Three-dimensional architecture of collagen fibrils in the mouse corpus cavernosum penis.

The three-dimensional architecture of the collagen fibrils in the corpus cavernosum penis of the mouse was studied after digestion of cellular and some extracellular elements by NaOH. The tunica albuginea was made up of undulating bundles of collagen fibrils which were arranged in outer longitudinal and inner circular layers. In both layers, several bundles were successively stacked to show the conspicuous lamellar arrangement. On the outer surface of the tunica, the collagen fibrils were interwoven like lacework. The trabecula appeared as a group of collagen bundles which extended from the inner circular layer of the tunica and showed a wavy arrangement. The grouped bundles in the trabecula were covered with a delicate sheath of collagen fibrils. These architectural features of the collagen fibrils appear to be related to fluctuations in the diameter and shape of the corpus during erection and detumescence.