Histology

Lymphoid organs

Endocrine

Electron microscope

Muscles

Cartilages

 

Connective tissues

Respiratory tract

• Respiratory Epithelium Types

Location	Epithelium Type
Nasal mucosa till Proximal bronchiole	Pseudostratified ciliated columnar epithelium
Terminal bronchiole	Ciliated cuboidal epithelium • No goblet cells • Epithelium change • No hyaline cartilage from here
Respiratory bronchiole	Non-ciliated cuboidal epithelium
Alveolus	Simple squamous epithelium

Urogenital system

Transitional epithelium / urothelium lines

• Renal pelvis and calyces,

• ureter

• urinary bladder

• pre-prostatic & prostatic parts of the urethra

Kidney

Pancreas

Common Confusions

• Can be confused with kidney
• Islet of pancreas may resemble Bowman’s capsule at low power.

• Can be confused with parotid gland
• Due to presence of serous acini.

Exocrine Part – Acini

• Presence of asinus (acini).

• Acinar cell features:
• Rounded nucleus.
• Basophilic cytoplasm.
• Basophilia more on basal side.
• Zymogen granules in apical region.

• Key Differentiating Feature
• Centroacinar cells (most important):
• Pale staining cells.
• Seen inside the acinus.
• Not seen in serous glands like parotid.
• Parotid shows only peripheral acinar cells.

Endocrine Part – Islet of Langerhans

• Appears as a lightly stained (pale) area.

• Can mimic Bowman’s capsule at low magnification.

• Predominantly present in the tail of pancreas.

Cell Arrangement in Islet

• Beta cells:
• Located centrally.
• Majority cells.
• ~75% (3/4) of islet cells.

• Alpha cells:
• Located peripherally.

• Delta cells:
• Located peripherally.
• Least numerous.
• ~6–8% of total cells.

• H&E stain:
• Alpha, beta, delta cells cannot be differentiated morphologically.
• Identification based on location and proportion.