Pliable metacrylate casts of blood vessels: use in a scanning electron microscope study of the microcirculation in rat hypophysis.

Methyl methacrylate mixed with 30-50 percent hydroxy ethyl or hydroxy propyl methacrylate produces a pliable replica suited to manipulation. The advantages of this improved casting medium were discussed, demonstrating the scanning electron micrographs of the isolated and dissected blood vascular replica of the rat cerebral hypophysis. In the micrographs it was unequivocally indicated that the vascular bed of the anterior lobe is supplied by the capillary plexus of the median eminence and the neural stalk, and that the vascular meshwork of the intermediate lobe is formed by vessels extended from the posterior lobe and is drained into the anterior lobe. The subependymal network intercalated between the plexus of the median eminence and the meshwork of the hypothalamus is directly supplied by arterial branches. It was also demonstrated that the plexus of the median eminence is, at its periphery, in direct communication with the systemic venous twigs.