Ovulation involves damage to the follicle connective tissue. Porcine tissue was used to examine the nature of this ovulatory change. Strips were cut from follicles about 20 (stage I), 5 (stage II), and 1 (stage III) hr. prior to rupture. The 2-x 20-mm sections were inserted in a tension-recording apparatus and subjected to acid, heat, or distension. The follicle collagen contracts at pH 3.0 or lower. After 5 min. at pH 2.0 the tension increased by 1.7 g in stage I, 1.5 g in stage n, and 1.4 g in stage HI. All three follicle stages contracted at 59 C. When heated to 70 C the tension increased by 2.1 g, 1.6 g, and 1.9 g, respectively. When slowly elongated 2.0 mm over a 15-min interval, the strip tension increased by 6.8 g, 3.1 g and 1.0 g, respectively. As rupture approaches, the follicle wall becomes more labile to dissociation under stress. The decomposition does not cause an appreciable reduction in the acid or heat contractility characteristic of the individual collagen fibrils.