l66 NORMAL HISTOLOGY. 



TECHNIQUE. 



Sections. A human supra-renal capsule, as fresh as 

 possible or, if this cannot be obtained, that of the 

 guinea-pig or ox, is cut transversely into two or three 

 pieces and hardened in Muller's fluid. Transverse sec- 

 tions are stained double and mounted in glycerin or 

 balsam. 



THE THYROID GLAND. 



The thyroid gland is composed of a congeries of 

 larger and smaller spheroidal or irregular-shaped 

 alveoli, inclosed in connective tissue and grouped 

 together to form lobules. The alveoli are entirely 

 separate from one another, and they have no excre- 

 tory ducts. Each alveolus has a delicate membrana 

 propria, and is lined with a single layer of cylin- 

 drical or cuboidal cells. The connective tissue 

 between the alveoli contains numerous blood- and 

 lymphatic-vessels. 



The entire gland, which consists of two lateral 

 lobes, united at their lower extremities by a trans- 

 verse commissure, is enclosed in a dense connective- 

 tissue envelope. The alveoli are filled with a clear, 

 homogeneous albuminous fluid, which in adult life 

 is frequently transformed into or replaced by a 

 translucent material, called colloid. Owing to the 

 pressure which the accumulating colloid substance 

 exerts on the epithelium lining the alveoli, they are 

 often very much flattened, and not infrequently 

 almost entirely disappear. * The colloid material 



