Joseph Marshall Flint 



79 



central portions of the gland although instances are not uncommon 

 where they are found either in the capsule or its neighborhood indicating 

 their points of entrance and exit to and from the substance of the organ. 

 The quantity of the connective tissue diminishes with the order of rami- 

 fication until the small arteries, veins and capillaries are reached. These 

 raturally are found in the finer septa or trabecule about the cell columns. 

 To Ludwig and his pupils we owe the view that many organs are 

 divided into a series of similar structural units which have constant and 

 definite relations to connective tissue processes, blood vessels, nerves and 

 lymphatics. An organ is composed of a great many of such units which 

 are repeated again and again in its formation. Glands like the pancreas, 

 salivary gland, liver, and spleen express their structural relationships 

 excellently while others as for example the stomach and adrenal cannot 



Flo. 2.— Section of block of tissue shown in Fig. 1. about 45 microns ttiick. X 3". Stained 

 with Aniline blue. Drawn over a blue print which was subsequently washed out. The sec- 

 tion shows the capsule of the parathyroid, the larger septa and blood-vessels as well as the 

 smaller septa limiting the cell columns. c=Capsule. s=Finer septa. d=Coarser septa. 

 a= Blood-vessel. 



be subdivided at all. Accordingly when we know the finer structure of 

 one unit we know the structure of the whole organ with the exception of 

 the relation of these units to each other. In this sense, however, there 

 are no structural units in the parathyroid which bear a constant relation- 

 ship to connective tissue processes. The ultimate structural integers 

 must be looked upon as the cell columns or cell groups and the adjacent 

 fibrous tissue which supports them. 



In thin digested sections the framework appears as irregular septa 

 which do not form a continuous network throughout the organ, but are 

 broken up into smaller processes which support the irregular coiled 

 columns of cells of which the organ is composed. These septa carry the 

 arteries, capillaries, veins, and nerves. They are in some places built up 

 of fasciculi of reticulum fibrils, in others, of a thinner, looser formation 



