Renal Lecture 2
3/17/2003, 10 am
Patrick Cammarata, PhD
David Cummings
Page 1 of 3
Renal Histology 1
Dr. Cammarata started lecture slightly winded (since he found out that he was giving the lecture
that morning) but still able to give us a small overview of what to expect in the renal system and
then how to approach the histo. He stressed in the beginning of the class (and whenever we
reached the next slide) that renal slides are very busy and how important it is to not only expose
ourselves to the slides, but also to learn references to help us identify the structures on the slides.
Make sure to pay special attention to where the slide comes from in the kidney. Anyone that is
having trouble doing this is advised to come to him in a group of similarly needy students. With
this said I decided to cheat a little and use his outline adding in lecture notes. Enjoy :p BTW a
pretty neat site to check some of this histo out is
http://www.med.uiuc.edu/histo/small/atlas/index.htm or
http://www.anatomy.uq.edu.au/histology/contents/urinary/text.html. If you are very lazy at least
look at the pictures on both of these sites (since these slides can easily be confusing I suggest
looking at all the slides you can!!!)
I.
Gross structure of the kidneys – Basically inside the kidney you have the renal pyramids
(the dark pink stuff that is actually trapezoidal), each of which drains into a minor calyx. The part
of the pyramid touching the minor calyx is the papilla. The minor calyces combine to form 2-3
major calyces, which then form one renal pelvis. From the renal pelvis springs the ureter. The
renal lobes are formed if one draws a line longitudinally along two of the columns of Bertin
surrounding a medullary pyramid (and making a piece of pie).
G.
Hilum – Where all the stuff (Vein, Artery, Ureter) enters the kidney
Renal pelvis – Where all the urine gathers before going down the ureter
Major calyces – Where the minor calyces feed into
Minor calyces – Where the renal papilla feeds into
Medulla – The region of the kidney where the renal pyramid is
Medullary pyramids
Medullary rays – Classically composed of Ascending and Descending Thick
Loops of Henle and a Collecting Tubule. The slides we will have may not have
all three visible but we should still be able to identify this. It begins in the
Cortex/Medullary Border and continues into the medulla. Know the three
components of a medullary ray!!!
Renal lobe – 10 to 18 lobes in a human kidney. These are separated by the
renal columns
Renal lobule
H.
Columns of Bertin – The columns between the renal pyramids
A.
B.
C.
D.
E.
F.
G.
F.
II.
III.
Nephron: major functional unit of the kidney, includes renal corpuscle and renal
tubules. AKA – Glomerulus, Bowman’s capsule, Prox/Dist Convoluted Tubules,
Ascending/Descending Loop of Henle.
Renal corpuscle -- glomerulus plus Bowman’s capsule
IV.
Blood supply – Grab a book and look at the arteries (net pics if you don’t have a
book: http://www.anatomy.uq.edu.au/histology/contents/urinary/Bloods1.JPG and
http://www.anatomy.uq.edu.au/histology/contents/urinary/vessels.JPG). The Interlobular
arteries branch into the afferent arterioles which then feed into the glomerulus. The
blood then passes into an efferent arteriole. Note the order: AA to Glom to EA.
A.
Renal artery -- supplies blood to the kidney
B.
Interlobar arteries -- between renal pyramids
C.
Renal Lecture 2
3/17/2003, 10 am
Patrick Cammarata, PhD
David Cummings
Page 2 of 3
Arcuate arteries -- at the junction of between the cortex and the medulla
D.
Interlobular arteries -- traverse cortex radially between lobules
E.
Afferent arteriole -- come off at right angles to interlobular arteries and supply
blood to capillaries of glomerulus
F.
Glomerulus
G.
Efferent arteriole -- leaves glomerulus
H.
Peritubular capillaries - nourishes proximal and distal tubules and carries away
absorbed ions and low molecular weight proteins. Stays in the Cortex
I.
