Coronary angiogenesis. From morphometry to molecular biology and back

We have reviewed briefly the current state of knowledge relating to the regulation of angiogenesis, including the role of angiogenic growth factors, and we have described the major structural components of the vascular wall and their changes during formation of new channels. Finally, we have described quantitative evaluations of vascular growth in cardiac muscle. Examples of substantial angiogenesis during the early postnatal stages of normal development were used together with examples depicting a more moderate stimulation of capillary growth in adult rat hearts treated with nifedipine or thyroxine. Adequate capillary supply is a precondition for tissue survival and proper function. This is probably why vascular growth is so tightly regulated by several systems which may alternately stimulate or inhibit the formation of new vessels. Recent advances in molecular biology have enabled us to study the mechanisms of angiogenesis under both in vitro and in vivo conditions, but the final assessment of vascular growth should be accomplished through morphometric analysis.