The Action of X-Rays on the Endocrine Glands

Abstract

THE entire field of internal secretion offers, as yet, many questions for investigation, the solutions of which constitute many difficult problems. In experimental research the greatest difficulties arise from the fact that the glands of internal secretion exert an influence upon each other. For this reason, it seems impossible to treat of the function of an individual gland, or to isolate such a function experimentally; the changes that occur after the pathologic disturbance of a gland of internal secretion or after its complete cessation of function, are usually the result of compensatory influences of other glands. It is, therefore, permissible to refer the whole of the secondary phenomena to one gland only under definite conditions. The difficulty of isolating individual functions grows when we recognize that this action on other endocrine organs is not conveyed by way of the blood stream only; we know to-day that such an influence can be exerted also through the vegetative nervous system which regulates the secretion of glands in general. To speak, therefore, as we habitually do of the function of one endocrine gland, is justified only to the extent that we signify by that the predominant function of this gland, a function which cannot be replaced, or that, dependent upon the activity of this gland of internal secretion, certain definite secondary symptoms occur in the rest of the body. It must be added that there is no absolute regularity for this mutual relation between endocrine glands. We know, for instance, that glands of internal secretion respond to definite physiologic and pathologic reactions of the body not only by definite functions but also by changes of their external morphology. Suppression of the ovarian action usually causes hypertrophy of the thyroid; in pregnancy there is also hypertrophy of the thyroid. On the other hand, it can always be found that this reaction will not occur in individuals in whom we have no suspicion whatsoever of an endocrine disturbance. At the same time, hypertrophy can occur in the same patient during one pregnancy, whereas in the next pregnancy the thyroid may remain entirely normal. There are then not only individual variations causing differences between different persons, but it becomes apparent that there are also variations in the reactions which the same person shows at different times. The explanation of these actions and reactions, which seem so variable in different individuals and in the same individual at different times, was extremely difficult as long as the whole problem of internal secretion was regarded only from a purely physiological-chemical point of view. We know today that the vegetative nervous system has an intimate connection with the function of endocrine glands. The tonus of the sympathetic and parasympathetic nervous system is influenced by secretion of these glands, and, inversely, these nervous mechanisms frequently exert an influence on these glands.