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We labeled axonal projections using carbocyanine dyes in the developing rat brain to study cellular interactions that might underlie the establishment of thalamocortical connectivity. By embryonic day 14 (E14), groups of neurons in the ventral diencephalon and the primitive internal capsule have established projections to the dorsal thalamus, and thalamic(More)
Chemical synapses contain specialized pre- and postsynaptic structures that regulate synaptic transmission and plasticity. EphB receptor tyrosine kinases are important molecular components in this process. Previously, EphB receptors were shown to act postsynaptically, whereas their transmembrane ligands, the ephrinBs, were presumed to act presynaptically.(More)
New blood vessels are initially formed through the assembly or sprouting of endothelial cells, but the recruitment of supporting pericytes and vascular smooth muscle cells (mural cells) ensures the formation of a mature and stable vascular network. Defective mural-cell coverage is associated with the poorly organized and leaky vasculature seen in tumors or(More)
The Notch pathway is a highly conserved signaling system that controls a diversity of growth, differentiation, and patterning processes. In growing blood vessels, sprouting of endothelial tip cells is inhibited by Notch signaling, which is activated by binding of the Notch receptor to its ligand Delta-like 4 (Dll4). Here, we show that the Notch ligand(More)
In the mutant mouse reeler, the tangential distribution of thalamocortical fibers is essentially normal, even though neurons of the cortical plate accumulate below the entire early-born preplate population (Caviness et al., 1998). This seems incompatible with the hypothesis that cells of the subplate (the lower component of the preplate in normal mammals)(More)
Members of the collapsin/semaphorin gene family have been proposed to act as growth cone guidance signals in vertebrates and invertebrates. To identify candidate molecules involved in axonal pathfinding during mouse embryogenesis, we isolated cDNAs encoding five new members of the semaphorin family (Sem A-Sem E). The murine semaphorin genes are(More)
The transmembrane ligand ephrinB2 and its cognate Eph receptor tyrosine kinases are important regulators of vascular morphogenesis. EphrinB2 may have an active signaling role, resulting in bi-directional signal transduction downstream of both ephrinB2 and Eph receptors. To separate the ligand and receptor-like functions of ephrinB2 in mice, we replaced the(More)
In development, tissue regeneration or certain diseases, angiogenic growth leads to the expansion of blood vessels and the lymphatic vasculature. This involves endothelial cell proliferation as well as angiogenic sprouting, in which a subset of cells, termed tip cells, acquires motile, invasive behaviour and extends filopodial protrusions. Although it is(More)
Notch signaling has been shown to regulate various aspects of vascular development. However, a specific role of the ligand Delta-like 1 (DLL1) has not been shown thus far. Here, we demonstrate that during fetal development, DLL1 is an essential Notch ligand in the vascular endothelium of large arteries to activate Notch1 and maintain arterial identity. DLL1(More)
To better understand the regulatory processes underlying axonal pathfinding we analyzed the embryonic expression of seven murine semaphorin genes by in situ hybridization In the spinal cord, transcripts of all seven semaphorin genes were detected from Embryonic Day 11.5 (E11.5) onward and restricted to distinct regions at E15.5. Interestingly, semE, F, and(More)