Lab 2 Epithelial Tissue: Index - 1)Introduction - 2)Simple Squamous - 3)Simple Cuboidal - 4)Simple Columnar - 5)PsuedoStratified - 6)Transitional - 7)Stratified Squamous - 8)Stratified Columnar - 9)Stratified Cuboidal - 10) Trachea and Esophogus Comparison - 12) Practical

STRATIFIED SQUAMOUS EPITHELIUM

Uppermost cellular layer composed of squamous epithelium, may be many layers thick.

1. Surface of Tongue moist (non-keratinized), papillated

# 96 - Tongue, circumvallate papillae, h&e

Locate the darker staining band of tissue that borders this section. The surface of the tongue is covered with a stratified squamous epithelium of many layers of cells. Note mitotic figures in the basal layers. Note the cytomorphosis (change in cell shape) from the bottom basal layer to the top layer.

References: Gartner, p. 269, Fig. 1 - 2 Wheater, p. 243, Fig. 13.12 DiFiore, p. 155, Fig. 11-3

2. Lining of esophagus non-keratinized, papillate

# 106 - Esophagus, upper, monkey, c.s., h&e

If needed, # 213 - Esophagus, rabbit, 1.5 mm, h&e

Note the extremely thick lining of the esophagus. What function does this thick layer serve? The esophagus is lined with non-keratinized stratified squamous epithelium. Note the persistence of nuclei even in the top layers of this epithelium.

References:Gartner, p. 281, Fig. 1 - 2 Ross, p. 475, Fig. 2 DiFiore, p. 13, Fig. 1-5 Wheater, p. 249, Fig. 14.2a

Esophagus Epithelium

3. Corneal epithelium non-papillated

# 199 - Eye, h&e

Again examine the slide first by eye, and then by scanning lens (4X) to get oriented. Find the big pink oval (the lens). In front of the lens, above the pigment layer is the cornea. Observe this outermost layer of the eye. This is the corneal epithelium which consists of 4 - 6 rows of non - papillated stratified squamous epithelium. Contrast its even appearance with the wavy lining of the esophagus.

References: Ross, p. 766, Fig. 1 Gartner, p. 389, Fig. 1 Wheater, p. 386, Fig. 21.15 DiFiore, p. 333, Fig. 20-3

Corneal Epithelium

4. Skin keratinization

# 9 - Skin, monkey, h&e papillated

# 11 - Skin of palm, human, h&e, 1.5 mm

Again examine by eye and find the purplish edge to the section. This is the epithelial layer. In the skin, the outermost cells have lost their nuclei and are keratinized. Compare this section to the previous one of the esophagus. The skin has an outer keratinized layer and thin skin has fewer epithelial layers than that of the esophagus. The skin of the palm has almost as many layers of epithelial cells as the esophagus, but the top layer of the palm skin has no nuclei remaining, i.e., it is keratinized, consisting of dead cells.

What function(s) does this keratinized layer serve?

Note the papillated layer of underlying connective tissue. What is the difference in the appearance of this layer in thin skin compared to that in thick skin?

References: Gartner, p. 35 , Fig. 3,p. 225, Fig. 1 p. 227, Fig. 2 Wheater, p. 153, Fig. 9.1 p. 211, Fig. 1 p. 154, Fig. 9.2 p. 213, Fig. 2 Ross, p. 392 - 393, Fig. 1 - 3 DiFiore, p. 139, Fig. 10-2