In human tissues, VEGF121, VEGF165, and VEGF183 are expressed in virtually all cell types examined, with the notable exception of EC. VEGF145 is restricted to cell lines derived from female reproductive tract carcinomas and the placenta, and VEGF206, originally isolated from a fetal liver cDNA library, has been found in the placenta.
Investigation of VEGF isoform expression during murine development suggested that the isoforms are developmen-tally regulated. Quantitative analysis of isoform expression in developing and adult murine tissues revealed that while all VEGF isoforms are expressed in embryonic mouse organs, the relative levels of each isoform varied from organ to organ over developmental time . In the developing lung, heart, and liver, VEGF188 levels increased from embryonic day 13 to day 18 to account for more than 50 percent of the total VEGF mRNA, and remained high in the adult. In contrast, there were only slight increases in VEGF120 and VEGF164. Little VEGF188 was expressed in the developing or adult brain, with no change detected. In adult organs, lung had the highest relative level of VEGF 188, while eye, small intestine, and ovary had the lowest VEGF188 level. VEGF164 was predominant in brain, muscle, eye, and kidney. Finally, VEGF120 was highest in uterus, skin, and ovary . Differences in expression levels of VEGF isoforms in developing and adult organs are an indication that the isoforms have specific functions during developmental and adult angiogenesis.
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This ebook provides an introductory explanation of the workings of the human body, with an effort to draw connections between the body systems and explain their interdependencies. A framework for the book is homeostasis and how the body maintains balance within each system. This is intended as a first introduction to physiology for a college-level course.