Blood vascular architecture of the rat parathyroid glands: a scanning electron microscopic study of corrosion casts.

Blood vascular beds of the rat parathyroid glands were reproduced with a methacrylate casting medium and observed with a scanning electron microscope. The rat possesses only a single pair (one left and the other right) of parathyroid glands. Each gland was found to contain a rich capillary network which was completely isolated from the capillary plexus of the thyroid gland. Each parathyroid gland received some small afferent arteries from the superior thyroid artery and emitted a thick efferent vein continuous with the superior thyroid vein. The capillary network of the parathyroid gland consisted of freely anastomosing capillaries. The afferent arteries were divided in the superficial and deep layers of the gland. The thick efferent vein arose in the deep layer of the gland. Some small or accessory efferent veins arose in the superficial layers of the gland. These also drained into the superior thyroid vein.