Vasa recta -- fed by efferent arterioles of juxtamedullary nephrons; course
parallel to long loops of Henle and nourish medulla Goes to the Medulla. Differentiated
from the two thin limbs because it has RBC’s. Otherwise Thin limbs and the vasa
recta look the same.
V.
Glomerulus – Always located in the Cortex. Identifies the cortex.
A.
A capillary bed: dense capillary network
B.
Fenestrated endothelial cells with diaphragms (originally this said no diaphragms
which was corrected in class)
C.
Mesangial cells – Little cells in the basal lamina that unclog the pores.
Phagocytic?
VI.
Bowman’s capsule – For Bowman’s capsule and the glomerulus the filtration works this
way. If you haven’t seen a picture of the podocyes you first need to see a nice picture like this
http://www.med.uiuc.edu/histo/small/atlas/image/m49/6000a1.htm and
http://www.anatomy.uq.edu.au/histology/contents/urinary/LEMfilbar.JPG. Note the podocyte.
The foot processes in the picture are called pedicels. Therefore the podocyte does not make
direct contact with the capillary, but instead sends out processes to do so. These processes are
spaced about 25 nm apart. Molecules and water pass through the capillary endothelium, the
basal lamina and then through a pore with a diaphragm into bowman’s capsule.
A.
Double walled epithelial capsule
B.
Parietal (external) layer of simple squamous epithelium
C.
Visceral (internal) layer of podocytes with primary processes and secondary
processes (pedicels) that embrace the glomerular capillaries
D.
Urinary space is the cavity between parietal and visceral layers. AKA Bowman’s
Space
E.
Vascular pole is where afferent arteriole enters and efferent arteriole exits
F.
Urinary pole is where proximal convoluted tubule begins. Cuiboidal Cells
G.
Filtration barrier – 25 nm pore that allows <70 kdal molecules in. Electrostatic
portion repulses negative charges.
VII.
Proximal convoluted tubule – Cuiboidal Cells. Very eosinophilic therefore hot pink.
Fuzzy center because it absorbs a lot. Note that if you have a Renal Corpuscle
slide you can have both proximal and distal so learn to tell them apart. Also
remember that the glomerulus is part of the cortex.
VIII.
Loop of Henle – Thick Descending Limbs look like Proximal Convoluted. Thick
Ascending looks like Distal Convoluted. Thin limbs look like capillaries since they
are lined with simple squamous. We won’t be asked to differentiate between
ascending and descending thin limbs. Vasa Recta looks exactly like the Thin
Limbs but has RBC’s. Loops may be sectioned longitudinally. Note the lack of a
corpuscle on these slides.
A.
Thick descending limb
Renal Lecture 2
3/17/2003, 10 am
Patrick Cammarata, PhD
David Cummings
Page 3 of 3
IX.
X.
XI.
XII.
B.
Thin descending limb
C.
Thin ascending limb
D.
Thick ascending limb
Distal convoluted tubule – Cuiboidal Cells. Lighter pink. No fuzzy innards. Found in
a Renal Corpuscle slide
A.
Simple cuboidal epithelium (no brush border)
B.
In cortex of kidney
C.
Macula densa - modified portion of distal convoluted tubule where it lies
adjacent to the vascular pole of the renal corpuscle Look for a lot of overlapping
cuboidal cells in a DCT. Basically you will have a nice wall near a glomerulus that
has really dark overlapping nuclei in a line.
Collecting tubules – Cuboidal Cells with one special condition = They have clear
lateral borders. What’s that???? Well, the lateral margin of the cell has a nice line
that says that this is where cell one stops and cell two begins. Just find one to
confirm. Note that like CT’s will be found with the loops of Henli and may be cut
longitudinal.
Collecting ducts (Papillary Ducts of Bellini) – Columnar Cells. All the slides I have
seen come with a minor calyx. Take a wild guess where these ducts are located in
the kidney (Hint: papillary). Collecting ducts are just the fused collecting tubules
(similar to the aforementioned minor calyx/major calyx structure).
Uriniferous tubule – Transitional Epithelium