Kinetics of the inner enamel epithelium in the adult rat incisor. II. Computer model.

Abstract

ABSTRACTThe inner enamel epithelium (IEE) in the model consists of a 1500 cell matrix. Cells formed on the apical side of the matrix proliferate and migrate towards its incisal (or distal) end, where they are shed. the continuous cell supply is maintained by two types of cell: (a) the blasts, which preserve their physical position in the matrix. Upon division, the blast yields one blast, occupying the space of the mother cell, and a migrating metablast. (b) the metablasts, which divide while migrating along the matrix. Each blast division forms a metablast clone whose size depends on the number of divisions its members undergo. the metablasts finally mature and cease to divide.Each cell is described by three attributes which change with time: age, label content and the number of divisions it underwent since the metablast clone was formed. (This attribute is set to zero in the blasts.)The system is governed by the following parameters: (a) the size of the blast compartment. (b) the number of divisions a metablast clone undergoes in its life time. (c) the lengths of the phases in the cell cycle. (d) the length of the time unit. (e) Degree of variation in the system (noise).In the experiments described only one set of parameters was used: tc= 22 hr, tG1= 12.5 hr, ts= 7 hr, tG2= 2 hr, tm= 30 min, variation = 20%.The model mimics well experimental results reported before, such as the migration rate of labelled cells on the IEE axis and labelled mitosis curve. It predicts new facts like changes in the grain count and labelled cell index with time.