PB 24089

Date

2003-11-01

Magnification

Stain

Haematoxylin

Author

University of Cambridge

Series

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.

MPATH / Pathology

MPATH 458 - normal

Gene

sex

Male

strain

C57BL/6 CRL

organism

Mouse

EMAP / Embryonic stage, tissue or post-natal age:

99994 - Newborn

genotype status

Wild-type

genetic manipulation

None

MA / Anatomical Site

MA 1602 - lower jaw molar

Designated Allele Name

Experimental Manipulation

Further info

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Copyright

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