The c-ret gene encodes a receptor tyrosine kinase that is expressed in the Wolffian duct and ureteric bud of the developing excretory system. Newborn mice homozygous for a mutation in c-ret displayed renal agenesis or severe hypodysplasia, suggesting a critical role for this gene in metanephric kidney development. To investigate the embryological basis of these defects, we characterized the ear...

The mechanisms by which the branching of epithelial tissue occurs and is regulated to generate different organ structures are not well understood. In this work, image analyses of the organ rudiments demonstrate specific epithelial branching patterns for the early lung and kidney; the lung type typically generating several side branches, whereas kidney branching was mainly dichotomous. Parameter...

It has been suggested that positional information along the proximo-distal axis of the limb-bud is specified by time spent in the progress zone. Mesenchyme cells have been killed by X-irradiation, reducing the rate cells leave the zone. The time spent there by some cells is thus increased. When limbs, stage 18/19, stage 21, or tips of stage 24, are treated with increasing doses of X-irradiation...

Endothelial to mesenchyme transition (EndMT) can be observed during the formation of endocardial cushions from the endocardium, the endothelial lining of the atrioventricular canal (AVC), of the developing heart at embryonic day 9.5 (E9.5). Many regulators of the process have been identified; however, the mechanisms driving the initial commitment decision of endothelial cells to EndMT have been...

INTRODUCTION A variety of craniofacial organs and tissues, such as the Meckel’s cartilage, maxillary and mandible bone, trigeminal ganglion and dentin-producing odontoblasts, derive from craniofacial neural crest cells (Chai et al., 2000; Chung et al., 2009). Despite originating from the same progenitor population, craniofacial bone and tooth exhibit distinct developmental, morphological and hi...

We have produced detailed fate maps for mesenchyme and apical ridge of a stage 20 chick wing bud. The fate maps of the mesenchyme show that most of the wing arises from the posterior half of the bud. Subapical mesenchyme gives rise to digits. Cell populations beneath the ridge in the mid apical region fan out into the anterior tip of the handplate, while posterior cell populations extend right ...

The sensory innervation of the dental mesenchyme is essential for tooth function and protection. Sensory innervation of the dental pulp is mediated by axons originating from the trigeminal ganglia and is strictly regulated in time. Teeth can develop from cultured re-associations between dissociated dental epithelial and mesenchymal cells from Embryonic Day 14 mouse molars, after implantation un...

Members of the Msx homeobox family are thought to play important roles in inductive tissue interactions during vertebrate organogenesis, but their precise developmental function has been unclear. Mice deficient for Msx1 exhibit defects in craniofacial development and a failure of tooth morphogenesis, with an arrest in molar tooth development at the E13.5 bud stage. Because of its potential for ...

In the early human embryonic/fetal pancreas, we studied 1) the ontogenetic pattern of the endocrine cells and the evolution of the endocrine mass, and 2) the morphogenetic pattern of development and, more precisely, the complex relationship of the epithelial mass with the surrounding mesenchyme. We studied 15 pancreases between 7 and 11 weeks of development (WD) by double immunohistochemistry. ...

Pancreatic organogenesis has been a classic example of epitheliomesenchymal interactions. The nature of this interaction, and the way in which endocrine, acinar and ductal cell lineages are generated from the embryonic foregut has not been determined. It has generally been thought that mesenchyme is necessary for all aspects of pancreatic development. In addition islets have been thought to der...