Small basal infolding from the epithelium form the glands of Littre which are mucus glands. In many instances, the glands of littre are intraepithelial glands but are continuous with glands of Littre in the lamina propria. The stroma around the urethra is richly cellular and vascular. Some of these sinuses are quite large and others smaller. They all fill with blood during erection.
Larger ones compress the smaller ones.
Note that they are lined by endothelium and that there are a number of coiled or helicine arteries associated with them. There are also blood sinuses and trabeculae in the spongiosum, but the sinuses are more uniform and are smaller than those of the cavernosa. The albuginea of the spongiosum is thinner than that of the cavernous bodies and contains more elastic fibers and circularly arranged smooth muscle fibers. The acrosome reaction occurs in the female tract not in the male tract but is essential to fertilization. Study the morphology of the sperm head in EM DEMO 8 and 9 .