The epithelial tissues

Abstract

The way in which epidermal homeostasis is continually maintained by cellular responses to gradients of messenger molecules has been outlined, although the details of what is evidently a complex mechanism are not well enough known for final conclusions to be drawn. The question that now arises is whether this same type of chalone mechanism also exists in the other body tissues. In support of this thesis it is well known that in all mitotic epithelial tissues there is a perfect balance between the production of new cells, whether slow or fast, and the loss of old mature cells; that after wounding the healing response involves the same two processes of cell migration and cell division as in epidermis; and that these processes occur only in the tissue that has been damaged, and not in the adjacent tissues, so that the control mechanism must be tissue specific.