed to influence branching morphogenesis, we have no way of objectively assessing their individual contributions to this process. We report the development of a method for accurately quantifying many aspects of branching morphogenesis and we demonstrate its application to the study of organ development. As proof of principle we have employed this approach to analyse the developing mouse lung and kidney, describing the spatial characteristics of the branching ureteric bud and pulmonary epithelia. To demonstrate further its capacity to profile unrecognised genetic contributions to organ development, we examine Tgfb2 mutant kidneys, identifying elements of both developmental delay and specific spatial dysmorphology caused by haplo-insufficiency for this gene. This technical advance provides a crucial resource that will enable rigorous characterisation of the genetic and environmental factors that regulate this essential and evolutionarily conserved developmental mechanism.

Large Scale Imaging by Fine Spatial Alignment of Multi-Scanning Data with Gel Cube Device

“…It frequently happens that undesired noise deteriorates the laser illumination imaging, and many studies of measurement systems [16,17], image algorithms [18,19], and reagent for sample preparation [20,21] have been improved to enhance image quality. However, achieving large-scale (millimeters) high-resolution 3D imaging remains difficult, due to the trade-off between the viewing range and NA of an objective lens.…”

A spatially-averaged mathematical model of kidney branching morphogenesis

“…Based on observations that tip size declines over time (Short et al, 2013), we assume that i u − (the threshold value for branching) decreases between successive generations. The following information provides partial justification for our assumption.…”

“…We used the experimental observations reported in (Short et al, 2013;Short et al, 2014) to estimate the parameters that appear in our mathematical model (see Appendix A for details). A list of the dimensional parameters, along with their default values are reported in Table 1.…”

“…While organs such as the lung have a more defined primary branching program (Metzger et al, 2008), synchronous and asynchronous dichotomous branching drive the bulk of lung development in ϱ a manner similar to other organs including the kidney (Short et al, 2013). In both cases, signals exist within the surrounding mesenchyme and that mesenchyme has been shown to play an instructive role, although not necessarily on organ shape but on final differentiation (Taylor et al, 2009).…”

The role of signalling pathways in urogenital ridge differentiation

“…After induction of the UB, this epithelial structure will undergo a series of sequential branching to forms the kidney collecting duct system (Short et al, 2013). As the ureteric bud starts to branch, the MM condenses around the ureteric tips to form the cap mesenchyme or "nephron progenitors" (Fig.…”