Amelogenesis Oral Histology Ass. Prof. Dr/ Baleegh A. Alkadasi
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Amelogenesis
-Process of enamel formation by ameloblast cells.
-The ameloblast begin enamel deposition after a few micrometers of dentin deposited at
DEJ.
- At the bell stage, cells of inner enamel epithelium differentiate to form the ameloblast.
-The ameloblast elongate and are ready to become active secretory ameloblasts.
Histology of Ameloblast:
-Tall columnar cell, 4 – 5 microns in diameter and about 40
microns in length.
-in cross section they assume a hexagonal shape.
- Golgi’s apparatus appears centerally in the ameloblast and
amount of rough-surfaced endoblasmic reticulum increase
in apical area.
- The row of ameloblast maintains the orientation by cell to
cell attachment (desmosomes) at the proximal and distal
ends of the cell. This maintains the cells in the row as they move periphery from DEJ.
- Short conical process (Tome’s process) develops at the apical end of the ameloblasts
during the secretory stage.
83
, Amelogenesis Oral Histology Ass. Prof. Dr/ Baleegh A. Alkadasi
-----------------------------------------------------------------------------------------------------------------------------------------------------
- There is Junctional complex at the end and at the junction of adjacent ameloblast and
Tome’s processes called terminal bar apparatus, this maintain contact between adjacent
cells.
-The amelogenesis divided into two stages:
1-Formation of enamel matrix.
2- Enamel Mineralization
-The two processes of Matrix formation & Mineralization takes place at same time.
-Enamel crystals appear in newly secreted enamel matrix
-Both organic & inorganic materials are secreted together from the ameloblasts as
enamel matrix.
1. Formation of enamel matrix:
-Synthesis of enamel protein occur in R.E.R ( Rough Endoplasmic Reticulum ) then
passes to G.C (Golgi Complex ) in which it is condensed & Polysaccharide fraction is
added & packed into membrane bound secretory granules.
- These granules migrate to the distal extremity of the cell & their content are released
against the newly formed dentine.
-Little (if any) time intervals exist between the secretion of enamel protein and appearance
of inorganic crystals.
-Small isolated areas of unmineralized enamel matrix called stippled material.
84
-----------------------------------------------------------------------------------------------------------------------------------------------------
Amelogenesis
-Process of enamel formation by ameloblast cells.
-The ameloblast begin enamel deposition after a few micrometers of dentin deposited at
DEJ.
- At the bell stage, cells of inner enamel epithelium differentiate to form the ameloblast.
-The ameloblast elongate and are ready to become active secretory ameloblasts.
Histology of Ameloblast:
-Tall columnar cell, 4 – 5 microns in diameter and about 40
microns in length.
-in cross section they assume a hexagonal shape.
- Golgi’s apparatus appears centerally in the ameloblast and
amount of rough-surfaced endoblasmic reticulum increase
in apical area.
- The row of ameloblast maintains the orientation by cell to
cell attachment (desmosomes) at the proximal and distal
ends of the cell. This maintains the cells in the row as they move periphery from DEJ.
- Short conical process (Tome’s process) develops at the apical end of the ameloblasts
during the secretory stage.
83
, Amelogenesis Oral Histology Ass. Prof. Dr/ Baleegh A. Alkadasi
-----------------------------------------------------------------------------------------------------------------------------------------------------
- There is Junctional complex at the end and at the junction of adjacent ameloblast and
Tome’s processes called terminal bar apparatus, this maintain contact between adjacent
cells.
-The amelogenesis divided into two stages:
1-Formation of enamel matrix.
2- Enamel Mineralization
-The two processes of Matrix formation & Mineralization takes place at same time.
-Enamel crystals appear in newly secreted enamel matrix
-Both organic & inorganic materials are secreted together from the ameloblasts as
enamel matrix.
1. Formation of enamel matrix:
-Synthesis of enamel protein occur in R.E.R ( Rough Endoplasmic Reticulum ) then
passes to G.C (Golgi Complex ) in which it is condensed & Polysaccharide fraction is
added & packed into membrane bound secretory granules.
- These granules migrate to the distal extremity of the cell & their content are released
against the newly formed dentine.
-Little (if any) time intervals exist between the secretion of enamel protein and appearance
of inorganic crystals.
-Small isolated areas of unmineralized enamel matrix called stippled material.
84
