| Popis: |
During successive growth stages in the human embryo, the basal cells of the developing epidermis and specific areas of the oral mucous membranes are observed to be one of two types. One type is represented by a cuboidal cell which contains a large, round nucleus which occupies the majority of space in the cell. The cytoplasm of this cell is granular and slightly eosinophilic. This basal cell is located in the oral epithelium of the lips, cheeks, and soft palate. The other cell type is represented by a tall columnar cell which is polarized by the presence of an oval nucleus in the pole of the cell furthest away from the cell border in contact with the mesenchyme. The polarization produces a clear zone in the cell which is due to the fact that most of the cytoplasm appears to be missing. Small amounts of cytoplasm are present in the cell in the form of fine granules and filaments. It is possible that the granules are filaments seen in cross section. It was impossible to determine this conclusively with the resolution of the light microscope. The polarized, columnar, basal cells were observed in the epithelium of the gum ridge, hard palate, and epidermis. The speculation was offered that the morphologic difference in the basal cells in areas destined to become masticatory and lining mucosa in the adult, may be a reflection of a genetic bias of these tissues to develop along predetermined pathways to become a cornified or a non-cornified stratified squamous epithelium. The differentiation may initially take place at the same time oral mucosa is differentiated to become dental lamina. |
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