[P96]: Association and organization of cultured rat infantile pituitary cells after cell migration

Abstract

and elaboration of neuronal networks. Therefore, we chose the embryonic CNS as a model for examining mechanisms that coordinately regulate angiogenesis and neurogenesis.Methods: S-phase labeling methods were used to study cell proliferation; laser capture micro-dissection and real-time quantitative PCR to study gene expression profiles of angiogenesisrelated genes in neurogenic regions of the telencephalon.Results: Endothelial and neuroepithelial cell proliferation is concurrently active in the proliferative zones of the telencephalon early in embryonic development. However, later in embryonic development, endothelial cell proliferation continues in postmitotic domains independent of neuroepithelial cell proliferation. BrdU labeling indices in the ventricular and subventricular zones decline coordinately in endothelial and neuroepithelial cells from embryonic day 11 (E11) to E17. Differences between dorsal and ventral telencephalon were apparent in endothelial cell BrdU labeling patterns. Novel patterns of VEGF, Flt1, Flk1, Tie1 and Tie2 mRNA expression emerged in endothelial and non-endothelial cells in the proliferative zones from E11 to E17.Discussion: Our data lay the foundations for a comprehensive model of vascular and nervous system development and offer insights into molecules and mechanisms that integrate development and repair of both the systems.The mechanisms of neural and vascular patterning have many similarities including a reliance on similar sets of guidance molecules. Furthermore, physical interactions between the angioblasts/endothelial cells and neurons have been shown to pattern the vascular system during development. In zebrafish embryonic development, blood vessels in the trunk are guided to grow in a stereotypical pattern. The intersegmental vessels (ISV) of the trunk sprout from the dorsal aorta at approximately 19 h post fertilization (hpf) and migrate dorsally, restricted caudally, rostrally and laterally by the somites and medially by the notochord and neural tube. The out of bounds (obd) genetic zebrafish mutant has aberrant ISV patterning, such that angioblasts start migrating preciously from the dorsal aorta at approximately 17 hpf, and are no longer restricted by the somites caudally and rostrally. Positional cloning has identified endothelial-specific plexinD1 as the gene responsible for the obd phenotype. In the nervous system, plexins have been shown to serve as receptors for the semaphorin family of ligands. In order to further understand how ISV growth is guided, we have identified semaphorins expressed by trunk motoneurons that influence endothelial cell migration in the developing zebrafish trunk.We describe here a novel transgenic mouse line Hoxb7Core5 expressing Cre recombinase in a group of cells at the midbrain and hindbrain boundary. We used this mouse line in a cell lineage study mapping brain areas subject to the contribution from the initial population of cells expressing Cre recombinase in the Hoxb7Core5 mouse line.The Cre-mediated recombination pattern is described...