Question

Describe the histology of the urinary tract and how that changes between the ureter and the renal tubules.

Answer 1

The urinary tract includes the ureter, urinary bladder and urethra.

It conducts urine from the kidneys to the outside world.

The urinary tract is lined by a highly stretchable and impermeable epithelium known as the urothelium, specialized for the task of urine conduction.

Histology of urinary tract:-

• The ureters and the urinary bladder is lined by transitional epithelium. The features of transitional epithelium are:-

1. Surface cells are umbrella-shaped
2. Bi-nucleated (sometimes)
3. Eosinophilic glycoprotein coat (impermeable to urine)
4. Connected to one another by desmosomes
5. Surface cells alter thickness during distension

• HISTOLOGY OF URETERS:-

1. Star-shaped lumen

2. Made up of 4 layers:-

(a) Adventitia coat (fibrous)

(b) Muscular coat (Smooth muscle) -produce peristalsis

• Outer circular
• Inner longitudinal

(c) Lamina propria

(d) Mucous membrane

• HISTOLOGY OF URINARY BLADDER

Made up of 4 layers:-

(a) Outer adventitia coat

(b) Muscular coat (Smooth muscle)

• Outer longitudinal
• Middle circular
• Inner longitudinal

(c) Lamina propria

(d) Mucosa (mucosal layers are 6-8 layer thick)

Whereas, histology of renal tubules is as follows:-

1. Proximal convoluted tubule- Simple tall cuboidal epithelium, with a brush border (microvilli). The epithelium almost fills the lumen, and the microvilli increase the surface area by 30-40 fold.
2. Loop of Henle- Made up of simple squamous epithelium.
3. Distal convoluted tubule- The epithelial cells are cuboidal, with very few microvilli.
4. Collecting duct- The epithelium of these tubules consist of cuboidal or columnar cells. They have large lumens.