Effect of relaxin on mammary growth in the hypophysectomized rat
Wright, L.C.; Anderson, R.R.
Advances in Experimental Medicine and Biology 143: 341-355
1982
ISSN/ISBN: 0065-2598 PMID: 7064747 Document Number: 182863
11 groups of 3 hypophysectomized female rats were injected daily for 10 days with various combinations of thyrotrophin (0.3 IU), oestradiol benzoate (0.1 mu g), relaxin (40 mu g), prolactin (20 IU), progesterone (0.2 mg) and growth hormone (1.6 IU). On the 11th day, the animals were killed and mammary glands were excised and prepared as whole mounts. Relaxin significantly increased lengthening of the ducts and acted with other mammogenic hormones to promote growth and branching of ducts into end buds. Oestradiol, alone and with progesterone, increased the number of ducts and end buds. Prolactin enhanced widening of ducts and development of end buds. Growth hormone in combination with the other hormones accelerated development of the lobulo-alveolar structures. It is concluded that relaxin is a mammary gland spreading factor, which enables mammogenic hormones to stimulate epithelial cell growth into the space previously occupied by connective tissue cells.