HISTOLOGY OF KIDNEY

Dr Iram Tassaduq

GENERAL ORGANIZATION OF RENAL STRUCTURE

Capsule Cortex • Cortical labryinth • Medullary rays Medulla • renal pyramids • cortical/renal

columns Renal pelvis Major and minor

calyxes

LOBES AND LOBULES

Each kidney lobe consists of a medullary pyramid and its associated cortex.

A renal lobule is defined as a portion of the kidney containing those Nephrons that are served by a common collecting duct.  

BLOOD SUPPLY

RENAL CAPSULE

Comprised of 2 layers

Outer mainly consist of collagen fibers

Inner mainly has

myofibroblast

URINEFEROUS TUBULE

Nephron Collecting

tubule

PARTS OF NEPHRON

RENAL CORPUSCLE

CORTICAL LABYRINTH

Renal corpuscle Convoluted

tubule

BOWMANS CAPSULE

GLOMERULUS

MESENGIAL CELLS

found within the glomerulus. These cells secrete a matrix of basement membrane-like material to support the structure of the glomerulus.

PROXIMAL CONVULATED TUBULE

Longest and tortous part of nephron

Commences at urinary pole

Occupies major part of cortex

Lined by low columnar epithelium

Show brush border Absorb sodium

LOOP OF HENLE The thin segment of Henle's loop leads

into the straight part of the distal tubule, which is formed by low cuboidal cells without a brush border. A few short microvilli are present

Epithelial cells in the ascending parts of the intermediate and straight distal tubules cells transport chloride (active) and sodium ions (passive) out of the tubular lumen into the surrounding peritubular space.

The epithelium can not be penetrated by water. Consequently, the transport of ions over the epithelium sets up a gradient in osmotic pressure, which serves as driving force in the further concentration of the urine.

DISTAL CONVULATED TUBULE

Slightly tortous Lined by simple

cuboidal epithelium Absorption of sodium

and chloride

COLLECTING DUCT

Excretory ducts Present in

medullary ray Lined by simple

cuboidal epithelium

Transport urine from nephron to renal pelvis

MEDULLARY RAYS

Formed of straight tubules and collecting duct

JUXTA GLOMERULAR COMPLEX

MACULA DENSA

Specialized region of DCT

Cells are tall columnar Closely packed nuclei Thin and discontinuous

basal lamina Release renin

JUXTA GLOMERULAR CELLS

Present adjacent to macula densa

Epithelioid cells in tunica media

Large in size Internal elastic lamina is

absent

EXTRA GLOMERULAR MESENGIAL CELLS

Form a cushion of cells between afferent and efferent arteriole

Structurally resemble intraglomerular cells

Functional significance not clear