THYREOID GLAND OF THE TELEOSTS 



777 



the follicular diameters vary from 50-400^, the median size 

 follicles being the most abundant. 



The follicular epithelium is always cuboidal. Colloid is present 

 in almost all the folHcles, and is very brittle and homogeneous. 

 In the larger follicles the colloid stains much hghter than in the 



.- w 



m0^ 



Fig. 19. Sections through the thyreoid gland of Opsanus. A, anterior to; B, 

 at the aortic bifurcation; C, at the second branchial arteries. 



smaller. Lymphocytes are numerous within the follicles. The 

 blood supply of the thyreoid region is very poor. 



MURAENOIDES GUNELLUS L. 



Length of specimen 1^.0 cm. The thyreoid gland in the butterfish 

 reaches a considerable size (pi. II, fig. 19). The anterior end 

 hes in front of the aortic bifurcation and consists only of small 



