Incomplete vascular casting for a scanning electron microscope study of the microcirculatory patterns in the rat pancreas.

Scanning electron microscopy of resin casts prepared by incomplete arterial injections showed that in the rat pancreas, the casting medium fills blood capillaries in the endocrine islets more promptly than those in the exocrine lobules and secretory ducts. Furthermore, the exocrine lobules containing endocrine islets allowed a more rapid resin flow through the insulo-acinar portal route than those lobules lacking an islet. The secretory ducts were the last portions to be filled with resin. Since the resin medium used in this study was as viscous as blood and injected under a physiological pressure, the microcirculatory modes demonstrated by the present method suggest the physiological flow of blood in the rat pancreas.