Abstract
It has been suggested 1 , 2 that the hypophysis, in addition to its many other functions, may play a part in erythropoiesis.
It has long been known that in man and animal, under the conditions of reduced oxygen tension, there occurs an increase in hemoglobin, erythrocytes and reticulocytes in the blood, and hyperplasia of the bone marrow. It was thought that if the hypophysis furnished a hormone which affected the erythrogenetic tissues, the response to a diminution in oxygen tension in the tissues of hypophysectomized animals might be deficient in one or more respects. To test this hypothesis, 8 male white rats weighing 150 to 220 gm. were hypophysectomized after complete blood counts were done by the usual methods. Erythrocyte counts were done in duplicate; reticulocyte counts of 1,000 cells on a cover slip smear stained with cresyl blue, hemoglobin determinations with the Haden-Hauser hemoglobinometer. Eight days later, 4 of the experimental animals with 4 normal controls of similar weight were placed in the respiratory chamber devised by Dallwig, Kolls and Loevenhart. 3 The remaining 4 animals were placed in the chamber 25 days after hypophysectomy, and a second group of 8 hypophysectomized animals was similarly divided and exposed to the same experimental procedures 9 and 32 days after operation. In all instances complete blood counts were done on the day the animals were placed in the chamber. The pressure was reduced in all experiments to 422 mm. Hg.; equivalent oxygen tension, 12% of an atmosphere, which corresponds to an altitude of approximately 16,000 feet. This level was maintained constantly with but 2 to 3 mm. Hg. variation. Blood counts were made at intervals between 3 and 6 days. Some of the animals died in the first week under the experimental conditions, so that adequate data were obtained on but 14 hypophysectomized and 14 normal animals. The results were remarkably constant and they appear to be significant.
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