Renal System Histology Lab

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Renal System Histology Lab
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• This laboratory is concerned with the
  identification of the histological features of
  the Renal System. It includes a study of the
  following components Kidneys, Ureter, Urinary
  Bladder, and Urethra..Be able to distinguish
  each of these structures and their salient
  features.

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• Kidney. Each kidney is enveloped by a dense
• connective tissue capsule. On the concave
• side of the kidney, there is an indentation, the
• hilum, through which the renal artery enters
• and the renal vein and ureter exit. Deep to
• the capsule, the parenchyma consists of a
• cortex and medulla. The medulla is comprised
• of about 10-18 pyramidal-shaped structures
• called Pyramids. The base of each pyramid is
• directed towards the capsule. The apex of each
• pyramid is called a papilla. The inset is an
  enlarged view of the papilla. In a longitudinal
  view, the pyramids appear striated due to the
  presence of parallel tubules (loops of Henle and
  collecting ducts) and blood vessels (vasa recta).
  The cortex is located between the bases of the
  pyramids and the capsule. Cortical tissue also
  fills in between the pyramids and is referred to
  as renal columns. The cortical tissue consists
  primarily of renal corpuscles and convoluted
  tubules. Some straight tubules (collecting ducts)
  project from the pyramids into the cortex. Such
  an area of the cortex is referred to as pars
  radiata. The rest of the cortical tissue is
  referred to as pars convoluta.The central
  portion of the kidney contains a saccular
  structure call the renal pelvis (3). 2-3 tubular
  structures, major calyces (2) project from the
  pelvis. The 2-3 major calyces branch into 10-18
  minor calyces (1). Urine passes from a pyramid
  into a minor calyx, into a major calyx, and then
  renal pelvis. The urine then exits the pelvis via
  the ureter.

