The Formation of Epidermal Cell Columns

Abstract

Factors related to the formation of epidermal cell columns were investigated in skin sections which had been expanded and stained with fluoresceine-isothiocyanate of prepared for electron microscopy and electron microscopical autoradiography. An analysis was also made of the epidermal proliferative rate in mouse ear and sole and guinea-pig ear. All these methods showed that, in epidermis which is organized into cell columns, the cornification process does not occur synchronously in adjacent stacks. Cornification occurs alternately from one column to the next so that the newest cornified cell is found in the lowermost (down) position, and in consequence there are fewer living cells in this stack. Further flattening, due possibly to the loss of turgidity and cellular contents in the newly cornified cell, apparently results in an overall reduction of pressure in this column. It is then possible for the most mature basal cell to slide from the basal layer and position itself in this column. Evidence for the movement of maturing basal cells in this way was demonstrated by staining with fluoresceine-isothiocyanate. It was also found that column formation was associated with a low rate of new cell production. Where the new cell production exceeds one cell per day per corneocyte, cell production. Where the new cell production exceeds one cell per day per cornepcute, cells of the same age and hence maturity are in competition, and a disorganized arrangement occurs. It is concluded that the low cell production and hence the differences in degree of maturation of neighboring cells in adjacent stacks are directly responsible for the columnar organization of epidermis in certain body sites.