. The endocrine organs; an introduction to the study of internal secretion . s a provenfact. It has been stated that the iodine content of a thyroid lobe isdiminished as the result of excitation of the vagus of the same side, butthis also needs confirmation. The view which was at one time held that the function of the thyroidis merely that of a destroyer of toxic substances circulating in the blood isno longer tenable. The same may be said for an old idea—resuscitated byCyon—that the organ serves as a kind of shunt to regulate the flow of bloodin the cranial cavity. This, indeed, has nothing t
. The endocrine organs; an introduction to the study of internal secretion . s a provenfact. It has been stated that the iodine content of a thyroid lobe isdiminished as the result of excitation of the vagus of the same side, butthis also needs confirmation. The view which was at one time held that the function of the thyroidis merely that of a destroyer of toxic substances circulating in the blood isno longer tenable. The same may be said for an old idea—resuscitated byCyon—that the organ serves as a kind of shunt to regulate the flow of bloodin the cranial cavity. This, indeed, has nothing to support it beyond theextreme vascularity of the gland and its position in close connexion withthe carotids. CHAPTER VIITHE THYMUS GLAND THE STRUCTURE AND DEVELOPMENT OF THE THYMUS RELATIVELY to the rest of the body the thymus is largest at birth, but itremains well developed during childhood. It is essentially an organ ofearly life. After puberty it generally undergoes retrograde changes; theseconsist in diminution in volume of the proper gland substance accompanied. FIG. 28.—Part of lobule of the thymus of a child. Magnified 60 , cortex ; m., medulla ; 6., b., large blood-vessels in connective tissue trabeculee. by an increase in connective tissue, the whole organ becoming smaller andoften embedded in a mass of fat. Occasionally it remains fully developed ;such cases are generally associated with an unusual development of lym-phatic tissue in the body, the condition being termed status lymphaticus. In its developed condition the thymus consists of two main lobes, oneon each side, the lobes themselves being subdivided into lobules and thewhole strung together in an irregular manner along a strand of connectivetissue which sends offsets into the lobes, subdividing the lobules from oneanother and sending partial septa into the individual lobules. The con- 45 46 The Endocrine Organs nective tissue conveys blood-vessels, lymphatics, and nerves to and fromthe org
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