Production of Polycythemia in Hypophysectomized Rats by the Pituitary Erythropoietic Factor1

EVIDENCE has recently been presented that the pituitary contains an erythropoietic factor which, administered to hypophysectomized rats, repairs the post-hypophysectomy anemia (Contopoulos, A. N., D. C. Van Dyke, M. E. Simpson, J. F. Garcia, R. L. Huff, B. S. Williams and H. M. Evans, 1953; Contopoulos, A. N., D. C. Van Dyke, S. Ellis, M. E. Simpson, J. H. Lawrence, and H. M. Evans, 1954; Contopoulos, A. N., M. E. Simpson, D. C. Van Dyke, S. Ellis, J. H. Lawrence and H. M. Evans, 1954; Simpson, M. E., D. C. Van Dyke and B. S. Williams, 1954; Van Dyke, D. C, A. N. Contopoulos, B. S. Williams, M. E. Simpson, J. H. Lawrence and H. M. Evans, 1954). This pituitary erythropoietic factor does not appear to act through any of the known pituitary target organs. None of the known pituitaiy hormones or the hormones of its target organs have been shown to cause polycythemia when injected into hypophysectomized rats