Special Histology and Embryology: Practical Course - V. K. Napkhanyuk 2001

Sensory Organs
Organ of Taste

The ORGAN OF TASTE (organum gustus) is a collection of the so-called taste buds (caliculi gustatoriae) located within the Stratified Epithelium of the lateral walls of the vallate, foliate, and fungiform papillae of the human Tongue. A taste bud consists of 40–60 tightly packed Cells of three types (micrograph 8):

1) receptor cells, or gustatory sensory epitheliocytes (epiteliocytus sensorius gustasoriae), whose apical surface bears microvilli;

2) supporting epitheliocytes (epitheliocytus sustentans), featuring a large Nucleus, well-developed elements of the granular and agranular Endoplasmic reticulum, the Golgi apparatus, and bundles of tonofibrils. They surround and insulate the taste cells and nerve fibers;

3) basal epitheliocytes, located on the basement membrane; these are poorly differentiated cells that presumably give rise to the supporting and taste cells.

Slides for Examination

Slide 1. Taste buds of the foliate papilla of the tongue (Fig. 12).

Low magnification. Under low magnification of the Microscope, locate the Cytology/practical/100.html">Foliate papillae of the tongue and, within the thickness of their epithelium, find the ellipsoid bodies (taste buds).

High magnification. Examine the taste bud. Among the epithelial Cells of the taste bud are gustatory sensory epitheliocytes with Hair-like processes (microvilli) at the apical surface, along with supporting cells. The apex of the taste bud communicates with The surface of the tongue via the taste pore, which leads into a small depression known as the taste pit.

Label the following on the drawing: 1) stratified squamous epithelium of the papilla; 2) interpapillary space; 3) taste bud cells: a) supporting cells (lighter); b) gustatory cells (darker); c) microvilli.

Control Questions

1. Development of the organ of taste.

2. Structure and histophysiology of the taste bud.

3. Features of the microscopic and ultramicroscopic structure of gustatory sensory epitheliocytes.

4. Microscopic structure of supporting epitheliocytes.

5. Structural Features of basal epitheliocytes.

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Fig. 12. Taste buds of the foliate papilla. Hematoxylin and eosin staining. × 600:

1 — stratified squamous epithelium of the papilla; 2 — interpapillary space; 3 — taste bud cells (a — supporting cells (lighter); b — gustatory cells (darker); c — microvilli)

Situational Problems

1. Which taste sensations will be impaired if the taste buds at the ROOT of the tongue are damaged?

2. Which taste sensations will be impaired if the taste buds at the tip of the tongue are damaged?

Sample Examination Questions

1. Development, structure, and histophysiology of The Organ of taste.

Electron micrograph 8. Apical region of a taste bud. × 10,000:

1 — taste pore; 2 — microvilli of taste receptor cells (taste hairs); 3 — cellular filaments in the Cytoplasm of taste cells (from Rodin's atlas)