Histology

Question 1

Hemisected Kidney

Answer 1

Shown are

A. cortex B. medulla C. renal pyramids (encircled regions) D. minor calyx E. major calyx F. ureter G. renal papilla

Question 2

Cortex of the Kidney

Answer 2

Cortex of the Kidney

1. connective tissue capsule at the surface of the kidney
2. renal corpuscles (encircled in blue)
3. straight coursing collecting tubules
4. interlobular arteries
5. convoluted tubules (region encircled in yellow: types cannot be easily distinguished at this magnification)
6. renal corpuscles in which the glomerulus is mostly out of the plane of section.

Question 3

Cortex and Junction with Medulla

(cortex is on right)

Answer 3

1. rays of collecting tub ules (gross anatomical term for parallel collections of collecting tubules)
2. approximate junction of cortex and medulla (yellow line)
3. blood vessels

Question 4

Junction of cortex and medulla with mostly medulla shown in the micrograph. The cortex is at the left.

Answer 4

1. collecting tubules and/or ducts.
2. thin segments of loops of Henle (interspersed between collecting tubules as light regions, encircled, red—these

regions also contain the vasa recta).

3. renal corpuscle of a juxtamedullary nephron (encircled, yellow)

Note: Renal corpuscles are not present in the medulla. Regions of connective tissue are stained blue-green.

Question 5

Answer 5

Renal Medulla

Note larger collecting tubules or ducts that have resulted from fusion of lesser collecting tubules (arrows). Bluestaining material is interstitial connective tissue. Fibroblasts, wandering phagocytes, and cells that produce mRNA for erythropoietin are found in the interstitium in the medulla and cortex. Notice tubules come into and pass out of the plane of section.

Question 6

Junction of the medulla and a minor calyx.

Answer 6

This section shows collecting ducts and papillary ducts formed from the fusion of collecting ducts. Papillary ducts open into minor calices of the renal pelvis. Dark staining streak is a fold in the section.

1. urinary space of the calyx. Note the epithelium is continuous with the papillary (and collecting) ducts.
2. papillary ducts – collecting ducts drain via the papillary ducts into the minor calices.

Question 7

A renal corpuscle showing entry of the afferent arteriole:

Answer 7

1. arteriole
2. glomerulus
3. urinary space of the corpuscle
4. intralobular artery
5. simple squamous epithelium lining Bowman’s capsule.

Question 8

A renal corpuscle showing entry of the afferent arteriole:

Answer 8

1. arteriole
2. glomerulus
3. urinary space of the corpuscle
4. intralobular artery
5. simple squamous epithelium lining Bowman’s capsule.

Question 9

Higher magnification of the corpuscle

Answer 9

1. probable J.G. cells.
2. portion of macula densa in adjacent distal tubule
3. lumen of glomerular capillaries
4. nuclei of podocytes and mesangial cells (cannot readily always distinguish)
5. nuclei of parietal epithelial cells (of Bowman’s Capsule)

Question 10

Renal corpuscle showing afferent arteriole in cross section:

Answer 10

1. arteriole in x-section. Note nuclei of endothelial and smooth muscle cells of the arteriole.
2. proximal convoluted tubules (columnar, note microvilli of brush border).
3. distal convoluted tubules (DCT, much smoother looking lumenal surface of epithelium).

Question 11

Answer 11

The urinary pole (beginning of proximal tubule) is indicated with arrows for both renal corpuscles.

Question 12

Answer 12

1. glomerular capillary lumen (note the fenestrated endothelium).
2. Nucleus of endothelial cell.
3. Foot processes of the podocytes (pedicels).
4. The filtration barrier.
5. The urinary space of Bowman’s capsule.
6. Mesangial cell nucleus. Note the basal lamina between podocyte processes and the fenestrated endothelium. It is the primary molecular filtration barrier.

Question 13

Low magnification EM micrograph showing greater detail of proximal tubule (large photo).

Answer 13

1. Lumen of the proximal tubule.
2. Nuclei of the epithelial cells.
3. Microvillar brush border.
4. just an apical vacuole.
5. Mitochondra
6. lysosomes.

Question 14

Higher magnification showing portions of interdigitated epithelial cells

Answer 14

1. lumenal space. 2. microvillar brush border. 3. tubular invagination of the apical membrane. 4. junctional complexes between epithelial cells. 5. apical vacuole. 6. Mitochondria. 9. lysosomes. 10. nucleus. 12. indicates basal infolds of the basolateral plasma membrane. Why the junctional complexes?

Why have so many mitochondria near the basal infolds? (Think about what the main role of these cells is and these answers should be obvious).

Question 15

This is a section through the medulla with longitudinal views of tubules.

Answer 15

1. Descending thick segment of proximal tubule (note brush border as a “fuzzy” lumenal lining).
2. thin segment of loop of Henle.
3. Collecting tubule or duct.
4. Ascending thick segment of distal tubule (lack of significant brush border, see next image).

Arrow—shows the junction of a thin segment (flattened squamous epithelium) with a thick segment, in this case the

ascending (distal) portion of the Loop of Henle.

Question 16

Urinary Bladder.

Answer 16

1. lining of transitional epithelium
2. prominent lamina propria
3. Smooth muscles (spanned by line).

Distension of the bladder prevents reflux back into the ureters.

Question 17

EM of junction between ascending thin and thick segments.

Answer 17

Note again abrupt change in epithelium. 1. lumen of thin segment. 2. lumen of thick segment (note: this is an ascending distal segment because there is no significant brush border). 4. nucleus of squamous epithelial cell of thin segment of loop of Henle. 5. peritubular capillaries, 7. abundant mitochondria in thick segment.

Question 18

Low magnification electron micrograph showing cross section through a thin segment and adjacent blood

vessels.

Answer 18

1 = lumen of thin segment of loop of Henle. Note the thin wall, although thicker than the endothelial cell linings of 4 and 5.

2 = wall of a portion of the thick segment.

4 and 5 = vasa recta

6 = nucleus of connective tissue cell

Question 19

• nephrotic syndrome
• normal light microscopy
• negative IF
• EM w/ foot process fusion

Answer 19

Minimal Change Disease

Question 20

• nephrotic syndrome

Answer 20

Focal Segmental Glomerulosclerosis

Question 21

• nephrotic syndrome

Answer 21

Membranous Nephropathy

Question 22

• nephrotic syndrome

Answer 22

Membranoproliferative Glomerulonephropathy Type 1

Question 23

• nephrotic syndrome

Answer 23

Membranoproliferative GN Type 1

Question 24

• nephrotic syndrome

Answer 24

Membranoproliferative GN Type 2

Question 25

• nephritic

Answer 25

IgA Nephropathy

• mesangial immune complexes containing IgA

Question 26

• nephritic

Answer 26

Lupus Nephritis

• immune complex deposition

Question 27

• nephritic

Answer 27

Anti-GBM Disease

• antibody to glomerular antigen

Question 28

• nephritic

Answer 28

ANCA Assoiciated Vasculitis

• small vessel vasculitis

Question 29

• nephritic

Answer 29

Thin Basement Membrane Disease

– Also known as benign familial hemauria

(excellent prognosis)

– Occurs in 1% of the population

– Mutations in genes encoding collagen IV

– Need to differentiate from Alport’s syndrome

– Diagnosis based on electron microscopy

Question 30

• nephritic

Answer 30

Alport’s Disease

• Triad of nephritis, deafness, and ocular

lesions

• Due to mutation in alpha-5 chain of collagen IV
• X-linked
• Can’t form normal basement membranes
• Definitive diagnosis based on finding the basketweave pattern on electron microscopy
• Usually progress to end stage renal disease