DEN 110 Exam 2

The first signs of tooth are evident when the embryonic oral epithelium begins to thicken and forms the dental lamina; this is seen during the 6th embryonic week

What is the first sign of tooth development, and when is it seen?

Embryonic oral epithelium is stratified squamous epithelium

Oral epithelium is an example of what type of epithelial arrangement?

Ectodermal cells

The enamel organ comes from what germ layer?

Bud stage
- 1st stage of development of enamel organ
- Cells stretch out from dental lamina as they grow and parts of the bud become slightly concave

Cap stage
- Formation and separation of the OEE, IEE, and stellate reticulum

Bell Stage
- Development of stratum intermedium
- Formation of the outline of a tooth crown and production of enamel

What are the stages of the enamel organ and what changes take place?

Ectodermal dysplasia is a condition in which there is poor development of structures arising from ectoderm, such as sweat, salivary, and sebaceous glands, skin, hair, and the enamel of teeth. Because enamel is also formed from ectoderm, it can also be affected by ectodermal dysplasia

What is ectodermal dysplasia, and what is the significance of the origin of the enamel
organ in relation to this pathologic condition? Besides enamel, what other structures
develop abnormally from this condition?

1. OEE can be considered a protective layer for the entire enamel organ. Later it will play
a role in attaching the gingiva to the tooth.
2. The cells of the IEE elongate and change internally to become ameloblasts, which
are responsible for actual enamel formation.
3. The stellate reticulum functions as a cushioned protection for IEE cells and plays
some role in nourishment of the stratum intermedium by allowing vascular fluids to move
between the loosely packed cells.
4. The cells of the stratum intermedium probably help provide nourishment for IEE cells.
They are also producers of protein and may receive products from and provide products
for the ameloblasts

What are the four layers of the enamel organ as seen in the bell stage, and what is their
function?