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Ameloblasts form conical projections, known as Tomes’ processes in
A. Inductive stage
B. Organizing stage
C. Formative stage
D. Protective stage
Tomes’s processes are those projections and give the ameloblast a ——————– under a microscope.
A. “sine-wave” appearance
B. “saw-tooth” appearance
C. “picket-fence” appearance
D. “soap-bubble” appearance
Life cycle of ameloblasts consists of six stages:
- Morphogenic stage
- Organizing stage
- Formative (secretory) stage (Tomes’ processes appear)
- Maturative stages
- Protective stage
- Desmolytic stage
| Life cycle of ameloblasts consists of six stages | Important Changes | |
| 1 | Morphogenic Stage | Morphology of the cell is short, columnar with large oval nuclei. |
| 2 | Organizing Stage | Nnucleus migrates towards the proximal end.In contrast to this, golgi apparatus and centrioles migrate towards the distal end.This change is referred to as “REVERSAL OF POLARITY” |
| 3 | Formative Stage | Formation of enamel matrix begins |
| 4 | Maturative Stage | Mineralisation of enamel takes place which is known as maturation |
| 5 | Protective Stage | Enamel is completely developed and fully calcified |
| 6 | Desmolytic Stage | Reduced enamel epithelium releases enzymes which destroy the connective tissue this process is known as desmolysis |
Ameloblasts
Ameloblasts are cells which secrete the enamel proteins enamelin and amelogenin which will later mineralize to form enamel, the hardest substance in the human body.
Striae of Retzius
Striae of Retzius are incremental growth lines or bands seen in tooth enamel.
They represent the incremental pattern of enamel, the successive apposition of different layers of enamel during crown formation.
There are 3 types of incremental lines:
- Daily incremental lines (cross striation),
- Striae of Retzius
- Neonatal lines.
Neonatal line
Neonatal line is a histologic landmark in primary tooth enamel corresponding to the event of birth.
Neonatal line is caused by the effect of metabolic stress on tooth structures when the fetus passes to extrauterine life.
Tomes’s processes
Tomes’s processes are a histologic landmark identified on an ameloblast, cells involved in the production of tooth enamel.
