CPR 11.03 Renal Histology

Question 1

Identify and Describe the renal capsule. What type of CT is it comprised of and why is this important?

Answer 1

Outermost section made of dense irregular CT to resist stress in multiple directions.

Question 2

ID and describe the renal cortex. What portions of the nephron are within this region?

Answer 2

parenchyma. Stains darkly. Has renal columns that extend into medulla. Contains Corpuscle, PCT, DCT, CT.

Question 3

Identify and describe the renal medulla. What parts of the nephron reside here?

Answer 3

Pale and striated, Renal Pyramids. Contains Loop of henle, DST, Collecting Ducts.

Question 4

Grossly describe the renal microvasculature incluindg the AA, Glomerulus, EA, Peritubular Caps/Vasa Recta, and Veinules

Answer 4

A. Afferent Arterioles: originates from interlobular arteries and enters glomerulus.
B. Glomerulus: loops of fenestrated capillary plexus within renal corpuscle.
C. Efferent arterioles: leaves glomerulus (small than ΑA)
1. Peritubular Capillaries: cortex, surround PCT or DCT
2. Vasa Recta: medulla, surround loops of Henle and Collecting Ducts
D. Veinules

Question 5

Describe the renal corpuscle and its fxn and the difference between the vascular and tubular poles

Answer 5

Basics : it is the initial dilated part of nephron, located in cortex, contains glomerulus, site of blood filtration.

1. Vascular Pole: entry/exit point of arterioles
2. Tubular pole: site where PCT begins (filtrate)

Question 6

What type of cells make up the glomerular capsule

Answer 6

Double Walled epithelium.

Question 7

Describe the parietal layer of the glomerular capsule including cell type, location, and what it is continuos with

Answer 7

outsie, simple squamous epithelium, basal lamina, continous with PCT.

Question 8

Describe the visceral layer of the glomerular capsule including cell type, location, and function

Answer 8

difficult to see, overlaps capillaries) enveolps glomerulus and contributes to filtration barrier. Consists of Podocytes rather than SSEpithelium.

(a) Podocytes: modified epithelial cells
(1) Primary processes: extend around glomerulus
(2) Pedicels (secondary): interdigitating process that cover capillary surface, filtration slit pores between pedicels.

Question 9

ID (In LM and EM) and describe the 3 main components of the glomerular filtration barrier.

Answer 9

A. Endothelium p. 25
1. Fenestrated capillary that only blocks blood cells and platelets.

B. Glomerular basement membrane (GBM) p. 25

1. Fused basal lamina of capillary endothelium and podocyte.
2. Thickest part of barrier, made of laminin, fibronectin, type IV collagen, and large proteoglycans.
3. Restricts large proteins and organic ions.

C. Filtration slit diaphragms p. 26

1. Covers filtration slit pores between peidcles.
2. Consists of nephrins glycoproteins, and proteoglycans
3. Restrict small proteins and organic anions.

Question 10

Identify (LM and EM) and describe mesangium and mesangial cells and their function

Answer 10

A. Mesangium is a matrix of BM-like material wthat fills space between capillaries and provides physical support.

B. Mesangial cells within mesangium look similar though darker than podocytes in LM.

1. They contract long processes along capillaries to help regulate filtration.
2. Function in phagocytizeing proteins and secreting cytokines and Prostaglandins.

Question 11

ID and Describe the location, appearance, and function of the PCT.

Answer 11

A. Proximal Convoluted Tubule (PCT) p. 32

1. Entirely in cortex. Simple cuboidal cells with microvilli brush border. Can’t see boundaries between cells.
2. Reabsorbs 65% of filtrate.

Question 12

ID and describe the location and appearance of the PST

Answer 12

B. Proximal Straight Tubule (PST) p. 33
1. Found in Cortex and then medulla in areas with parrallel arrangements. Made of simple cuboidal cells, microvilli brush border. Very similar to PCT

Question 13

ID and Describe the location and appearance (including cell type) of ascending/descending limps of the loop of henle

Answer 13

C. Thin A/D Limbs of Loop of Henle p. 34

1. Medulla. Simple squamous epithelium, Prominent lumen compared to capillary

Question 14

ID and Describe the location and appearance of the DST

Answer 14

D. Distal Straight Tubule (DST) p. 35

1. Ascends through medulla to Cortex. Cuboidal epithelium, NO Brush Border.

Question 15

ID and Describe the location and appearance of the DCT. what structure is formed from the DCT>

Answer 15

E. Distal Convoluted Tubule (DCT) p. 36

1. Completely in Cortex, forms macula densa.
2. Simple Cuboidal cells, No Brush border, more blue than DST.

Question 16

Describe the components and function of the Collecting tubule

Answer 16

1. Connects DCT to Collecting duct, Simple cuboidal epithelium that descend in medullary array (parralel).
2. Most likely indirect questions, hadrd to find!

Question 17

Describe the function and appearance of the collecting duct.

Answer 17

B. Collecting Duct p. 41

1. Delivers urine to minor calyx.
2. Consists of Cortical portion (cuboidal), Medullary portion (columnar), Papillary portion (apex of pyramid where several ducts merge→ Larger lumen).
3. Principal cells: pale, Very distinct cell borders, rich in aquaporins.
4. Intercalated Cells: darker staining, some microvilli, help maintina Acid-Base by secreting H+ or HCO3-

Question 18

ID and describe the location and function of the JGA

Answer 18

A. Basics of JGA (p. 49): At vascular pole, contact between ΑA and DCT via JG cells and Macula Densa and Lacis Cells→ Regulate glomerular blood flow to keep GFR Constant

Question 19

IX. Identify (in LM & EM) and describe the JG cells, macula densa, & Lacis cells

Answer 19

A. Macula Densa p. 50

1. Located in DCT, closely packed columnar, darkly stained
2. Monitors Na+ levels and ultrafiltrate volume.

B. JG Cells

1. Located in tunica media of afferent arteriole. Modified smooth muscle cells with rER, golgi, and granules that can secrete renin.
2. No basal lamina→ contact macula densa directly.

C. Lacis Cells
1. Pale mesangial cells that fill the gap between Macula Densa and JG cells outside glomerulus.