An introduction to the study of the endocrine glands and internal secretions : Lane medical lectures, 1913 / by Sir Edward Schäfer.

  • Sharpey-Schäfer, E. A. (Edward Albert), Sir, 1850-1935.
Date:
1914
Catalogue details

Licence: Public Domain Mark

Credit: An introduction to the study of the endocrine glands and internal secretions : Lane medical lectures, 1913 / by Sir Edward Schäfer. Source: Wellcome Collection.

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    plest manner in which one can conceive this to occur is by contraction of (plain) muscular tissue around the alevoli. In support of this opinion I have lately succeeded in observing in the well of the mammary alveolus in the cat long rod shaped nuclei immediately external to the epithelium. These nuclei exactly resemble those of involuntary muscle-cells and I have no doubt that they belong to a thin muscular layer which, like the muscu¬ lar tissue of the sweat-glands, is probably situated between the basement membrane and the epithelium of the alveoli. The action of pituitary extract upon milk secretion differs from its effect upon the secretion of urine in the fact that in the last named case there is an actual stimulation of the renal cells to abstract fluid from the blood, and not a mere contraction of alveoli and outpouring of previously secreted fluid. Apart from the pouring out of the contents of the alveoli—or rather the tendency of the alveoli to empty themselves towards the nipple— which is excited by the pituitary galactagogue, there is but little tendency to cause an increased production of milk. This at least is the result which was obtained in cows by Gavin. Later observers (Hammond and Suther¬ land Simpson) have obtained a slight increase in the diurnal yield of both goats and cows and also a slightly increased amount of fat in the milk produced under the influence of the autacoid. Mackenzie found that in the cat atropine does not arrest the flow of milk obtained as the result of pituitary injection (an observation which has been confirmed for the cow by Houssay). He obtained, however, an inhibitory action from extracts of placenta, which, when injected into a vein just previously to the injection of pituitary extract, prevented the effect of the latter from influencing the mammary gland. It is reason¬ able to conclude from this that placenta extract must contain a chalonic autacoid which restrains the outpouring of the secretion of the mamma and antagonizes the harmonic action of the pituitary autacoid. The mamma is much more sensitive to the action of pituitary extract than are other organs (except perhaps the uterus) and an outflow of milk can be obtained with a dose which produces no appreciable effect on the blood-pressure or kidney. This is well illustrated by an experiment by Herring with the skate’s pituitary. In this no effect was shown on the blood-pressure or kidney, but there was abundant outflow of milk. Or it may be that the effect is due to a special hormone and that the one which influences blood-pressure and kidney secretion is absent in the skate’s pituitary. The blood of non-laetating animals sometimes con¬ tains enough of the galactagogue autacoid to provoke the mammary secre¬ tion of a lactating animal, although the other effects of pituitary autacoid