Case 6 Histology Flashcards
describe the the renal corpuscle and functional unit of kidney
- Afferent arteriole (from interlobular vessel)
- Glomerulus
- Bowman’s capsule (distended end of urinary tube) (simple squamous cells -> simple cuboidal when turns into proximal tubule – helps see where changes to tubule)
- Bowman’s space
- Basement membrane
- Efferent arteriole
- Peritubular capillary
- Proximal convoluted tubule (may be higher up than distal and more to right)
- Loop of Henle
- Distal convoluted tubule
- > collecting tubule ->
- Collecting duct (has a number of tubules going into it)
describe the histology of the cortex (epithelium) (lumen)
- Renal corpuscles – round structures (only in cortex)
- glomerulus – structures on inside of white circle – capillary network
- bowman’s capsule – white round circle
- Proximal convoluted tubules (sometimes see this from corpuscle)
- simple cuboidal epithelium
- brush border (for a lot of reabsorption – lots of microvilli) ((has microvilli but these will not be evident on LM) – most numerous of the tubules)
- small lumen
- Distal convoluted tubules
- simple cuboidal epithelium
- no brush border – no microvilli
- smaller with a proportionally larger lumen than PCT (difficult to see this) – due to no microvilli
- Capillary network between tubules
Tubules will be cut into in different planes – may be transverse through tubule so looks more like a tube or might be cross-section so just roundish circle
describe what’s in the medulla (epithelium)
- Thick descending limb
- cuboidal epithelium
- Thin descending & ascending limbs
- simple squamous epithelium
- Thick ascending limb
- low cuboidal epithelium
- Collecting tubules
- low cuboidal epithelium
- Collecting ducts
- low columnar epithelium
- Vasa recta (capillaries around collecting ducts and loop of Henle)
- The shape of the ducts will depend on whether they are being examined in transverse, longitudinal or oblique plans – it is likely that you will see them in all three
- Remember the cut section may show the tubules as tubes or as circles
what is the renal corpuscle?
glomerulus & Bowman’s capsule
describe the different parts of the kidney
- Capsule
- Cortex
- Medulla
- Papilla
- Ureter
- Hilum
- Capsule
- Fatty tissue around
- All stained basically same colour – not the colour different used to seeing between cortex and medulla
what are the poles of the renal corpuscle?
- Vascular pole – where blood vessels come in
- Urinary pole – where proximal tubule leaves
what are the two types of nephron? describe them.
Cortical nephron – short loops of Henle – they won’t go for into the medulla
- Interlobular artery
- Afferent arteriole
- Glomerulus
- Efferent arteriole
- Peritubular capillaries (just these, they go round the loop of Henle too, but short so don’t have vasa recta)
- Then to interlobular veins
Juxtamedullary nephron – long loop of Henle – a lot will go into the medulla
- Afferent arteriole
- Efferent arteriole
- Peritubular capillaries
- Vasa recta
- Then to interlobular veins
describe the renal corpuscle and juxtaglomerular apparatus
- what is it
- what is it made up of
- what for
- Might see juxtaglomerular apparatus (= a specialised structure formed by the distal convoluted tubule and glomerular afferent arteriole – it is located near the vascular pole of the glomerulus and its main function is to regulate blood pressure and the filtration rate of the glomerulus)
- Made up of two components
- some cells within the distal convoluted tubule – macula densa – these cells are right next up to the afferent arteriole
- area in afferent arteriole that they’re up against have some specialised cells called juxtaglomerular cells (specialised smooth muscle cells mainly in the walls of the afferent arterioles that secrete renin)
- This structure is monitoring the blood volume – and indirectly the blood pressure
- The macula densa (cells look a bit more dense where the distal convoluted tubule is caught on to arteriole) measure the concentration in sodium in the filtrate
- And the afferent arterioles looks at the stretch of the wall to monitor the volume of blood flow – renal perfusion
- If blood flow goes down, we secrete renin and it’s the juxtaglomerular cells that produce this renin -> renin-angiotensin system
how do you identify the cortex and medulla in the kidney?
Cortex
At low power identify
- Renal corpuscle – the give away for the cortex
- Proximal tubule – assume this if see a circle where the lumen is very small
- Distal tubule – near the vascular pole
- Capillary network
- It appears that you have much more proximal tubules as they are much more convoluted than the distal tubules
At high power identify
- Glomerulus
- Bowman’s space
Medulla
- Loops of Henle – rays of tubes coming down but not always in a nice straight line
- Collecting ducts
- Look at whether cuboidal or squamous epithelium – see whether thick or thin parts of the loop of Henle
how is urine moved through ureter to bladder?
by peristalsis
what are the layers of the ureter?
4 layers: 1. epithelium 2. lamina propria 3. muscularis 4. adventitia or 3 layers: 1. mucosa 2. muscularis 3. adventitia
describe the epithelium of the ureter - what important about it?
- consists of 3-6 rows of cells
- impermeable to urine even when stretched
- ureters are lined by transitional epithelium (urothelium)
- The basal cells are cuboidal in shape, small nuclei
- The intermediate cells are said to be columnar with their nuclei arranged at right angles to the basement membrane
- The surface cells (innermost) are referred to as umbrella (urine spinkling down on you, you want umbrella up) or dome cells (ovoid) – they ensure that the wall is impermeable to urine even when stretched
- These cells give the inner wall of the ureter a scalloped appearance
- (more circular near bottom, then taller cells and then the dome cells)
what does the lamina propria of the ureter do? what composed of and contain?
- supports the endothelium
- relatively thick
- composed of dense irregular connective tissue
- contains nerves and blood vessels
- bundles of connective tissue fibres are clearly visible as are some blood vessels, lymphatics and nerves
describe the muscularis layer of ureter - what important for?
- inner fibres arranged longitudinally (opposite to what get in rest of GI tract) and outer fibres circularly
- however, sections taken at the lower (1/3) end of the ureter will display an additional layer of longitudinal fibres on the outside
- responsible for peristalsis
describe the adventitia of the ureter - what does it contain?
- loose connective tissue layer
- contains adipose cells (significant component), blood vessels and nerves
- (looks thicker than expected)
