Studies on the Hormonal Induction of Mammary Growth and Lactation in the Goat

Abstract

Extensive morphological and functional investigations have been carried out on the artificial induction of mammary development and lactation in the goat using hexoestrol alone and in combination with progesterone, at several dose levels and proportions. Administration of the oestrogen and progesterone was either by tablet implantation or by subcutaneous injection in oily solution. Forty animals were used, of which twenty-three were ovariectomized during infancy. Special histological techniques were devised for studying and estimating quantitatively the degree of mammary development. In the later experiments this was achieved by surgically removing one half of the udder, i.e. one gland, when the lactation curve had reached a maximum. In three normally lactating goats the operation had no influence on the milk yield of the remaining gland.For the dose levels used, the milk yields of the animals receiving oestrogen and those receiving oestrogen and progesterone did not differ significantly. In general, the artificially induced milk yields were below the expected yields had the animals come into lactation after kidding.It appeared highly probable that the total area of secretory epithelium in the artificially developed gland was less than in the normally developed udder. A high correlation was observed between the surface area of the secretory epithelium in the entire half udder and the milk yield.Several marked abnormalities were observed in the microscopic structure of the udders. These were less evident in the glands of the goats receiving progesterone provided the oestrogen dose was not excessive.Since the original demonstration by Folley, Scott Watson & Bottomley [1940, 1941] that udder growth and copious lactation could be elicited in the virgin goat by treat¬ ment with synthetic oestrogens without supplementary treatment with anteriorpituitary lactogenic hormones, numerous spectacular applications of this procedure to farm animals (mainly bovines) have been described. These studies up to 1947 have been reviewed by Malpress [1947]. Since that time further studies have been made on the bovine [

Some Effects of Denervating and Transplanting Mammary Glands

“…In histological studies of the hormonal control of mammary growth in goats, Cowie, Folley, Malpress and Richardson [1952], Benson, Cowie, Cox, Flux and Folley [1955] and others since, have removed one gland early in lactation for histological study and compared this with the subsequent milk yield of the remaining gland. This seemed justified because they reported that unilateral mastectomy in three Saanen goats at the peak of lactation had no noticeable effect on the subsequent yield of the other gland.…”

“…However apart from the study of Cowie et al [1952], this phenomenon has not been investigated. It must be admitted that variations in the rate of milk secretiorn from week to week, month to month and lactation to lactation make it difficult to predict milk yields, nevertheless the measured increases in volume of tissue and milk yield recorded in this work after removal of one gland seem unlikely to have occurred by chance in every case.…”

Antiestrogen Action of Progesterone in Breast Tissue

“…These changes ob served with supraphysiologic doses of estro gen seem to be comparable to human fibro cystic disease [7,8], In contrast, when estra diol is administered in combination with progesterone, complete and proper develop ment of the mammary gland is observed when the ratio between estrogen and proges terone is adequate [10,11]. Cowie et al [9] found that a combination of estrogen and progesterone in castrated goats resulted in uniform development and secretion when the dose of estrogen remained low (0.25 mg/day). An increase in the estrogen dose to 1.0 mg/day resulted in cysts and epithelial proliferation.…”

Luteal phase defect and breast cancer genesis

“…Under estrogen stimulation, it secretes a watery muco'id substance that has a tendency towards hyalinization (8,9). Progesterone, at least experimentally, appears to have the opposite effect (10,11). In addition, during culture of human ducts, fibroblasts develop extensively, and preliminary results (Kuttenn, in preparation) indicate that they contain very extensive enzymatic activity leading to the catabolism of both estradiol and progesterone (12).…”