THE PATHOLOGICAL ANATOMY 



275 



Primary Hyperplasias Developmental stage. Tracing the develop- 

 ment of hypertrophy and hyperplasia from the normal gland, the first 

 change noticed in the thyroid is a 



store, 

 This 



Fig. 9. Active hyperplasia thyroid of 

 bony fish (Salvelinus fontinalis) illustrat- 

 ing the vascularity and alveolar distor- 

 tions. (After Marine and Lenhart, J. 

 Exper. Med., 1911: 13.) 



marked drop in the iodin 

 usually below 0.1 per cent, 

 is associated with a decrease in the 

 stainable colloid. The blood sup- 

 ply to the gland is increased, the 

 capsule vessels dilate, hypertrophy 

 and become tortuous. The capil- 

 lary network about the alveoli also 

 shares in the dilatation and hyper- 

 trophy. The gland becomes larger, 

 softer and takes on a brighter red 

 color. Microscopically, there is a 

 lessening of the stainable colloid 

 which at first manifests itself by a 

 paler stain, later by vacuolization, 

 and finally by the actual disappear- 

 ance of the true colloid its place 

 being taken by a thin albuminous 

 fluid, which when coagulated has the appearance of granular albumi- 

 nous debris. As this colloid gradually disappears from the alveolus, the 



epithelial cells change from the low 

 cuboidal to columnar and, finally, to 

 high columnar. With the disappear- 

 ance of the colloid and with the growth 

 in size and number of epithelial cells, 

 the color of the gland changes from the 

 normal translucent amber-red to reddish 

 transmcency, to grayish-red and finally 

 to the soft fleshy gray-red and opaque 

 color of the marked hyperplasia. As 

 the hyperplasia of the epithelial cells 

 take place, the alveoli at first enlarge, 

 later (to some extent due to the restrain- 

 ing influence of the capsule), infoldings 

 and plications of the lining epithelium 

 begin to appear. These infoldings may 

 become so extensive as to fill the space 

 formerly occupied by the colloid. The 



gland capsule and stroma also show hyperplasia roughly parallel with the 

 epithelial proliferation and increased blood supply. In the active stages of 

 hyperplasia the stroma increase is not prominent, while in the late or 



\ 



Fig. 10. Active hyperplasia, 

 marked degree, in thyroid of bony 

 fish (Salvelinus fontinalis) giving 

 papillary effect. (After Marine and 

 Lenhart, J. Exper. Med., 1911: 13.) 



