A morphometric method to evaluate angiogenesis kinetics in the rat mesentery.

The mesenteric window angiogenesis assay permits the objective determination of a number of angiogenesis parameters in peritoneal connective tissue. The time-course of the angiogenic response that follows activation of endogenous connective tissue mast cells in situ in normal adult rats was investigated using a set of quantitative variables. A method developed to quantify angiogenesis kinetics by evaluation of microvascular ramification and elongation is presented. The angiogenic process was found to proceed long after the termination of the inducing selective mast-cell activation and was thus to a large extent self-perpetuating. The angiogenesis also continued long after the maximum level of the ingrowth of vessels from adjacent tissues, the vessel density, and ramification within the vascularized areas was reached. The whole angiogenic phase lasted as long as 5-6 weeks and the total vessel density, i.e. the vascular area multiplied by the vessel density, remained elevated over controls throughout the course of the 99-day experiment. It appears that angiogenesis kinetics based on truly quantitative assessment of relevant parameters, as in the present study, will be a useful means in elucidating how positive and negative angiogenic factors, individually or in combination, influence the microvascular arborization.