Abstract
Greuter 1 has recently reported that the injection of anterior pituitary extracts into lactating cows and goats increases the flow of milk. Corner 2 in a recent demonstration has shown that it is possible to initiate the milk flow in oöphorectomized adult virgin rabbits by injecting an anterior lobe extract.
At the time of these reports the present authors were engaged in a study of the factors concerned in mammary growth and milk secretion. The animals employed were normal and castrated immature male and spayed immature female guinea pigs. The animals were given a preliminary treatment consisting of daily subcutaneous injections of a lipid extract of sows' corpora lutea. This treatment produced a very marked hypertrophy of the glands and nipples as was demonstrated both macroscopically and by histological study. In no instance (12 animals) was milk secreted although in some cases injection was continued for a month. If, however, the growth treatment was followed by injection of anterior pituitary substance, milk was secreted within 3 days (7 animals). Since either fresh gland (rat) or an extract of sheeps' glands containing the maturity hormone∗ proved efficacious in this respect it seems probable that the maturity hormone of the pituitary is the one involved in this reaction. It is possible, of course, that an at present unknown principle of the anterior lobe rather than the maturity hormone is responsible, but the nature of the material used in this work is indicative of the latter.
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