THE EFFECT OF PREGNANCY ON THE ANTERIOR HYPOPHYSIS OF THE RAT AND COW AS JUDGED BY THE CAPACITY OF IMPLANTS TO PRODUCE PRECOCIOUS MATURITY

Abstract

A minimal amount, ap-proximately 35 mgm. of non-pregnant cow hypophyseal tissue, implanted into 24-day old [female] rats, sacrificed on the 4th day, produced the oestrous smear, and development of the ovaries. Hypophyseal tissue from pregnant cows gave similar results, the ovaries being slightly heavier. Hypophyses from pregnant rats were more effective in producing precocious maturity in immature females than the same amount of hypophyseal tissue implanted from non-pregnant donors. Similarity hypophyseal implants from non-pregnant multiparous donors were more potent than from non-pregnant nullip-arous donors.