Three-dimensional architecture of collagen fibrils in the mouse testicular capsule

The three-dimensional architecture of collagen fibrils in the mouse testicular capsule was studied after digestion of cellular and some extracellular elements by 10% NaOH. In the tunica vaginalis, the collagen fibrils were interwoven in an irregular and complex pattern. The tunica albuginea consisted of successively stacked lamellae of collagen bundles, which were arranged parallel to the testicular surface and ran across their neighbors at almost right angles. This arrangement of collagen fibrils appears to be effective in giving the testis its rigidity. Further, the collagen bundles in the tunica albuginea showed more or less undulating courses. It is suggested that the bundles undergo alteration from straight to undulate, to permit contraction of the testicular capsule.