Abstract
Summary: The three-dimensional architecture of the collagen fibrils in the corpus cavernosum of the crab-eating monkey was studied by scanning electron microscope, after digestion of cellular and some extracellular elements by NaOH. The tunica was made up of undulating bundles of collagen fibrils which were arranged in inner circular, middle intermingled and outer longitudinal layers. The trabecula appeared as numerous cylindrical tubes which had once accommodated individual smooth muscle fibers. The outer surface of the trabecula was covered with a sheath woven from twisting bundles of collagen fibrils. These architectural features of the collagen fibrils seem to be related to fluctuations in the diameter and shape of the corpus during erection and detumescence.
