Three-dimensional architecture of the microvasculature in the rat foot-pad, with special reference to vasculature around the eccrine sweat glands. A scanning electron-microscopic study of corrosion casts.

The entire microvascular architecture in rat foot-pads including that of eccrine sweat glands was studied by scanning electron microscopy using a vascular corrosion-cast replication technique. In the central roofs of the pads, particularly elaborate capillary networks were arranged in rows perpendicular to the long axis of the foot. In the marginal regions of the pads, simple networks of capillaries were arranged in lamellar sheets parallel to the surface of the sole of the foot. Complex spongy networks of vascular trees were observed in the subcutaneous layer of the pads. These vessels were supplied by the pad artery, and then, after forming capillary networks in the roofs of the pads, they drained into the metatarsal vein. Rod-shaped cages of capillaries were observed around the eccrine sweat glands. One descending arteriole, arising from a connecting arteriole, and a few venules were connected with these capillary cages at their upper and lateral sides. Occasional arterio-venous and veno-venous anastomoses were also observed around the eccrine sweat glands. This microvascular architecture may adjust well to the mechanical and physiological conditions encountered in the foot-pads. The relation of the microvascular architecture around the eccrine sweat glands with their development is also discussed.