454 THE DUCTLESS GLANDS 



The epithelium rests upon a very delicate reticular basement 

 membrane and is in close relation with the capillaries and lym- 

 phatic vessels of the interfollicular stroma. Colloid material, 

 similar to that within the follicles, has been repeatedly found 

 within the lymphatic vessels (Baber,* Langendorf, f HiirthleJ) 

 and may be readily demonstrated in most sections of the thyroid. 

 Undoubtedly this does not, however, represent the entire " inter- 

 nal secretion " of the gland. 



Blood Supply. The arteries form a rich plexus in and about 

 the capsule of the thyroid, from which numerous branches pene- 

 trate the organ, lying in the connective tissue trabeculae between 

 the lobules ; they are distributed to all parts of the gland. They 

 supply a rich capillary plexus in the walls of the follicles. The 

 veins retrace the course of the arteries. The walls of the smaller 

 venules consist only of endothelium, with a very thin coat of elastic 

 connective tissue. 



Lymphatics. The thyroid is very abundantly supplied with 

 lymphatic vessels. These form a plexus of very broad lacunar 

 capillaries in the interfollicular connective tissue, where they stand 

 in intimate relation with the follicular epithelium. From this 

 plexus vessels pass to the interlobular connective tissue, in which 

 they form a second plexus, whence lymphatic vessels pass out of 

 the thyroid in company with the blood vessels and enter the deep 

 cervical lymphatic nodes. 



Nerves. The nerves of the thyroid are derived from the sym- 

 pathetic and are mostly non-medullated. They accompany the 

 arteries and form a delicate terminal plexus in the walls of the 

 follicles. The finer fibrils of this plexus end in contact with the 

 epithelium. Berkley found occasional fibrils which apparently 

 penetrated between the epithelial cells, but his observations have 

 not yet been corroborated. 



ACCESSOEY OR ABERRANT THYROIDS 



These bodies, first described by Zuckerkandl, || are widely dis- 

 tributed through the connective tissue of the cervical region. 

 They are most frequently found in the course of the embryonic 

 thyreo-glossal duct and in the immediate vicinity of the lateral 

 lobes of the thyroid. They present the appearance of embryonal 



* Phil. Trans., 1876. f Arch. f. Physiol., 1889, Suppl. Bd. 



\ Loc, cit. Johns Hop. Hosp. Rep., 1895. i Stuttgart, 1879. 



