Using Micropaque (crystallized barium sulphate) in a gelatinous medium of a certain viscosity, with a fluorescent pigment in the solution, we obtained a mixture with a fluidity adequate to a vascular injection; this injection is performed with a constant pressure, the values of which are kept between limits near the values of the physiological arterial pressure. We found several types of arterio-luminal vessels with different calibres: some of them with a calibre of 200 µm, some others of the intermediate type with a calibre between 100 and 200 µm, and others, which we call arterio-Thebesian vessels, originating in arteriolar branches opening in the Thebesian veins. At last, we have the arterio-sinusoido-cavitary vessels opening in the ventricular cavities by several orifice