Lab 11 Integumentary System: 1) Index 2) Introduction 3) Things to identify 4) Thick Skin 5) Thick Skin II 6) Thin Skin 7) Pigmented Epithelium 8) Lower Lip 9) Apocrine Sweat Glands 10) Nail Developement 11) Comparisons 12) Practical

 

Lower Lip

 

# 15 - Lower lip, human fetus, h - e, entire thickness

 

In humans, the inner surface of the lip is non-keratinized and consists of stratified squamous epithelium which is kept moist within the mouth. The outer surface exposed to the atmosphere has a clearly defined keratin layer, together with hair follicles and sebaceous glands. Under the epithelium is a richly vascularized dermis. The skeletal muscle that runs through the center of the tissue of the lip is the orbicularis oris.

What accounts for the redness of the lips at the the vermilion border? The epithelium of this richly vascularized region is only lightly keratinized. This area also has rich sensory innervation, but no sweat or sebaceous glands.

Reference: DiFiore, p. 150 - 151, Fig. 11 -1 Wheater, p. 235, Fig. 13.1

 

This is a low power shot of the Lip. The blue arrows are pointing to the epithlium that is Stratified Squamous Keratinized. This is located facing the outside environment. The red arrows are pointing to the epithelium of the lip that is Stratified Squamous Non-Keratinized and is found facing the internal environment of the oral cavity.

Red arrows - Stratified Squamous Non-Keratinized

Blue arrow - Stratified Squamous Keratinized

 

 

Here is a closer look at the lip. The blue arrow is pointing the part in the lip called Vermillion border. It is the border between where the stratified squamous keratinized meets the non-keratinized. The red arrow is pointing out the area of the lip where the epithlium is non-keratinized. Can you see how the nuclei go all the way to the top? The green arrows are poining to a few of the many arteries that are really close to the surface which give the lip it's red color.

Blue arrow - Vermillion Border

Red arrow - Stratified Squamous Non-Keratinized

Green arrow - Arteries

 

 

 

The Lip

Lip (high power)