Pathology of the Urinary System (Kidney, Urinary Tract, Bladder)

Plan: Lecture 1: Recap of anatomy and physiology, clinical aspects of renal disease, pathogenesis of glomerulonephritis Lecture 2:Morphologic expressions of glomerular injury, primary glomerular diseases Lecture 3:Primary glomerular disease

Introduction. Weight 150 g Cortex (1.5 cm) and medulla Renal pelvis - 2 to 3 major calyces - each 3-4 minor calyces.

Filters about 1700 L of blood to prepare 1 L of urine

Anatomical structure of parenchyma..  Lobe  Lobule  Cortex  Medulla

Anatomical structure of parenchyma.  Lobules  Cortex o Columns of Bertin  Medulla (O, I) o Pyramid o Papilla

The Cortex Labyrinth Medullary rays

Vasculature Renal artery - anterior and posterior br ---- interlobar ---- arcuate --- interlobular ---- afferent arteriole ---- glomerulus ---- efferent arteriole ---- peritubular capillaries ---- vasa recta ---- venous vasa recta ---- renal vein

Vascular structure of parenchyma

Renal vasculature Arteries are end arteries Glomerular diseases can compromise vascular supply to other components Medulla is relatively avascular and vulnerable to ischemia Cortex is more vulnerable to hypertensive changes

The Nephron

(Pathology) Compartments Glomeruli Tubules Interstitium Blood vessels

Glomerulus Formation Components Structure

Glomerulus Formation Components Structure Bowmans capsule Parietal epithelial cells Visceral epithelial cells Basement membrane Endothelial cells Mesangial cells Mesangial matrix

Glomerulus Formation Components Structure Bowmans capsule Parietal epithelial cells Visceral epithelial cells Basement membrane Endothelial cells Mesangial cells Mesangial matrix

Glomerulus Formation Components Structure Filtration membrane fenestrated endothelial cells ( nm); glomerular Basement Membrane visceral epithelial cells -podocytes (20-30 nm)

Glomerulus Formation Components Structure Glomerular basement membrane: - Thick inner lamina densa - Lamina rara externa and interna. Collagen IV, laminin, polyanionic proteoglycans, intermediate filaments, other glycoproteins. Filtration is governed by size and charge.

The Glomerulus

Basement Membrane: (LM) Identified better using special stains such as PAS (Per-iodic acid Schiff) Silver impregation methods Invests capillaries incompletely, and is continuous with capsular BM

Juxta-glomerular apparatus JG cells of afferent arteriole, macula densa of DCT, Lacis cells of mesangium Principal source of renin

Tubules and interstitium Proximal tubules: Rich in mitochondria, microvilli, canaliculi and interdigitations - Major site for re-absorption of water, glucose, sodium, potassium, phosphate, proteins, amino acids. Vulnerable to vascular and toxic injury.

... Histology of PCT

Proximal tubules: Abundant granular cytoplasm Distal tubules: Cuboidal cells

Loops of Henle, and Collecting Ducts

Interstitium: Scanty in the cortex and outer medulla More abundant in inner medulla