Morphological manifestations of functional changes in the hypothalamic-pituitary neurosecretory system and kidneys of rats after space flight.

Morphological examination of the hypothalamic-pituitary neurosecretory systen and kidneys of rats flown for 22 d and sacrificed 2 and 27 d postflight was carried out. By histological and histochemical methods, indications of increased activities of the hypothalamicpituitary neurosecretory system and the juxtaglomerular apparatus of kidneys were found. The changes were reversible and by the 27th postflight day returned to the normal. It is suggested that the changes in the above systems may be produced not only by flight effects but also by readaptation of animals to 1 g.