. The endocrine organs; an introduction to the study of internal secretion . ood such asbread and milk; the latterwhen the diet has beencomposed of lean feeding of rats o O with lean meat led eventu-allv to a shrinking in size t> O of the vesicles and of thewhole organ, these changesbeing associated with dry-ness of skin, falling off ofhair, and other evidencesof ill-health; in carnivora results of this kind were not observed. Development.—The thy-roid is originally developedlike an ordinary secretinggland by a median outgrowthfrom the entoderm lining thefloor of the pharynx
. The endocrine organs; an introduction to the study of internal secretion . ood such asbread and milk; the latterwhen the diet has beencomposed of lean feeding of rats o O with lean meat led eventu-allv to a shrinking in size t> O of the vesicles and of thewhole organ, these changesbeing associated with dry-ness of skin, falling off ofhair, and other evidencesof ill-health; in carnivora results of this kind were not observed. Development.—The thy-roid is originally developedlike an ordinary secretinggland by a median outgrowthfrom the entoderm lining thefloor of the pharynx at alevel between the first andsecond branchial pouches(fig. 2). It appears very earlyand grows backwards as asolid column of cells, bifur-cating at the upper end ofthe trachea into two lateralportions. The solid columnbecomes hollowed out into aduct (ductus thyreoglossus),which presently becomes obli-terated, usually completely;its original opening is markedthroughout life by the fora-men ccecum at the back of The lateral parts into which the caudal end divides, branch. • FIG. SB.—Section of thyroid of another wild rat. Magnified250 diameters. The vesicles contain little or no colloid ;the epithelial cells are columnar. (Chalmers Watson.) the tongue. 16 The Endocrine Organs again and again to form a system of hollow epithelium-lined tubes, andlater these become cut up into the closed vesicles which are characteristicof the gland. The thyroid bud is joined by outgrowths from the ventral
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Keywords: ., bo, bookcentury1900, bookdecade1910, bookidendocrineorgansi00shar
