[The characteristics of the effect of space flight factors on regeneration processes in mammals and Urodela].

Comparative analysis of experimental studies on regeneration of bone and muscle tissue under the influence of space flight factors (SFF) during restoration of experimental fracture in rats and epimorphic limb regeneration in adult newt is presented SFF-induced retardation of regeneration in mammals and its acceleration in tailed amphibians results from changed calcium metabolism in conditions of microgravity. Bidirectional effect of SFF on bone regeneration is due to specific control of calcium homeostasis in these taxa. Upon termination of the space flight (SF) the Wistar SPF rats proved to have increased functional activity of parathyrocytes and blocked calcitonin secretion to the blood by the C-cells of thyroid gland. Hence, inhibition of posttraumatic bone regeneration in rats is due to decreased formation rate and enhanced resorption of bony tissue. Sharp decrease of the calcitonincytes population following the initial hypertrophy of ultimobranchial gland (UBG) is observed in adult newt Pleurodeles waltlii Michah during SF. Progressing demineralization of skeletal elements including the amputated limb stump accelerates the first stages of its regeneration in conditions of SF.