Histology of the Urinary System

Question 1

Click on Answer for histological slides of the kidney.

Answer 1

[Slide 1] [Slide 2] [Slide 3] [Slide 4] [Slide 5] [Slide 6]

Question 2

Bowman’s capsule
The Bowman’s capsule has an inner layer and an outer layer. The outer layer is known as the parietal layer and is composed of ____(a)____ epithelium and the inner layer is called the visceral layer and is composed of cells known as ____(b)____, which are associated with and surround the capillaries of the glomerular tuft and form part of the filtration apparatus.

Answer 2

(a) simple squamous
(b) podocytes

Question 3

Bowman’s capsule
The site where afferent and efferent arterioles penetrate and exit from the parietal layer of the capsule is called the ____(a)____ pole. Opposite this site is the ____(b)____ pole of the renal corpuscle, where the proximal convoluted tubule begins.

Answer 3

(a) vascular
(b) urinary

Question 4

Distinguish between cortical nephrons and juxtamedullary nephrons.

Answer 4

Cortical nephrons make up the majority of nephrons within the kidney and are located mostly within the renal cortex. They have shorter loops of Henle that do not extend very far into the renal medulla. This makes them less involved in concentrating urine but still very effective at filtering blood and forming urine.

Juxtamedullary nephrons are fewer in number but play a crucial role in the kidney’s ability to concentrate urine. They are located near the corticomedullary junction, and their loops of Henle extend deep into the renal medulla. This allows them to create a high osmotic gradient in the medulla, which is essential for water reabsorption and urine concentration.

Question 5

State the function of podocytes.

Answer 5

Podocytes form part of the filtration barrier in the glomerulus, which filters blood to form urine. Their foot processes wrap around the capillaries and leave narrow gaps called slit diaphragms, which prevent large molecules like proteins from passing into the urine.
[Slide 1] [Slide 2]

Question 6

(a) Where are mesangial cells found?
(b) State the functions of mesangial cells.

Answer 6

(a) They are found in the mesangium of the glomerulus. [The mesangium is an area inside the glomerular capillary tuft but outside of the capillary lumen.]

(b) Functions:
⚚ Phagocytosis and endocytosis of trapped residues and aggregated proteins from the glomerular basement membrane and filtration slit diaphragm.
⚚ Maintaining the structure and function of the glomerular barrier.
⚚ Synthesis and secretion of a variety molecules such as interleukin I, PGE2 and platelet-derived growth factor, which play a central role in response to glomerular injury.
⚚ Modulation of glomerular distention.
⚚ Structural support to the podocytes through production of mesangial matrix.

[Slide 1] [Slide 2]

Question 7

Identify the slide and identify its key histological features: [Slide].

Answer 7

ureter
☛ presence of a mucosa, muscular layer and adventitia [absence of submucosa]
☛ the lumen is lined by transitional epithelium
☛ extensive lamina propria
☛ muscularis layer comprises of an inner longitudinal layer, middle circular layer and outer longitudinal layer [the outer longitudinal layer is present in the distal parts of the ureter]
☛ presence of nerves, blood vessels and lymphatics in the adventitia
☛ More slides: [Slide 2] [Slide 3] [Slide 4] [Slide 5]

Question 8

Identify the slide and identify its key histological features: [Slide].

Answer 8

urinary bladder
☛ presence of a mucosa, muscularis layer and adventitia/serosa
☛ the muscularis layer is known as the detrusor muscle. Its fibres have a randomized orientation. Contraction of this muscle compresses the bladder and forces urine into the urethra