Microvascular architecture of the human urinary bladder wall: A corrosion casting study

Abstract

The vascular system of the urinary bladder wall effectively performs its function in spite of considerable spatial changes due to the filling/voiding cycle. However, only a few studies have dealt with the microvascular architecture of the bladder wall and only two, using old-fashioned techniques, were devoted to the human bladder. This study presents the microvasculature of the human bladder wall visualized by scanning electron microscopy of vascular corrosion casts. Postoperative bladder specimens obtained from patients with advanced bladder tumors were filled with small amount (80 ml) of saline and perfused via at least four largest arteries with anticoagulant-containing saline followed by paraformaldehyde/glutaraldehyde fixative and Mercox resin. After polymerization of the resin, the vascular casts were macerated with potassium hydroxide, cleaned with formic acid and water and freeze dried. Only regions of the bladder wall distant to the tumor were examined in light and scanning electron microscopes. The almost empty state of the bladder was manifested by extensive folding of the mucosa and tortuosity of almost all vessels other than capillaries. The branches of main arteries and veins formed an adventitial/serosal plexus which directly supplied/drained the capillary network of the muscularis and sent long perpendicular vessels to the mucosal plexus. These vessels had straight or coiled course depending on whether they terminated at the top or at the base of the mucosal folds. The rich mucosal plexus followed the folds parallel to their surface and gave off short, straight, mostly perpendicular twigs communicating with the subepithelial capillary network. Apart from very few vascular interconnections between the mucosal plexus and the muscularis, the submucosa was generally avascular. The subepithelial capillary network showed extreme density and uneven contours of the capillaries, only in less folded areas of trigone and urethral orifice the network was looser and capillaries thinner. The capillary system of the muscularis was poorly developed. Due to its architecture, tortuosity, and coiling/uncoiling capabilities, the microvasculature of the human urinary bladder wall seems to efficiently accommodate changes associated with cyclic contraction and stretching. Disturbances in blood flow induced by overdistension of the bladder reported in several studies may be due to pressure of the urine affecting the patency of the vessels rather than to the spatial insufficiency of the vascular system.

Linearized texture of three-dimensional extracellular matrix is mandatory for bladder cancer cell invasion

“…3d), based on shape and diameter (ranging between 25 and 235 μm, in agreement with previously reported diameters of veins and arteries in the healthy bladder34; 61 counts from the 10 tested MIBC-derived ECM). The ECM from MIBC was also characterized by a dense and compacted layer (Fig.…”

Lamina propria: The functional center of the bladder?

“…Few studies have been performed on the (micro)anatomy of human bladder vessels. Miodoński and Litwin performed a corrosion‐casting study on the human bladder wall. They identified two major vascular plexuses (adventitial/serosal and mucosal) and distinguished two distinct capillary networks (muscular and suburothelial) in the successive layers of the wall.…”

Chronic Pelvic Ischemia: Contribution to the Pathogenesis of Lower Urinary Tract Symptoms (LUTS): A New Target for Pharmacological Treatment?

“…Infiltrating the muscular layer, is a network of spiraled arteries with the capacity to lengthen and shorten, helping maintain sufficient perfusion to the different structures during bladder wall distension. The adventitia contains a further plexus, the adventitial plexus …”

“…There is a large amount of blood supply to the lamina propria, particularly the layer immediately beneath the urothelium. The urothelium has approximately three times greater metabolic activity than is observed in the detrusor muscle; if ischemia occurs, the functionality of urothelium will thus be affected first . This has functional implications for the mucosal signaling pathway as well as for maintaining the barrier function of the urothelium.…”