. The thyroid gland in health and disease. s of itslymph trunks are appearances will vary with the duration of the hyper-plastic stage, and the length of time since reversion to the colloidstage has taken place (fig. 18). Thus the gland may appearmore colloid in type and less hyperplastic or vice versa, accordingto the stage of the process at which it is observed. This ])rocess of reversion to the colloid state, first accuratelydescribed by Marine and Lenhart, represents the second stage in ENDEMIC GOITRE 69 the production of simple as opposed to exophthalmic onset i
. The thyroid gland in health and disease. s of itslymph trunks are appearances will vary with the duration of the hyper-plastic stage, and the length of time since reversion to the colloidstage has taken place (fig. 18). Thus the gland may appearmore colloid in type and less hyperplastic or vice versa, accordingto the stage of the process at which it is observed. This ])rocess of reversion to the colloid state, first accuratelydescribed by Marine and Lenhart, represents the second stage in ENDEMIC GOITRE 69 the production of simple as opposed to exophthalmic onset in the case of endemic goitre is determined by the factthat goitrigenous influences are intermittent in their action and,as a rule, are only operative during the spring months in endemicareas. If, now, a further attack of hyperplasia occurs in such a colloidgland, the whole process is repeated and the scars become morepronounced. In the case of endemic goitre repeated periods ofhyperplasia succeed one another during succeeding springs, the. ^<*«f Fig. 18.—Section of colloid goitre from human siibject. Note, great irregularityin shape and size of vesicles, their distension with colloid ; the evidences of hyper-plasia in the form of buds, sprigsand cellular areas ; increase of fibrous stroma. X 50. gland reverting in the intervals to the colloid state. So also inpregnancy successive attacks of hyperplasias may occur withsuccessive pregnancies, periods of rest alternating with periodsof activity. A stage is ultimately reached when the secretionfinds its way less readily into the lymph channels. The colloidbecomes more and more viscid, owing possibly to specific chemicalchanges, and is dammed up in the vesicles by the increasingstroma. 70 PATHOLOGY There may also develop in the gland rounded or circumscribedmasses apart from the main body of the goitre (figs. 19, 20).
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