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Renal Column
Capsule
Medulla (pyramid)
papilla
Pars radiata
Pars convoluta
Cortex
Minor calyses
Major calyses
Renal Pelvis
Ureter
Renal Sinus
PeePee
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Kidney. This is a low magnification image of a
section through a kidney. The blue line separates
the cortex above from the medulla below. The
pyramid, containing straight tubules and blood
vessels, is cut in cross-section. The cortex
contains renal corpuscles (black arrows) and
convoluted tubules. A blood vessel (arcuate
artery), near the center, is cut in
cross-section.
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Cortex. These are high magnification images of
the cortex of a kidney illustrating two renal
corpuscles. These structures consist of a
Bowmans capsule and a tuft of capillaries termed
glomeruli (sing glomerulus). The wall of the
Bowmans capsule is lined by a simple squamous
epithelium termed the parietal epithelium (green
arrows). The surface of the capillaries is
covered by a visceral epithelium. While the cells
of the visceral epithelium are classified as a
simple squamous epithelium, they are termed
podocytes due to their specialized structure. The
space located between the glomerulus and the
parietal epithelium is termed the urinary space
(U).
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Renal corpuscle. This is a high magnification
image of a renal corpuscle illustrating the
parietal epithelium (black arrows) and a
glomerulus (glom). Most of the nuclei associated
with the glomerulus are those of the podocytes. A
urinary space (U) is located between the
glomerulus and the parietal epithelium.
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Cortical tubules. These are high magnification
images of two types of tubules located in the
cortex proximal and distal convoluted tubules.
These tubules are lined by a simple cuboidal
epithelium. Collecting ducts are not illustrated
here. The red arrow is pointing to a proximal
convoluted tubule (cut longitudinally) projecting
off a renal corpuscle. Urine enters these tubules
from the urinary space. The black arrows
illustrate proximal convoluted tubules cut in
cross-section. These tubules have very irregular
lumenal surfaces due to the presence of
microvilli. They tend to stain the darkest of the
three types of cortical tubules. The green arrows
illustrate cross-sections of distal convoluted
tubules. These tend to stain lighter than the
PCTs and have a smooth lumenal surface.
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Arcuate artery. This image illustrates a
cross-section through an arcuate artery, which
passes along the corticomedullary junction (and
parallel to the surface). These arteries are
branches of interlobar arteries. Interlobular
arteries branch from the arcuate arteries and
pass into the cortex along a path indicated by
the red arrow. These arteries then give rise to
afferent arteries, which supply blood to the
glomeruli.
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Medulla. These images are cross-sections through
a pyramid illustrating three types of medullary
tubules. As the PCTs pass into the medulla, they
become Thin Loops of Henle (red arrows). These
tubules are lined by simple squamous epithelium.
The thin loops of Henle are continuous with Thick
Loops of Henle (TLH), which pass towards the
cortex. These latter tubules, lined by a simple
cuboidal epithelium, pass into the cortex as
distal convoluted tubules. Structurally, the
thick loops of Henle and the DCTs are similar.
They are identified by their location. Collecting
ducts can be distinguished from thick loops of
Henle in that the cells of the collecting ducts
tend to bulge toward the lumen and cell-to-cell
borders are fairly easy to distinguish.
Cell-to-cell borders are difficult to distinguish
in the thick loops of Henle.
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Medulla. This image is of a cross-section through
a pyramid illustrating several thin loops of
Henle (red arrows) and some collecting ducts
(CD). See previous page for their descriptions.
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Papilla. The image on the left is a scanning
electron micrograph of a papilla within a minor
calyx. Urine passes from the collecting ducts of
the papilla (also known as papillary ducts) to
the minor calyx. The image on the right is a
light microscopic image of a papilla (area within
the blue circle in the left image). Collecting
ducts (CD) are seen opening into the minor calyx
to the left.
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Macula Densa. Ascending into the cortex, the DCT
approximates its own renal corpuscle. As it does
so, there appears on the side of the wall of the
DCT facing the renal corpuscle a collection of
cells known as the macula densa. These cells are
readily identifiable as the nuclei are very close
together (red arrows). The macula densa and the
J-G cells of the afferent arterioles constitute
the juxtaglomerular apparatus
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Transitional Epithelium. Transitional epithelium
(red circle) lines the caleces, pelvis, ureter,
bladder and part of the urethra. It is a
stratified epithelium consisting mostly of
polygonal cells. The surface cells (green arrows)
have a modified surface to withstand the high
tonicity of the urine. These cells tend to bulge
towards the lumen and are known as dome or
balloon cells.
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Ureter. The image on the left is a low
magnification image of a ureter. Note that the
mucosa (epithelium (red arrows) and underlying
lamina propria (black arrows)) contain high
rising folds giving it a corrugated appearance.
The outer portion of the wall contains smooth
muscle (blue arrows). The image on the right is
a high magnification of one of the folds. The
dome cells are not obvious in these sections.
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Urinary Bladder. The image on the left is a low
magnification of a urinary bladder. The mucosa
consists of transitional epithelium (black
arrows) and lamina propria (green arrows). The
black line indicated the transition between the
mucosa and the muscular coat. The muscular coat
consists of three layer of smooth muscle an
inner longitudinal layer (above the blue line) a
middle circular layer (below the blue line) and
an outer longitudinal layer (not shown) The image
on the right is a higher magnification
illustrating the mucosa.
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• Think you know your stuff now?
• Go on and try to get everything right.
• If you can, you will get 100 on the lab part.
• If not, maybe medicine isnt your calling!!!

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PCT (note dark staining)
DCT (note light staining)
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Papilla
Pyramid
Minor Calyx
Minor Calyx
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DCT (note smooth lumen)
PCT
PCT (note irregular lumen)
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Renal corpuscle
???
Cortex
Arcuate artery
???
Medulla
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CD
Collecting Duct
                                                                                          
                                                                                          
Thin Loop of Henle
Thin Loop of Henle
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Collecting Ducts (note the peepee)
?
Minor Calyx
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Renal corpuscle
Glomerulus
Bowmans capsule
PeePee space
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Smooth muscle orientation? Longitudinal
Lamina propria
Transitional epithelium
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Macula Densa JG cells of afferent arterioles
???
JG Apparatus
Glomerulus
DCT
Macula Densa
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Thin Loop of Henle
7. ?
TLH
4. ?
TLH
1. ?
TLH
5. ?
TLH
2. ?
TLH
6. ?
CD
3. ?
CD
8. ?
TLH
Thin Loop of Henle
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Type of Tissue?
Transitional Epithelium
Surface cells (aka Dome Cell, aka Balloon Cell)
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PeePee space
Hint ??
Glomerulus
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Dome (balloon) cells
Lamina Propria
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Transitional epithelium
Lamina propria
Layers ? Epithelium Longitudinal Smooth
m. Circular Smooth m.
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What tissue is this? Ureter
Mucosa
Lamina propria
Smooth Muscle
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Collagen fibers
Elastic fibers
                                                                                          
                                                                                          
Connective tissue cell nucleus
Mast cells