Case 6 Histology Flashcards
1
Q
describe the the renal corpuscle and functional unit of kidney
A
- 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)
2
Q
describe the histology of the cortex (epithelium) (lumen)
A
- 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
3
Q
describe what’s in the medulla (epithelium)
A
- 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
4
Q
what is the renal corpuscle?
A
glomerulus & Bowman’s capsule
5
Q
describe the different parts of the kidney
A
- 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
6
Q
what are the poles of the renal corpuscle?
A
- Vascular pole – where blood vessels come in
- Urinary pole – where proximal tubule leaves
7
Q
what are the two types of nephron? describe them.
A
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
8
Q
describe the renal corpuscle and juxtaglomerular apparatus
- what is it
- what is it made up of
- what for
A
- 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
9
Q
how do you identify the cortex and medulla in the kidney?
A
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
10
Q
how is urine moved through ureter to bladder?
A
by peristalsis
11
Q
what are the layers of the ureter?
A
4 layers: 1. epithelium 2. lamina propria 3. muscularis 4. adventitia or 3 layers: 1. mucosa 2. muscularis 3. adventitia
12
Q
describe the epithelium of the ureter - what important about it?
A
- 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)
13
Q
what does the lamina propria of the ureter do? what composed of and contain?
A
- 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
14
Q
describe the muscularis layer of ureter - what important for?
A
- 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
15
Q
describe the adventitia of the ureter - what does it contain?
A
- loose connective tissue layer
- contains adipose cells (significant component), blood vessels and nerves
- (looks thicker than expected)
16
Q
describe the mucosa of the ureter
A
- Mucosa is thrown into folds – these allow the ureter to distend when urine is passing through
17
Q
what are the layers of the bladder wall?
A
same three layers as ureter
18
Q
describe the mucosa of the bladder
- what stain used
A
- Arranged in folds
- Transitional epithelium (a stratified tissue made of multiple cell layers, where the cells constituting the tissue can change shape depending on the distention in the organ – found lining the bladder, ureters and urethra)
- Thick lamina propria (with Masson’s trichrome stain the collagen fibres are stained blue)
19
Q
describe the muscularis layer of the bladder
A
(like the lower end of the ureter)
- Inner longitudinal layer
- Middle circular layer
- Outer longitudinal layer
20
Q
describe the adventitia layer of the bladder
A
- Connective tissue (blue)
- Contains arteries, veins, lymphatics and nerves
21
Q
what does the suprarenal gland consist of?
A
- connective tissue capsule surrounding the gland
- outer cortex and an inner medulla
- cortex presents three distinct layers; zona glomerulosa, zone fasicularis and zona reticularis (GFR to remember)
22
Q
what does the zona glomerulosa secrete?
A
secretes mineralocorticoids (glowing from all the minerals you eat)
23
Q
what does the zona fasciulata secrete?
A
secretes glucocorticoids
FSG - fasiculata secretes glucocorticoids
24
Q
what does the zona reticularis secrete?
A
secretes androgens (rihanna – reana)
25
describe the cortex of the adrenal gland
- The outer cortex is not uniform in appearance
- Zona glomerulosa
- cells arranged in clusters separated by connective tissue
- cells have round nuclei and less cytoplasm that those in adjacent layer
- Zona fasiculata
- broadest layer in the cortex
- cells arranged in narrow columns separated by connective tissue
- quite large cells with pale cytoplasm (due to abundance of lipid granules/droplets) (I thought glomerulosa layer appeared paler)
- Zona reticularis
- innermost layer
- thinnest layer in cortex
- cells arranged as branching cords interspersed with clusters (mixture of clusters and columns) (cells are arranged in irregular network of branching cords interspersed with clusters of cells)
- cells smaller than those of zona fasiculata and cytoplasm stained darker
26
describe the medulla of the adrenal gland
(more purple structure in the middle of gland)
- Consists of large cells arranged in clusters
- They are supported by connective tissue which contains numerous capillaries
- Large veins are evident in the middle of the medulla
- Chromaffin cells – secrete adrenaline and noradrenaline – they’re supposedly a ganglion (the cortex is affected by hormones whereas in the medulla pre-ganglionic neurones come down and synapse with chromaffin cells)
27
what happens when adrenal gland stained with Masson's trichrome?
when stained with Masson’s trichrome, which stains connective tissue blue green, the capsule is easily seen and the connective tissue between the cells is more evident
- Section stained with Masson’s trichrome which stains connective tissue blue/green
- Note the capsule and connective tissue between cells easily seen
- Capsule = blue/green
28
what is stained what when bladder stained with Masson's trichrome stain?
muscle is stained red, connective tissue blue and cytoplasm pink
29
what is the urethra composed of?
- Two corpus cavernosa and one corpus spongiosum – spongiosum at the top with the urethra in the middle of it – squished white circled – very squished, not even circle
- The slit-like urethra can be easily identified in the middle of the corpus spongiosum (penis)
30
describe the epithelium of the urethra in sections taken through different parts of penis
- The epithelium can be variable
- In the prostatic urethra it is transitional, in the glans penis it is stratified squamous and in the remained of the male urethra (including spongy urethra) it may be stratified columnar or pseudostratified columnar (or stratified squamous)
- A number of paraurethral glands can be seen in the connective tissue of the corpus spongiosum – their mucoid secretions lubricate the urethra
31
what does the prostate gland consist of?
- Dense capsule contains vessels & nerves on one side of the tissue
- A combination of glandular tissue and supporting stroma is evident
- Stroma – mixture of connective tissue and smooth muscle fibres
32
describe the glandular component of the prostate gland
- Wide lumen
- Epithelium thrown in to folds
- Glandular epithelium – simple columnar epithelium with tall cells and round, basally located nuclei – but does vary in some areas
- In this slide, the epithelium appears quite variable – there appears to be some stratification and the cells appear cuboidal with round nuclei
- In many glands prostatic secretions can be seen – white blobs
- In some cases, prostatic concretions can be seen – these are spherical structures that are formed from concentric layers of condensed secretions
– darker blobs near the secretions – in the same white blob but a darker bit (they’re aggregations of condensed of old prostatic tissue)
- They tend to increase in number with age and may become calcified
