Urinary System and Kidney Histology Outline PDF

Outline of the urinary system & Histology of the kidney Prepared by Dr. Amal Abd-El hafez Associate professor of histopathology 0  Objectives At the end of this lecture you will be able to:...

Outline of the urinary system & Histology of the kidney Prepared by Dr. Amal Abd-El hafez Associate professor of histopathology 0  Objectives At the end of this lecture you will be able to: Know the classification of the urinary system and its functions. Describe the anatomical and microscopic structure of the kidney. Discuss the histological structure of different parts of the nephron. Recognize the differences between proximal and distal convoluted tubules. 0  Introduction The urinary system consists of: kidneys [Rt., Lt.]and Urinary passages: renal pelvis and calyces, ureters; bladder; urethra and the urinary sphincters. 0  The Kidneys Anatomically, each kidney has: 1- Convex lateral border; 2-Concave medial border, called hilum where the ureter, blood vessels, nerves and lymph vessels enter and exit. 3-The renal pelvis, the expanded upper end of the ureter. 4- Two or three major calyces arising from the pelvis. 5- Several smaller minor calyces. 6-Loosely attached connective tissue capsule. 7- Peri-renal fat. 0  Urinary passages: Smaller minor calyces converge to open in 2-3 major calyces, then renal pelvis, and ureter which distally joins urinary bladder that connects with the urethra. 0  The Kidneys 0 Cut section of the kidney shows: 1.Outer cortex 2. Inner medulla: the renal medulla consists of 10- 18 conical or pyramidal structures, the medullary pyramids. 3.Renal columns: are the areas of the cortex separating the renal pyramids. 0 Histology: The Renal Parenchyma The renal parenchyma is composed of structural units called uriniferous tubules each formed of: A- Nephron: one million in each kidney; functional unit of the kidney which filters blood and excretes urine; formed of: 1-Renal [Malpighian] corpuscle 2-proximal convoluted tubule 3-loop of Henle 4-distal convoluted tubule B- Collecting duct: each duct drains 5 nephrons. 0  Nephron 0  1-The Renal [Malpighian] Corpuscle 0  Each renal corpuscle has 2 poles: 1. vascular pole, where the afferent arteriole enters & the efferent arteriole exit. 2. urinary pole, arises from the Bowman’s space between the parietal and visceral layers. It gives rise to the proximal convoluted tubules. 0 0  The podocytes 0  2-Proximal Convoluted Tubules Start at the urinary pole of the renal corpuscle. Lined by large cuboidal epithelial cells [3-5 cells in transverse section]. 0  3-Loop of Henle U shaped tubule connect the proximal with distal convoluted tubule Formed of: 1) Mainly thin descending limb, lined by simple squamous epithelium. 2) loop, 3) Mainly thick ascending limb, lined by simple cuboidal epithelium. 0  4-Distal Convoluted Tubules It is the extension of the ascending limb of Henle’s loop. Lined by low cuboidal epithelial cells [5-8 cells in transverse section 0  B- The Collecting Duct It is the extension of distal convoluted tubule. Each duct drains 5 nephrons. Lined by columnar intercalated cells and cuboidal principle epithelial cells. Function: 1-Re-absorption of water. 2-Conduction of urine to calyces. 0  Summary of renal tubules Proximal convoluted tubule – simple cuboidal with brush border of microvilli that increase surface area Descending limb of loop of Henle – simple squamous Ascending limb of loop of Henle – simple cuboidal to low columnar Distal convoluted tubule – Simple low cuboidal Collecting ducts – simple cuboidal/columnar composed of principal cells & intercalated cells which have microvilli. 0  Histological section of the renal cortex 0  Renal corpuscle 26-0  Prostate gland The prostate is one of the accessory glands of the male genital system and located below the urinary bladder surrounding the urethra at its origin 0  Histologically, 1. The prostate is surrounded by fibromuscular capsule rich in smooth muscle fibers. 2. Trabeculae: CT septae arise from the capsule and divide the gland into lobules 0 1. The prostatic acini are the secretory units of the gland that are arranged in 3 group: Peripheral zone: main group, large sized. Submucosal zone: medium sized. Mucosal zone: small sized, directly around urethra 2. They are lined by cuboidal or columnar cells according to activity of the gland. 0 5. Corpora amylacia (prostatic concretions): acidophilic lamellated calcified secretory material of the prostate located within the acini which increase with age 0  RECOMMENDED REFERENCES, WEBSITES Junqueira's Basic Histology: Text and Atlas, Thirteenth Edition 2013 ISBN-13: 978-0071780339 ISBN-10: 0071780335 Edition: 13th The histology tutor: http://www2.yvcc.edu/histology zoomer/HistologyTutorials/hi stology_tutorials.htm 0