Pl. IV · Stratifex squamosus — stratified squamous

The plate

The specimen, drawn

Pl. IV

The tissue as you will meet it on the slide.

Habitat & range

Where it lives

Body map

Where this tissue is found.

Range

• Epidermis
• Oral cavity, pharynxThe muscular passageway connecting the mouth to the esophagus and larynx., oesophagus
• Anal canal
• Vagina
• Cornea

Collection record

• Add your slide numbers here.

Niche

What it does for a living

Wear and replacement. It expects to lose its surface and is built to keep replacing it from below. Protection, not exchange — nothing useful crosses this tissue quickly, which is exactly the point.

field collected specimen

How to know it on sight

• Many layers, and the cellsThe basic structural and functional units of life. change shape as you climb.
• Cuboidal and busy at the bottom, polygonal in the middle, flat and dying on top.
• Named for the top layer, not the bottom.
• Keratinised where it is dry; still nucleated where it is wet.

Specimen 1

Specimen 2

Specimen 3

People keep calling her by the wrong name

Look-alikes

Three plates. Read the line underneath each one before you decide.

Transitional

Tell them apart by the top row and the address. Transitional domes rather than flattens, and lives only in the urinary tract.

Stratified cuboidal

Tell them apart by depth. Two layers with square top cells, not a thick stack of flattening ones.

Pseudostratified

Tell them apart by tracing cells down. If every one reaches the membrane it was never stratified.

Examine it yourself

The virtual slide

Zoom in until you can see the surface of the cells, then find the basement membrane underneath.

Virtual slide courtesy of Histology Guide.

Field notes

Why this animal

A pangolin’s scales are keratinA strong, fibrous protein that forms the structure of skin, hair, and nails., laid down at the baseA substance that accepts hydrogen ions (H⁺) or releases hydroxide ions (OH⁻). and worn away at the tip. It is wearing the tissue on the outside.