|Pathbase Image PB 24089 submitted by University of Cambridge on 2003-11-01|
|EMAP / Embryonic stage, |
tissue or post-natal age:
|99994 - Newborn|
|Genotype Status:||Wild-type |
|MPATH / Pathology:||MPATH 458 - normal|
|Genetic Manipulation:||None |
|MA / Anatomical Site:||MA 1602 - lower jaw molar|
|Designated Allele Name:|
|Description:||Formation of lower jaw third molar. This is the smallest of the third molars as well as the one that develops last. While tooth bud formation of the first molar is initiated at E14, the third molar reaches a similar stage of development at 4-6 days post-natally. Thus eruption of the first molar is complete by three and a half weeks of age while the third molar only reaches functional occlusion by seven weeks of age.|
At this stage of development only the coronal portion of the tooth has formed towards the top of the image the tooth is limited by inactive ameloblasts, while on either side of the crown the ameloblastic layer is characterised by highly cylindrical cells with basally located nuclei. The enamel still mainly consists of unmineralised enamel matrix, the main component of this being amelogenin. The pulpal cavity is limited by an odontoblastic layer bordering on dentine, the pale zone closest to the cells being pre-dentine, while the more basophilic zone is mature mineralised dentine.
At the lower left apical part the Hertwig root sheath is present.
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