Cell-mediated and neural control of morphostasis.
Morphostasis refers to the maintenance of the differentiated state of tissues in an adult individual and it represents a basal event of homeostasis and the organism's existence. Most of the cells in the body are arrested in their differentiation at a certain point related to their optimal function. Evidence is rapidly accumulating on the general role of immunoglobulin-gene superfamily (IGSF) domains in the non-immune control of behavior of cells in various tissues. A novel 'tissue control system' (TCS) has been suggested, supporting the differentiation of tissue cells in an adult organism and functioning via the IGSF domains and cell-mediated control of morphostasis. We assume here that the morphostasis is established epigenetically during the early adaptive period. With its termination, coinciding with the attainment of an organism's immunocompetence, the combination of cell surface markers of the most mature cells in tissues are encoded in the TCS as the stop-signal (SS). This stage of tissue differentiation is maintained during further life: upon recognition of SS the committed TCS element does not stimulate further differentiation of the cell, i.e. it exhibits a stop-effect (SE). Each tissue-specific cell line has only one or no SE established depending on its presence or absence during development, respectively. The only way to escape an established SE and continue in differentiation is to change at least a portion of the SS. Hormones might act here directly, by conformation of their cell surface receptors recognized as a portion of SS, or indirectly, by influencing proteosynthesis of cell surface markers.(ABSTRACT TRUNCATED AT 250 WORDS)