John P. Mixner

Strain Differences in Response of Mice to Mammary Gland Stimulating Hormones.

Summary Four strains of albino were studied as to mammary lobule-alveolar growth responses to anterior pituitary preparations and progesterone. Statistically significant differences in strain responses were found. The Schwing and Swiss strains of mice were definitely superior to the Kansas and Sutter strains in their response to anterior pituitary preparations. The Swiss, Kansas, and Sutter strains of mice were all inferior to the Schwing strain in response to progesterone.

Growth of the Lobule-Alveolar System of the Mammary Gland With Pregneninolone.

Summary Pregneninolone alone and injected subcutaneously with estrone into castrate virgin female mice caused the development of the lobule-alveolar system of their mammary glands, having a property similar to progesterone in this respect. The injection of estrone with the pregneninolone enhanced this activity of the pregneninolone by five times. Pregneninolone has one-half the activity of progesterone in stimulating mammary lobule-alveolar growth when both are injected with estrone.

Influence of Local Applications of Turpentine on Mammary Gland Growth and Involution.

Summary The application of spirits of turpentine for 7 days to the nipples and adjoining skin of lactating mice weaned on the 4th day after parturition was shown to retard the rate of involution of the mammary lobule-alveolar systems. Similar applications of turpentine to castrate and normal females failed to stimulate the growth of alveoli. Pseudo-pregnancy was not stimulated in the normal female. It is suggested that the retardation in the involution process is due to the great subcutaneous hyperemia produced by the turpentine applications.

Qualitative Progesterone Assay of Pregnant Cattle AP and Extracts Having Mammary Growth Activity.

Summary Fresh pregnant cattle pituitary in amounts which will stimulate growth of the lobule-alveolar system in castrate female mice was found to contain insufficient progesterone to give a positive response by the sensitive McGinty technic. Lipid extracts of the AP which stimulate duct growth in the male mouse were also found to be negative for progesterone. These observations are taken to indicate that neither the mammogenic duct nor lobule-alveolar effects of the AP are due to the presence of progesterone.

Influence of Environmental Temperature on Growth of Mammary Lobule-Alveolar System.

Summary Ovariectomized virgin female mice kept at a high environmental temperature (35°C) had a decreased ability to respond to progesterone and estrone injections with mammary lobule-alveolar growth. This same high temperature did not inhibit this response in animals injected with a pituitary extract containing the mammogenic lobule-alveolar growth factor which directly stimulates mammary gland growth. Thus the anterior pituitaries of animals kept at a high environmental temperature have a decreased ability to respond to the stimulus of progesterone plus estrone with the secretion of the mammogenic lobule-alveolar growth factor.