SOME EFFECTS OF DENERVATING AND TRANSPLANTING MAMMARY GLANDS

¹ A. R. C. Institute of Animal Physiology, Babraham, Cambridge

Techniques are described for transplanting whole mammary glands of goats either in two stages onto the side or in one stage to the neck. In the two-stage technique the major blood vessels were cut as well as the nerves at the first operation.

The milk yield of four glands transplanted in one stage during lactation was 80-118 per cent of the control gland left in the normal site in the 6 weeks after moving. The milk was of normal composition and no significant changes in milk distribution or pressure in the gland before milking was detected after moving. Such glands were capable of normal growth and function during the subsequent pregnancy and lactation.

The milk yield of two glands transplanted to the necks of other animals as homografts was 80 per cent of the previous level in the first 24 hr., but rapidly fell to zero in 8 days on a female and within 2 days on a castrated male. This may be an early sign of the homograft reaction.

Glands transplanted in two or more stages in virgin or non-lactating animals showed no immediate loss of tissue but grew less well than the control glands in the normal site and yielded less milk, particularly when the moving was done before puberty. The lesser amount of mammary tissue formed was of normal histological appearance and secreted normal milk but there was a compensatory hypertrophy of the control gland.

Section of the mammary nerves to one gland had little or no effect on its subsequent growth and function in guinea-pigs.

In Saanen goats bearing only denervated glands (i.e. one or two transplanted) where normal milk ejection was not observed, the total yield of milk was little affected. The normal milk-ejection reflex was only of importance in aiding complete emptying of the glands, when they were very full. This is believed to be due to the large storage capacity of the glands in these animals, and the effectiveness of massage in emptying the glands in some animals.

Saanen goats used in this work with transplanted or sympathectomized glands, or with one gland removed, suffered more reproductive disease (sterility, abortion, mastitis and excessive relaxation of the uterus and pelvic ligaments at parturition) than other similar goats in the same herd at the same time.

Note:

I have been greatly helped by the skilled technical assistance of Mr. I. R. Fleet and Mr. R. D. Burton and by the conscientious care of the animals by Mr. R. R. R. Richbell, Mr. D. C. Hall and Mr. J. W. Cornwell. I am also grateful to my colleagues (particularly Dr. D. C. Hardwick) for many helpful discussions and to Professor P. R. Allison, Miss Pat Bradley and Miss Mary Sheehy and my wife for assistance at some of the operations. The histological sections were prepared by Mr. W. S. Hardy, Mr. F. Baldwin and Mrs. E. Courtenay and the photographs were taken by Mr. A. L. Gallup. Micropaque was kindly given by Damancy & Co. Ware.