Strongylocentrotus purpuratus embryos were fractionated into two cell populations of defined lineages at times corresponding to two critical developmental events: determination (16-cell stage) and early differentiation (mesenchyme blastula). The 16-cell stage blastomeres, labeled with [35S]methionine, exhibited identical protein synthesis patterns by fluorography, and this pattern was not signi...

Limb development constitutes a central model for the study of tissue and organ patterning; yet, the mechanisms that regulate the patterning of limb vasculature have been left understudied. Vascular patterning in the forming limb is tightly regulated in order to ensure sufficient gas exchange and nutrient supply to the developing organ. Once skeletogenesis is initiated, limb vasculature undergoe...

We show that the mesenchymal cells that surround the 12-d mouse embryo thymus are necessary for T cell differentiation. Thus, epithelial lobes with attached mesenchyme generate all T cell populations in vitro, whereas lobes from which mesenchyme has been removed show poor lymphopoiesis with few cells progressing beyond the CD4(-)CD8(-) stage of development. Interestingly, thymic mesenchyme is d...

Within the developing vertebrate head, neural crest cells (NCCs) migrate from the dorsal surface of the hindbrain into the mesenchyme adjacent to rhombomeres (r)1 plus r2, r4 and r6 in three segregated streams. NCCs do not enter the intervening mesenchyme adjacent to r3 or r5, suggesting that these regions contain a NCC-repulsive activity. We have used surgical manipulations in the chick to dem...

Mesenchyme is an embryonic precursor tissue that generates a range of structures in vertebrates including cartilage, bone, muscle, kidney, and the erythropoietic system. Mesenchyme originates from both mesoderm and the neural crest, an ectodermal cell population, via an epithelial to mesenchymal transition (EMT). Because ectodermal and mesodermal mesenchyme can form in close proximity and give ...

Epithelia from lung rudiments in which secondary bronchial buds are already established (14th and 13th gestational day for rat and mouse respectively) are able to undergo branching morphogenesis and cytodifferentiation in submandibular mesenchyme in vitro, whereas lung epithelium from one day younger foetuses rarely gives a morphogenetic response to submandibular mesenchyme and usually differen...

The role of gap junctional communication during patterning of the chick limb has been investigated. Affinity-purified antibodies raised against rat liver gap junctional proteins were used to block communication between limb mesenchyme cells. Co-injection of the antibodies and Lucifer yellow into mesenchyme cultures demonstrated that communication was inhibited almost immediately. When antibodie...

OBJECTIVE Pancreas organogenesis is orchestrated by interactions between the epithelium and the mesenchyme, but these interactions are not completely understood. Here we investigated a role for bone morphogenetic protein (BMP) signaling within the pancreas mesenchyme and found it to be required for the normal development of the mesenchyme as well as for the pancreatic epithelium. RESEARCH DES...

Epithelial-mesenchymal interactions are critical for normal pancreas development. Fibroblast growth factor (Fgf)-10 is expressed in the pancreatic mesenchyme and its signalling is required for normal growth and regulation of gene expression in the pancreatic epithelium. However, little is known about putative Fgf signalling to the mesenchyme. Here we have examined the embryonic pancreas express...