A prospective study evaluating tissue reactivity by light microscopic and pulse labeling-autoradiographic techniques is presented. One uterine horn of a Sprague-Dawley rat model was subjected to transection and reanastomosis using microsurgical techniques (control). The opposite horn of each was also cross-sectioned with the application of an absorbable topical hemostatic agent (Avitene) and then reanastomosed. After closure of the abdomen, the animals were randomly assigned to groups according to the planned day of sacrifice (days 3, 7, 14, 21, or 28). Autoradiographic techniques utilizing [3H]hydroxyproline or [3H]leucine as well as light microscopy were employed to determine tissue reactivity. The results demonstrated an increase in stromal (P less than or equal to .05) and smooth muscle (P less than or equal to .01) reactivity with [3H]leucine labeling, and an increase in smooth muscle (P less than or equal to 0.05) reactivity with [3H]hydroxyproline in the Avitene-treated groups. It is concluded that pulse labeling with tritiated leucine and hydroxyproline is an effective method of objective analysis of tissue reactivity in reproductive organs.