Simple Epithelium: Features and Locations
Features | Simple Squamous | Simple Cuboidal | Simple Columnar |
Length : Breadth of cell | Length < Breadth | Length = Breadth | Length > Breadth |
Nucleus | Flat | Round | Elongated |
Function | Exchange | Secretion | Secretion |
Seen in | (3BA) | (TOK) | ㅤ |
ㅤ | • Bowman's capsule • Blood vessel • Body cavities • Alveoli | • Thyroid follicles • Germinal epithelium of Ovary | • Stomach • Large intestine • Uterus |
Compound/Stratified Epithelium
Features | Stratified squamous | Stratified cuboidal | Stratified columnar |
Apical layer | Squamous | Cuboidal | Columnar |
Intermediate layer | Polygonal cells | Polygonal cells | Polygonal cells |
Basal layer | Columnar cells | Columnar cells | Columnar cells |
Seen in | • Skin • Tongue • Tonsils • Esophagus • Lower part of anal canal • Vagina | • Exocrine glands • Sweat glands | • Membranous & • penile urethra |
ㅤ | Remember the sensitive areas in me and ToEs (+Tonsil and esophagus) | Cub sweat excessively | ㅤ |
Transitional epithelium / urothelium lines
- Renal pelvis and calyces,
- ureter
- urinary bladder
- pre-prostatic & prostatic parts of the urethra
Pseudostratified Columnar Epithelium
- All cells rest on basement membrane.
- Nuclei at different levels.
- Appears stratified; actually simple.
- Often ciliated -respiratory tract
- Nose:
- Vestibule:
- Lined by stratified squamous epithelium.
- Has hair follicles.
- Rest of the nose:
- Lined by Respiratory epithelium
- Pseudostratified ciliated columnar epithelium
- Also known as Schneiderian membrane.
Epithelium | Found in |
Simple ciliated columnar Epithelium | • Eustachian tube. • Middle ear. • Ventricles of brain. • Fallopian tube. |
Pseudostratified Ciliated Columnar Epithelium | • Respiratory epithilium • Membraneous Urethra • Spongy Urethra |
Epithelium vs. Epithelioid
- Epithelium:
- Covers outer body, lines organs/glands.
- Epithelioid Cells
- Derived from activated macrophages that originally had a free surface.
- They lose the free surface.
- They retain the basement membrane–like support.
- Examples SEAL 123
- S – Sebaceous gland
- E – Epithelioreticular cells (thymus)
- A
- Adrenal gland parenchyma
- Anterior pituitary
- L
- Leydig cells (testis)
- Lutein cells (ovary)
- Langerhans cells (pancreas)
Endothelium and Mesothelium
Endothelium
- Lines blood and lymphatic vessels.
- Simple squamous.
- Exception
- Cuboidal epithelium with central round nucleus.
- High Endothelial Venules (HEVs)
- In lymphoid organs - Spleen
Mesothelium
- Covers closed body cavities.
- Simple squamous.
GIT
Oral Cavity
- Masticatory mucosa
- Gingiva
- Hard palate
- Keratinized or Parakeratinized
- Lining mucosa
- Lips
- Cheek
- Soft palate
- Non-keratinized
- Exception: Vermilion border is Keratinized
- Specialized mucosa
- Dorsum of tongue
- Non-keratinized
- Exception: Filiform papillae are Keratinized
Teeth (Enamel)
- Derived from epithelium via ameloblasts (coloumnar epithelium)
Anal Canal
- Upper 2/3 from endoderm (primitive rectum)
- Lower 1/3 from ectoderm (Anal membrane)
- Dentate line marks the junction
Liver
Classical/ Hepatic lobule
- ZONES OF LIVER
- Zone 1: Periportal.
- Zone 2: Midzonal.
- Zone 3: Centrilobular.
- Most susceptible to ischemia.
Tounge
Salivary Glands
Mucous Acini
- Mucous acini:
- Columnar cells
- Clear cytoplasm
Serous acini:
- Pyramidal cells
- Round basal nuclei
- Apical granules, stain darkly
Made with Bullet