A MORPHOMETRIC METHOD TO EVALUATE ANGIOGENESIS KINETICS IN THE RAT MESENTERY

The mesenteric window angiogenesis assay permits the objective determi nation of a number of angiogenesis parameters in peritoneal connective tissue. The time-course of the angiogenic response that follows activ ation of endogenous connective tissue mast cells in situ in normal adu lt rats was investigated using a set of quantitative variables. A meth od developed to quantify angiogenesis kinetics by evaluation of microv ascular ramification and elongation is presented. The angiogenic proce ss was found to proceed long after the termination of the inducing sel ective mast-cell activation and was thus to a large extent self-perpet uating. The angiogenesis also continued long after the maximum level o f the ingrowth of vessels from adjacent tissues, the vessel density, a nd ramification within the vascularized areas was reached. The whole a ngiogenic phase lasted as long as 5-6 weeks and the total vessel densi ty, 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 ass essment of relevant parameters, as in the present study, will be a use ful means in elucidating how positive and negative angiogenic factors, individually or in combination, influence the microvascular arborizat ion.