[Changes in the hematopoietic system and mucosa of the small intestine in the breathing of pure oxygen under normal atmospheric pressure].

Normobaric hyperoxia upon breathing pure oxygen for 20 and 120 min is capable to produce in (CBA X S57B1)F1 mice a short-term (up to 1 day) cytostatic action on bone marrow tissues. Under the same conditions oxygen reduced proliferative activity in duodenal crypts by the 3rd and 6th days of the experiment. Changes in the morphological composition of the blood manifesting in the increased counts of leukocytes, neutrophiles, eosinophiles and monocytes are physiological and compensatory in nature.