Angiography of the crus penis in the ram and buck during erection.

Serial angiography was used to determine blood flow patterns to the penis of rams and bucks. Animals were anesthetized and the internal pudendal artery was catheterized so that contrast medium could be injected toward the crus penis area. By comparing vascular patterns of the ram and buck during erection, it was found that flow patterns of the corpus cavernosum penis (CCP) and corpus spongiosum penis (CSP) were similar for both species. Contraction of the ischiocavernosus muscles occluded the arterial inflow and venous outflow to the CCP, making it a closed system during peak erection. However, during erection, the contrast medium continued to flow into the CSP, showing that it is not a closed system. In the vasodilatation phase, the CSP usually filled before and more intensely than did the CCP.