Lab 18 Oral Cavity and Salivary Glands: 1) Index 2) Introduction 3) Things to Identify 4) Hard Palate 5) Soft Palate 6) Tonsils 7) Tongue 8) Parotid Glands 9) Submandibular Glands 10)Sublingual Glands 11) Comparison of Structures 12) Practical

 

The Tongue

 

# 94 - Tongue, filiform papilla, 1.5 mm, h-e

# 96 - Tongue, circumvallate papilla, 1.5 mm, h-e

# 95 - Tongue, fungiform papillae, human, 1.5 mm, h-e

 

The thick stratified squamous epithelial covering of the tongue is unkeratinized except for one type of lingual papillae. Which lingual papilla is covered with keratinized epithelium?

Note the lamina propria of loose connective tissue, the submucosa, and the musculature of the tongue. Vertical, transverse and longitudinally sectioned skeletal muscle fibers are intricately interwoven. This interwoven pattern allows the tongue complex movements.

How much vascular and nervous support would you expect for this highly muscular organ? Identify the various types of lingual papillae after consulting your text as to their distribution on the tongue. Look for filiform, fungiform and circumvallate papillae on these slides. See your atlas for typical morphology of each and look for them on your slides. Look for tastebuds alongside of the clefts in the circumvallate papillae. See if you can identify the darker Type I (support) and the clear Type 2 (neuroepithelial or sensory) cells as well as the basal cells that are positioned near the basement membrane. Try to find a taste pore , the hole by which taste buds communicate with the surface.

Types of lingual papillae:

1. Filiform papillae - These conical papillae are the most numerous. Each consists of a long, slender core of connective tissue covered by epithelium. They are keratinized on their tips. They have no tastebuds associated with them.

2. Fungiform papillae - Somewhat resemble a mushroom of the common edible variety. They are broad and round and non-cornified, with 1 - 5 tastebuds associated with them. Their epithelium overlies a core of lamina propria.

3. Vallate (or circumvallate) papillae - are surrounded by a deep furrow. Serous glands (von Ebner's glands) open into the bottom of the furrow and taste buds line the furrow. The"moat" around the circumvallate papilla is filled with secretions from these glands .

4. Foliate papillae - Well developed in some mammals (especially rabbits), foliate papillae are rudimentary in adult humans. They contain many taste buds.

REFERENCES: Gartner, p. 268-267 Ross, p. 426 - 429 Wheater, p. 374. Fig. 21.1 DiFiore, p. 153 - 157, Fig. 11-2 - 11-4

 

This is an image taken from the surface of the Tongue. In this image you can see two of the four lingual papillae. The blue arrows are pointing to the most abundant lingual papillae called Filliform papillae. Filliform papillae are KERATINIZED and HAVE NO TASTE BUDS. These are two important facts to keep in mind. The other type seen in this image is the Fungiform Papillae, (red arrow) which in this section is just coming into view. Fungiform papillae are NOT KERATINIZED and has a shape like a mushroom, hence the name 'fungiform'. There may or may not be taste buds found on Fungiform papillae. They are also the second most numerous.

Blue arrows - Filliform papillae

Red arrow - Fungiform papillae

 

 

Here is a similar image with both lingual papillae present in it. The blue arrow is pointing to a Filliform papillae. Notice the 'coming to a point' characteristic of the filliform papillae. This is a good clue to help identify the filliform papillae. The red arrow is pointing to a Fungiform papillae. In this view, you can really get a good idea of the 'mushroom' shape of these papillae. Remember these are not Keratinized or Cornifies, and may have taste buds on them.

Blue arrow - Filliform papillae

Red arrow - Fungiform papillae

 

 

 

 

This is an image of what is known as the Circumvallate papillae, indicated by the blue arrow. These are the largest of all papillae and the least number present on the tongue. It is surrounded by a Trench which the labels A are indicating. On the other side of the trench is a wall which the red arrow is pointing to. On the papillae side of the trench is where you would find an abundance of Taste Buds, which is what the green arrows are pointing to.

Blue arrow - Circumvallate Papillae

Red arrow - Wall surrounding papillae

Label 'A' - Trench surrounding papillae

Green arrows - Taste Buds

 

 

 

 

Here is a another look at the Taste buds, (blue arrows) which are found on the circumvallate papillae with in the trench. Notice the light staining pattern of them compared to the rest of the epithelium of the papillae.

 

Blue arrows - Taste Buds

 

 

Here is a high power shot of Taste Buds indicated by the red arrows. Taste buds are composed of three types of cells, 1) Type 1 supportive cells 2) Type 2 nueroepithelial cells and 3) Basal cells. Another structure of the taste bud is the Taste Pore,indicated by the blue arrow. This allows for the food particles, which are dissolved, to enter and interact with the nueroepithelial cells to stimulate taste.

Red arrows - Taste Buds

Blue arrow -Taste pore

 

Here is another look at the Trench (label A) of a Cirumvallate papillae. The black arrows are pointing out the Taste buds while the green arrow is pointing to the Wall that surrounds the papillae. Of interest is a gland which is found at the base of the trench called Von Ebner's Gland, indicated by the blue arrow. These secrete a watery secretion to both dissolve food particles so they can be taste and keep the trench clean by flowing upward and keeping it free of debris.

 

Label 'A' - Trench of Circumvallate Papillae

Black arrows - Taste buds

Green arrow - Wall of papillae

Blue arrow - Von Ebner's Gland

 

 

 

Filliform and Fungiform papillae

Filliform and Fungiform papillae

Circumvillate Papillae

Taste Buds

Taste Buds (taste pore)

Circumvillate papillae (trench structures)