STUDIES ON THE PHYSIOLOGY OF REPRODUCTION IN BIRDS

Abstract

Tests were made of the effects of various pituitary hormones on weights of gonads and several other organs in 57 birds; 39 blank-injected birds were used as controls. The immature testis of the dove and pigeon provides an extraordinarily sensitive test for the sex maturity hormone; 10 daily doses yield weight increases of 500-2,200%; 3 daily doses give increases of more than 100%. The growth response of the ovary of the immature dove and pigeon is not more than 1/3 or 1/4 that observed in the testis. Alkaline extracts of the anterior pituitary rich in the maturity principle, and probably containing the growth hormone, produced prompt and marked increase of weight in thyroid and liver; most other organs showed little or no change in size. Antuitrin stimulates growth in immature testes; but in similar dosage and short-term tests it gives no measurable response in the ovaries. None of these results is ascribable to contamination of the extracts by posterior lobe principles; under the conditions observed in these tests pitocin and pitressin do not affect the size of gonads, thyroids, or liver. The luteinizing hormone from pregnant urine has no effect on size of liver or thyroid, but it decreases the size of the oviduct (uterus) and stops or retards growth in the ovary. Its action is distinct from, perhaps antagonistic to, that of the maturity principle.