Renal

Question 1

What are columns of Bertin?

Answer 1

Interlobar cortical tissue and CT → separates the lobes of the kidney

Question 2

What are the different sections of the nephron?

Answer 2

1. Renal corpuscule (contains glomerular tuft)
2. Proximal convoluted tubules (in medullar, very eosinophilic)
   Loop of Henle:
3. Thick straight descending limb (medulla, crosses cortico-medullary junction)
4. Thin limb (mostly descending, cortex)
5. Thick straight ascending limb (cortex)
   End of loop of Henle
6. Distal convoluted tubule (stained paler, medulla)
   *DCT drains into the collecting system

Question 3

What are the 2 parts of the Urininferous tubule?

Answer 3

1. Nephron
2. Collecting system:
   - Collecting tubules in the cortex
   - Collecting duct in the medullar (larger)

*Uniferous tubules = functional uni of the kidney
- Both parts differ in embryological origin
- Ends in the papillary duct of Bellini which opens the renal papilla in the area cribrosa

Question 4

What are the different structures of the renal corpuscule?

Answer 4

Glomerulus (fenestrated capillaries) + Bowman’s capsule

Bowman’s capsule has 2 epithelial layers:
- Visceral layer (podocytes)
- Parietal layer (squamous cells resting on BM, with reticular fibers on the outside)

In between there is a capsular space in which the ultrafiltrate goes before entering the urinary pole → Proximal convoluted tubule

Each renal corpuscule has a vacular pole (afferent and efferent arteriole) and urinary pole (PCT starts)

Question 5

What is the epithelium in the parietal layer of the renale corpuscule and how does it change at the urinary pole?

Answer 5

Parietal layer → Simple squamous epithelium
At urinary pole → PCT → simple columnar epithelium

Question 6

What are pedicels?

Answer 6

They are the 2ndary processes of the podocytes (from visceral layer of renal corpuscule)
- Interdigitated with pedicels from adjacent podocyte
- Form filtration slits (25nm wide) → bridged by bery thin diaphragm
- Touch BM (only part of podocytes that do)
- Cell bodies of podocytes are poor in mitochondria
- Processes contain actin filaments for contractility

Question 7

What type of capillaries are found in the glomerulus?
What are features of the BM the endothelial cells rest on?

Answer 7

Fenestrated capillaries
- no diaphragm

Endothelial cells share a thick BM with pedicels
BM contains type IV collagen, laminin, fibronectin, proteoglycans rich in heparan sulfate

Question 8

What is the problem of diabetes mellitus at the level of the kidney?

Answer 8

The BM around the capillaries is damaged → more permeable to proteins

*BM also acts as a filter

Question 9

Where are mesengial cells found?

Answer 9

1. Extraglomerular mesangial cells
   - At the vascular pole, outside the glomerulus, between the afferent and efferent arterioles
2. Intraglomerular mesangial cells
   - Between capillary loops inside glomerulus
   - Likely phagocytic + involved in digestion of BM
   - Maybe also contractile → reducing blood flow in glomerulus
   - Provide structure

Question 10

What is the macula densa?