MICROVASCULARIZATION OF CORPUSCLES OF STANNIUS IN TELEOST FISHES

Blood supply and microvascular patterns of Stannius corpuscles were st udied by scanning electron microscopy of vascular corrosion casts in t he teleost fishes Blennius pave, Zosterisessor ophiocephalus, and Gast erosteus aculeatus. Microvascular casts demonstrated that Stannius cor puscles-depending on their location-have an arterial supply derived ei ther directly from the dorsal aorta, from the trunk of the first ventr al segmental artery of the tail, or from a renal artery. Supplying art eries form a capsular capillary bed and a parenchymal capillary bed; b oth are composed of fine, freely anastomosing vessels with a homogeneo us isotropic distribution. Central venules arise deep in the corpuscle s. In the capsule, they form a single vein which drains into a segment al vein or directly into the caudal vein. Stanniocalcin, the hormone o f the Stannius corpuscle, enters the renal circulation and reaches its main target organs, the gills, via posterior cardinal veins-heart-ven tral aorta. Occasionally, some capsular venules empty into the trunk k idney peritubular venules. Capillaries are fenestrated and are embrace d by pericytes with long, slender processes. The perivascular space co ntains collagen fibrils. Nerve fibers are found close to endothelial c ells and pericytes. Vascular patterns of Stannius corpuscles are compa red with those of the rat parathyroid glands and are discussed in resp ect to physiological implications. (C) 1995 Wiley-Liss, Inc.