558 



THE DUCTLESS GLANDS ENDOCRIN GLANDS 



and especially in specimens which have been fixed and hardened in alco- 

 hol, it presents a vacuolated appearance. As a rule the lumen of the 

 follicle is not completely filled with the colloid mass, which is then 

 adherent to the surface of the lining epithelium by delicate thread-like 



FIG. 483. FROM A SECTION OF THE HUMAN THYROID GLAND. 



a, thyroid follicles in transection; b, tangential section of the follicular wall. 

 Hematein and eosin. Photo. X 110. 



processes; the colloid thus acquires a deceptive appearance of extreme 

 contraction, as if its surface, except for occasional delicate strands, had 

 been drawn away from the epithelium. 



Occasionally a single large vacuole, often containing basophil gran- 

 ules or crystalloid particles, occupies the center of the colloid mass in 

 the larger follicles; at other times the colloid material appears to be 



