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HISTOLOGY REVIEW Epithelia. Dr. Tim Ballard Department of Biology and Marine Biology. Simple squamous epithelium. Kidney – median sagittal section – H&E – 10x objective.

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HISTOLOGY REVIEW Epithelia

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Histology review epithelia

HISTOLOGY REVIEWEpithelia

Dr. Tim Ballard

Department of Biology and Marine Biology


Histology review epithelia

Simple squamous epithelium

Kidney – median sagittal section – H&E – 10x objective

Arrowheads indicate the locations of Bowman’s capsules within the cortex of the kidney. This is one place to locate simple squamous epithelium.


Histology review epithelia

Simple squamous epithelium

Kidney – median sagittal section – H&E – 40x objective

lumen

Bowman’s capsule

Single layer of flattened cells with prominent flattened nucleus, very thin, lining the capsular space of Bowman’s capsule


Histology review epithelia

Simple squamous epithelium

Artery – cross section – H&E – 40xobjective

lumen

Flattened cells, one cell layer thick, lining the lumen of an artery


Histology review epithelia

Simple cuboidal epithelium

Kidney – median sagittal section – H&E – 10xobjective

Arrowheads indicate renal tubules in the kidney cortex. “Tubule” is a key word, telling you this is one place to locate simple cuboidal epithelium.


Histology review epithelia

Simple cuboidal epithelium

Kidney – median sagittal section – H&E – 40xobjective

lumen

Approximate location of basement membrane

lumen

Approximate size of one cell

Renal tubules (arrowheads) – note that the cells appear about as tall as they are wide and that there is a single layer of cells.


Histology review epithelia

Simple cuboidal epithelium

Kidney – median sagittal section – H&E – 40xobjective

lumen

In the renal medulla you find collecting ducts, lined with a single layer of simple cuboidal cells.


Histology review epithelia

Simple cuboidal epithelium

Thyroid gland – cross section – H&E – 40xobjective

lumen

lumen

Simple cuboidal epithelium (arrowheads) forms follicles in the thyroid gland.


Histology review epithelia

Simple cuboidal epithelium

Pancreas – section – H&E – 40xobjective

lumen

Duct (arrowhead indicates location of the basement membrane) within the pancreas. Note the single layer of simple cuboidal cells.


Histology review epithelia

Simple columnar epithelium

Gallbladder – section – H&E – 10xobjective

lumen

Villi (arrowheads) – finger-like processes inside the gallbladder. This organ of the digestive system is line with simple columnar epithelium.


Histology review epithelia

Simple columnar epithelium

Gallbladder – section – H&E – 40xobjective

Basement membrane would be located along this line.

Approximate size of one cell

lumen

Note that the simple cuboidal cells are taller than they are wide.


Histology review epithelia

Simple columnar epithelium

Duodenum – section – H&E – 40xobjective

Approximate size of one cell

Basement membrane would be located along this line.

lumen

Although this looks different from the gallbladder, this is still simple columnar epithelium.


Histology review epithelia

Ciliated pseudostratified columnar epithelium

Trachea – cross section – H&E – 10xobjective

lumen

epithelium

Basement membrane would be located along this line.

Underlying connective tissue

This is the signature epithelium of the respiratory system. Note the difference between epithelium above and connective tissue below the line.


Histology review epithelia

Ciliated pseudostratified columnar epithelium

Trachea – section – H&E – 40xobjective

lumen

cilia

Basement membrane

All cells contact the basement membrane, but not all cells reach the surface. It only appears stratified, hence the name.


Histology review epithelia

Ciliated pseudostratified columnar epithelium

Intrapulmonary bronchus – section – H&E – 40xobjective

lumen

cilia

Basement membrane

You can tell this isn’t stratified columnar epithelium because no can’t discern individual layers. Stratified columnar would have clear rows of nuclei.


Histology review epithelia

Stratified squamous epithelium

Esophagus – section – H&E – 10xobjective

lumen

How many layers of cells do you see here?

Basement membrane

Underlying connective tissue

It is easy to see why this is called a stratified epithelium. I counted about 35 layers of cells stretching from the basement membrane to the apical surface.


Histology review epithelia

(nonkeratinized) Stratified squamous epithelium

Esophagus – section – H&E – 20xobjective

lumen

Basement membrane

Cells at the basal surface are cuboidal and mitotic. As new cells are pushed to the top, they become increasingly squamous in shape.


Histology review epithelia

Keratinized stratified squamous epithelium

Human skin – section – H&E – 10xobjective

Keratinized layers of cells

free surface

Basement membrane

Again, look at the layers of cells between the basement membrane and the apical surface.


Histology review epithelia

Keratinized stratified squamous epithelium

Human skin – section – H&E – 40xobjective

Keratinized layers of cells – very long, thin and flattened (scale-like)

Free surface

Epithelium

Basal surface

Cuboidal cells at the basal surface give way to increasingly flattened cells (squamous) in the upper layers. The cells are filled with water-proof keratin.


Histology review epithelia

Stratified cuboidal epithelium

Submandibular (salivary) gland – section – H&E – 40x objective

Basal layer of cells

Approximate size of one apical cell

lumen

Apical layer of cells

Larger ducts of the body may have a stratified cuboidal epithelium, where the top layer of cells is cuboidal. There are usually only two layers of cells.


Histology review epithelia

Stratified columnar epithelium

Submandibular (salivary) gland – section – H&E – 40x objective

lumen

Apical layer of cells

Approximate size of one apical cell

What is the epithelial type?

Basal layer of cells

Very large ducts of the body may have a stratified columnar epithelium, where the top layer of cells is columnar. There are usually only two layers of cells.


Histology review epithelia

Transitional epithelium

Ureter – cross section – H&E – 10x objective

lumen

Epithelial layer

Underlying connective tissue layer

Basal layer of cells

Transitional epithelium is the signature epithelium of the urinary tract. It is found in the ureters and urinary bladder.


Histology review epithelia

Transitional epithelium

Ureter – cross section – H&E – 40x objective

lumen

Apical layer of cells

Basal layer of cells

When the organ walls are under low tension, the epithelium has 6 – 8 layers of cells.

This is called transitional epithelium because the number of cell layers changes as the organ walls increase and decrease in tension.


Histology review epithelia

Transitional epithelium

Urinary bladder – section – H&E – 10x objective

lumen

Basement membrane

The urinary bladder looks different from the ureter because it is a different organ with different function, but the epithelium is still transitional.


Histology review epithelia

Transitional epithelium

Urinary bladder – section – H&E – 40x objective

Apical layer of cells

lumen

Basal layer of cells

Basement membrane

The distinguishing features of this epithelium are multiple layers and the very large “sofa pillow-like” cells at the apical surface.

end


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